Olkiluoto Biosphere Description 2006 (pdf) (4.1 MB) - Posiva

POSIVA 2007-02Olkiluoto Biosphere Description 2006Reija Haapanen,Lasse Aro, Hannu Ilvesniemi,Timo Kareinen, Teija Kirkkala,Anne-Maj Lahdenperä,Sakari Mykrä, Hanna Turkki,Ari T.K. IkonenFebruary 2007POSIVA OYFIN-27160 OLKILUOTO, FINLANDPhone (02) 8372 31 (nat.), (+358-2-) 8372 31 (int.)Fax (02) 8372 3709 (nat.), (+358-2-) 8372 3709 (int.)

POSIVA 2007-02Olkiluoto Biosphere Description 2006Reija HaapanenHaapanen Forest ConsultingLasse Aro, Hannu Ilvesniemi, Timo KareinenFinnish Forest Research InstituteTeija Kirkkala, Sakari Mykrä, Hanna TurkkiLounais-Suomenvesi- ja ympäristötutkimus OyAnne-Maj LahdenperäPöyry Environment OyAri T.K. IkonenPosiva OyFebruary 2007Base maps: © National Land Survey, permission 41/MYY/07POSIVA OYFI-27160 OLKILUOTO, FINLANDPhone (02) 8372 31 (nat.), (+358-2-) 8372 31 (int.)Fax (02) 8372 3709 (nat.), (+358-2-) 8372 3709 (int.)

ISBN 978-951-652-150-6ISSN 1239-3096

Posiva-raportti – Posiva ReportPosiva OyFI-27160 OLKILUOTO, FINLANDPuh. 02-8372 (31) – Int. Tel. +358 2 8372 (31)Raportin tunnus – Report codePOSIVA 2007-02Julkaisuaika – DateFebruary 2007Tekijä(t) – Author(s)Reija Haapanen, Haapanen Forest ConsultingLasse Aro, Hannu Ilvesniemi, Timo Kareinen,Finnish Forest Research InstituteTeija Kirkkala, Sakari Mykrä, Hanna Turkki,Lounais-Suomen vesi- ja ympäristötutkimus OyAnne-Maj Lahdenperä, Pöyry Environment OyAri T.K. Ikonen, Posiva OyNimeke – TitleOLKILUOTO BIOSPHERE DESCRIPTION 2006Toimeksiantaja(t) – Commissioned byPosiva OyTiivistelmä – AbstractThis report summarises the current knowledge of the biosphere of Olkiluoto, and it is the firstBiosphere Description Report. The elements considered were climate, topography, land use,overburden, terrestrial vegetation and fauna and sea flora, fauna and water. The principal aim wasto present a synthesis of the present state (now to 2020) and the main features of past evolution ofthe biosphere at the site using currently available data. The lack of site specific parameters andtheir importance was discussed.Conceptual ecosystem models are presented for land and sea. Currently available data made itpossible to calculate the biomass of the terrestrial vegetation and further convert it to carbon. Inthe case of terrestrial animals, preliminary figures are given for moose alone due to lack of sitespecificdata. For the same reason, the sea ecosystem model was not quantified within this work.The ecosystems on Olkiluoto do not deviate from the surrounding areas. Since mires are few onOlkiluoto, forests are the most important land ecosystem. However, coastal areas are the transitionzones between land and sea, and also potential sites for deep groundwater discharge. The majorinterest concerning aquatic ecosystems was laid on four future lakes potentially developing fromthe sea due to the land up-lift. Current sea sediments near Olkiluoto are future land areas, and thusvery important.Spatially, the forest ecosystems of Olkiluoto are now most comprehensively covered, while thetemporal coverage is highest in sea ecosystems. Lack of data is greatest in terrestrial fauna and seasediments. During this work, the system boundaries were crossed and the use of data overdisciplines was started. The data were mostly in agreement, but some discrepancies were detected.To solve these, and to supplement the existing data, some recommendations were given.Avainsanat - KeywordsCarbon, climate, ecosystem, fauna, flora, land-use, overburden, seaISBNISBN 978-951-652-150-6ISSNISSN 1239-3096Sivumäärä – Number of pages175Kieli – LanguageEnglish

Posiva-raportti – Posiva ReportPosiva OyFI-27160 OLKILUOTO, FINLANDPuh. 02-8372 (31) – Int. Tel. +358 2 8372 (31)Raportin tunnus – Report codePOSIVA 2007-02Julkaisuaika – DateHelmikuu 2007Tekijä(t) – Author(s)Reija Haapanen, Haapanen Forest ConsultingLasse Aro, Hannu Ilvesniemi, Timo Kareinen,MetsäntutkimuslaitosTeija Kirkkala, Sakari Mykrä, Hanna Turkki,Lounais-Suomen vesi- ja ympäristötutkimus OyAnne-Maj Lahdenperä, Pöyry Environment OyAri T.K. Ikonen, Posiva OyNimeke – TitleOLKILUODON BIOSFÄÄRIN KUVAUS 2006Toimeksiantaja(t) – Commissioned byPosiva OyTiivistelmä – AbstractTämä raportti kokoaa nykyisen tiedon Olkiluodon biosfääristä ja se on ensimmäinen pelkästäänbiosfääriin keskittyvä kuvaus. Raportissa tarkastellaan ilmastoa, maanpinnan muotoja, maankäyttöä,maaperää, maakasvillisuutta ja -eläimistöä, sekä merta, merenpohjaa ja merieliöitä.Saatavilla olevien aineistojen avulla muodostettiin synteesi biosfäärin nykytilasta (nyt - 2020),sekä esitettiin aiemman kehityksen merkittävimmät piirteet. Samalla pohdittiin mitä Olkiluotokohtaisiatietoja puuttuu ja mikä on näiden merkitys.Raportissa esitetään käsitteelliset ekosysteemimallit maalle ja merelle. Tässä versiossa voitiinestimoida maakasvillisuuden biomassa ja muuntaa se hiileksi. Maaeläinten laskelmat tehtiin vainhirvelle, tarkan Olkiluotokohtaisen tiedon puuttuessa. Meren eri osien biomassoja ja hiilimääriäei estimoitu tässä työssä samasta syystä.Olkiluodon ekosysteemit eivät eroa lähialueista. Soita on vähän, joten metsät ovat merkittävinmaaekosysteemi. Rantakaistaleet ovat kuitenkin tärkeä vaihtumisvyöhyke maan ja meren välillä,ja ne ovat myös mahdollisia syvän pohjaveden purkautumisalueita. Meriekosysteemien esittelyssätehtiin jako alueisiin, jotka todennäköisesti tulevat kehittymään järvialtaiksi maankohoamisenseurauksena. Maankohoamisen vuoksi Olkiluodon lähiympäristön merenpohjansedimentit ovat tulevaisuuden maaperää, ja siten hyvin tärkeitä.Olkiluodon metsäekosysteemien mittaukset ovat tällä hetkellä spatiaalisesti kattavimmat, kuntaas merestä on pisimmät aikasarjat. Suurimmat aineistopuutteet ovat maaeläimissä ja merenpohjansedimenteissä. Tämän työn aikana aloitettiin mittaustulosten analysointi yli systeemirajojen.Tulokset olivat suurimmaksi osaksi yhteneviä, mutta joitain epäjatkuvuuskohtia havaittiin.Näiden selvittämiseksi, sekä olemassa olevien aineistojen täydentämiseksi esitettiin suosituksia.Avainsanat - KeywordsEkosysteemi, eläimet, hiili, kasvillisuus, maankäyttö, maaperä, meri, ilmastoISBNISBN 978-951-652-150-6Sivumäärä – Number of pages175ISSNKieli – LanguageISSN 1239-3096Englanti

1TABLE OF CONTENTSABSTRACTTIIVISTELMÄPREFACE....................................................................................................................... 31 INTRODUCTION ..................................................................................................... 51.1 Olkiluoto Site..................................................................................................... 51.2 This Report ....................................................................................................... 91.3 Delineation of the Study Site .......................................................................... 112 LAND USE ON OLKILUOTO ISLAND................................................................... 133 APPLIED AND AVAILABLE DATA ........................................................................ 194 CLIMATE, METEOROLOGY, AND CHEMICAL DEPOSITION............................. 254.1 Current Climate and Meteorology................................................................... 254.2 Deposition....................................................................................................... 284.3 Past Climate and Vegetation .......................................................................... 305 TOPOGRAPHY, BATHYMETRY, AND SHORELINE DISPLACEMENT............... 355.1 Current Topography........................................................................................ 355.2 Current Bathymetry......................................................................................... 355.3 Land Uplift and Shoreline Displacement......................................................... 405.4 Past Topographical Development at Olkiluoto................................................ 426 OVERBURDEN ..................................................................................................... 456.1 General ........................................................................................................... 456.2 Podzolisation .................................................................................................. 456.3 Physical Properties of Soils on Olkiluoto ........................................................ 466.4 Geochemistry of Soils on Olkiluoto................................................................. 506.5 Mineralogy ...................................................................................................... 536.6 Hydrogeochemistry of Overburden................................................................. 536.7 Radionuclides in Soil ...................................................................................... 596.8 Wetlands......................................................................................................... 607 SEA SEDIMENTS.................................................................................................. 658 TERRESTRIAL ECOSYSTEMS ............................................................................ 698.1 Terrestrial Vegetation ...................................................................................... 698.1.1 Habitats and Species............................................................................. 698.1.2 Biodiversity ............................................................................................ 768.1.3 Nutrient Concentrations ......................................................................... 778.1.4 Radionuclides ........................................................................................ 808.1.5 Estimates for the Larger Area................................................................ 808.2 Terrestrial Wildlife ............................................................................................ 838.2.1 Wildlife on Olkiluoto Island..................................................................... 838.2.2 Power Production Infrastructure and Terrestrial Wildlife ....................... 849 SEA ECOSYSTEMS.............................................................................................. 899.1 Physico-Chemical Water Quality ..................................................................... 899.2 Phytoplankton Production.............................................................................. 105

29.3 Primary Production ........................................................................................ 1109.4 Flora............................................................................................................... 1129.5 Bottom Fauna ................................................................................................ 1139.6 Fish Stocks .................................................................................................... 1159.7 Load Coming into the Olkiluoto Sea Area...................................................... 11710 ECOSYSTEM MODELS FOR LAND AND SEA .................................................. 12110.1 Ecosystem Models and Carbon Cycle......................................................... 12110.2 Terrestrial Vegetation .................................................................................. 12210.3 Terrestrial Fauna ......................................................................................... 12810.4 Sea Ecosystems .......................................................................................... 12911 IDENTIFICATION OF RELEVANT LIMNIC ECOSYSTEMS ............................... 13112 CONFIDENCE AND CONSISTENCY ASSESSMENT ........................................ 13312.1 Are All Data Considered and Understood?.................................................. 13312.2 Uncertainties and Potential for Alternative Interpretation ............................ 13512.3 Consistency Between Different Disciplines ................................................. 14212.4 Overall Judgement....................................................................................... 14313 CONCLUDING REMARKS.................................................................................. 147REFERENCES ........................................................................................................... 153APPENDIX A: MEASUREMENT LOCATIONS........................................................... 171

3PREFACEThe Olkiluoto Biosphere Description report has been written by experts from differentorganisations commissioned by Posiva Oy. On behalf of Posiva, the study has been supervisedby Ari T.K. Ikonen. Reija Haapanen from the Haapanen Forest Consulting hascoordinated the work and edited the report. The main responsibilities of the differentchapters were by the following experts: Climate, meteorology and deposition by Ari Ikonen (Posiva Oy) Overburden and sea bottom sediments by Anne-Maj Lahdenperä (Pöyry EnvironmentOy) Terrestrial vegetation by Lasse Aro, Timo Kareinen, and Hannu Ilvesniemi(Finnish Forest Research Institute) and Reija Haapanen (Haapanen Forest Consulting). Birds and terrestrial fauna by Sakari Mykrä (freelancer/Lounais-Suomen vesi- jaympäristötutkimus Oy) Sea ecosystems by Teija Kirkkala and Hanna Turkki (Lounais-Suomen vesi- jaympäristötutkimus Oy) Topography and land up-lift by Ari Ikonen, Anne-Maj Lahdenperä, and ReijaHaapanen Land use by Ari Ikonen, Reija Haapanen, and Sakari MykräSeveral other experts have reviewed and provided useful comments for the report. Thepresentation of the Biosphere Description Report was given on November 20, 2006, atOlkiluoto for the staff of Posiva and main consultants for the Safety Case and the SiteModelling. Valuable ideas, and comments were received during the discussion. Thefinal draft of the report was reviewed by Ian Crossland (Crossland Consulting). Theauthors wish to thank all who have contributed to reviewing and commenting on thereport.

51 INTRODUCTION1.1 Olkiluoto SiteSpent fuel from the Finnish nuclear power reactors is planned to be disposed of in arepository located on Olkiluoto Island, which is situated on the Finnish coast of theBothnian Sea (Fig. 1-1). The coast is characterised by shallow bays surrounded by smallarchipelagos. The soil of this relatively flat island is mainly fine-texture till originatingfrom the bedrock consisting of mostly mica gneiss and other Svecofennian metasedimentsand plutonic rocks. The landscape in Olkiluoto is characterised by commercialforests, rocky hills, and some nutrient-rich mires and near shore also by meadows andcolonies of common reed. The whole local hydrogeochemical and biological system isaffected by the postglacial land up-lift (approximately 6 mm/y) typical to the Finnishcoast in general.To address the long term safety requirements, Posiva Oy is compiling a Safety CasePortfolio, which was introduced in the Safety Case Plan of 2004 (Vieno & Ikonen2005).Safety CaseIn the following, the main ideas of the Safety Case are summarised, but for a comprehensivepicture of the whole Posiva Safety Case, the reader is advised to see the SafetyCase Plan (Vieno & Ikonen 2005).Figure 1-1. Olkiluoto Island.

6Principles of Safety CaseFirst, the purpose and context of the Safety Case should be made clear and the overallsafety strategy presented. This includes strategies for the siting, design and implementationof the repository as well as the strategy for performing safety assessments (Vieno &Ikonen 2005). Next, the information and analysis tools for safety assessment must bedescribed. These are collectively termed the "assessment basis", and include:The system concept, which is a description of the repository design including theengineered barriers, geologic setting and its stability, how both engineered andnatural barriers are expected to evolve over time, and how they are expected toprovide safety.The scientific and technical information and understanding, including the detailedsupport for the expected evolution and safety of the disposal system andassessments of the uncertainties in scientific understanding.The analysis methods, computer codes and databases that are used in themodelling of the disposal system.The adequacy and reliability of the assessment basis for carrying out safety assessmentsmust also be addressed as a part of the safety case (Vieno & Ikonen 2005, Ikonen 2006).Lastly, a synthesis will be made that draws together key findings from the safety case,namely the principal evidence, analyses and arguments that quantify and substantiatea claim that the repository is safe, including an evaluation of uncertainty. This judgementis a statement of expert confidence in the safety of the disposal system recognisingthat this is expected to increase over the time of the repository development programmein the context of the assessment basis available at the current stage of the repositoryprogramme (Vieno & Ikonen 2005).Posiva Safety Case PortfolioTo benefit from the advantages of long site investigation programme and close cooperationwith the parallel programme of Swedish Nuclear Waste Management Co (SKB),and to facilitate the flexible, and gradual development of the Safety Case, a portfolioapproach will be employed in the reporting of the Safety Case. In practice, this impliesthat the main components of the Safety Case will be living, fairly independent reportsbased on supporting technical reports. At the various milestones of the programme (e.g.,interim reporting in 2006 and 2009, and the PSAR in 2012), the reports will be linkedand complemented to a Safety Case by means of additional analyses and a summaryreport (Vieno & Ikonen 2005).The Safety Case Portfolio will be compiled from a number of main reports (Vieno &Ikonen 2005) as illustrated in Figure 1-2. It is especially important to notice that thegeo-scientific and scientific reports aim to be as realistic as possible, whereas the radiationsafety-related reports are required to be conservative by the regulations.

7SiteGeoscienceCharacteristicsof spent fuelCanisterdesignRepositorydesignEngineeringProcessesEvolution ofsite and repositoryBiosphereScienceComplementaryevaluationsRadionuclidetransportRadiation safetyand regulationsSummaryFigure 1-2. Main reports of the Safety Case. The nature of the reports is indicated bythe colours of the boxes and the arrows show the most important transfers of knowledgeand data (Vieno & Ikonen 2005).For practical reasons and in order to provide consistent and transparent discussions andassessments, all biosphere matters will be dealt with in a Biosphere Assessment Reportat the main level of Safety Case reporting, instead of distributing them among the Site,Process, Evolution and Radionuclide Transport Reports (Vieno & Ikonen 2005). Elaboratediscussions and descriptions of modelling details will be reported as backgroundreports in the POSIVA Main Report and Posiva Working Report series.Posiva Biosphere AssessmentThe Biosphere Assessment Portfolio was introduced in the Safety Case Planning Report(Vieno & Ikonen 2005): Just as the overall Safety Case consists of main componentreports, of which Biosphere Assessment is one, the biosphere assessment is divided intoa number of more easily manageable components each producing one or more backgroundreports to be summarised and integrated at the Safety Case main level, i.e., inthe Biosphere Assessment Report, into a portfolio. Taking into account the overallneeds of Safety Case documentation and the modelling methods, some re-structuring ofthe original biosphere assessment has been done (Ikonen 2006). Instead of the manyrather extensive biosphere reports, a portfolio containing six thematic folders, eachcomprised of one or more reports, further supported by background reports, and a summaryreport has been organised (Fig. 1-3). The folder structure builds a more robustweb than the earlier plan for biosphere assessment depending largely on subsequentreporting. Possible weaknesses of a part do not migrate so easily throughout the entireassessment, and the workflow can be arranged in a more parallel manner.

8In addition to structuring the Biosphere Assessment Portfolio into thematic folders, thefolders are categorised into three levels: Science Reports aim to form the basis of realisticdiscussion for the assessment and to provide recommendations, in a form that is accessibleto the scientific community, for the further assessment modelling, where numeroussimplifications and assumptions are required. The technical documentation isthe bridge between the recommendations and the actual assessment. It describes theassessment models and the selected data. The assessment reports then include the actualradionuclide transport calculations of the concentrations in environmental media, andthe assessment of exposures to both humans and the other biota. Lastly, the summaryand full conclusions of the biosphere assessment are presented in the Biosphere SummaryReport, shown as the BS Assessment Report in the figure.Overlapping issuesGeosphere-biosphere interface Future human activities Knowledge Quality AssessmentSCIENCETECHNICSSite and its evolutionBiosphere at presentFuture terrainsFuture ecosystemsElement stocks and fluxesModule descriptionsWellAgricultural landTerrestrial ecosystemsAquatic ecosystemsDose calculation modulesTechnical modelling toolsBiosphere processesAquatic/marine ecosystemsWetlandsTerrestrial ecosystemsAgricultural land and other land-usesSoils and sediments and their developmentBiosphere assessment dataUniversal propertiesElement- (nuclide-)specific propertiesDerived site propertiesExposure factors (e.g. intake dose factors)Consumption and other living habitsASSESSMENTCases and variantsExposures of total environmentCalculation case 1Concentrations in environmental mediaCalculation case 2Comparison to natural stocks and fluxesCalculation case NAlternative indicatorsDiverse uses of environmental mediaDoses to members of publicEffects assessment to flora and faunaBiosphere assessment reportSummary (all folders and overlapping issues)Overall knowledge quality assessment (uncertainties and confidence)Conclusions on the long-term radiological impacts of the repositoryBiosphereAssessmentPortfolioFigure 1-3. Folder structure and main components of the Biosphere Assessment Portfolio(Ikonen 2006). This report is part of the Site and its evolution folder.

91.2 This ReportThis biosphere description report is part of the Biosphere Assessment Portfolio presentedabove. The biosphere description provides scientific synthesis of the current stateof the biosphere and the main features of the past evolution at the site. The biospheredescription serves several purposes: It increases the common understanding of the biosphere at the site It supports the modelling of terrain and ecosystems development, as well as theprocess descriptions It supports the selection of site-specific parameter values and distributions in thetransport analyses of radionuclides.This is the first biosphere description report in the series. The next biosphere descriptionreport is being planned to be compiled in 2008/09 to be followed by a third reportin 2011. The schedule of all reports belonging to the Biosphere Assessment Portfolio ispresented in Fig. 1-4.Folder/TopicBiosphere site and evolutionBiosphere at presentBiosphere in future2006 2007 2008 2009 2010 2011 2012Biosphere process reports * * * * * * * * *Model descriptions * * * * * * *Biosphere data db db db db db db dbCases and variantsLandscape models * * * * * * *"What if" cases * * * * * * * *Overall sensitivity and uncertainty * * * * * * * * * *Exposures of total environmentComparison to natural RNsDiverse uses of environmental mediaDoses to members of publicEffects to flora and faunaBiosphere assessment summary report **Safety Case Summary (main report)Intensive workPlanned reportingInterim Summary Reportand Safety Case PlanReport available or in prep.Frozen data set (prel. results)Final report of Safety Case* Intensive work, reporting following the progress (no definite schedule)db Intensive work, internal reporting within database(s)** Within the main level of the Safety Case interim reportingFigure 1-4. Schedule for producing the reports in the Folders of the Biosphere AssessmentPortfolio. The ends of reporting timelines are for published reports. As well thedraft versions of reports can be developed into full reports if deemed necessary, orsome topical reports can be combined, for example, within a modelling case study report,or the reports can be published earlier than indicated. (Ikonen 2006).

10Most of the monitoring activities in the environmental monitoring plan (e.g., in Vieno &Ikonen 2005, Raitio et al. 2007) have now produced at least preliminary results, whichhave been published in several working reports and memos. Previous synthesis reportsconcerning, among other things, the biosphere of Olkiluoto are the Olkiluoto BaselineDescription (Posiva 2003) and Olkiluoto Site Description (Posiva 2005).Due to the extensive work required for the biosphere assessment and the similarity insites to be modelled, it has been deemed beneficial to have close cooperation betweenPosiva and Swedish Nuclear Fuel and Waste Management Co (SKB) in order to enhancethe use of the best resources. Examples of biosphere description-related reportsproduced at SKB are: T. Lindborg & U. Kautsky, 2000. Variabler i olika ekosystem tänkbara att beskrivavid en platsundersökning för ett djupförvar (in Swedish: Potentialvariables of different ecosystems to be described when doing site investigationsfor deep repository). (SKB R-00-19), L. Jerling, T. Lindborg, J. Iseaus, M. Lanneck & R. Schüldt, 2001. Theterrestrial biosphere in the SFR region (SKB R-01-09),U. Kautsky (ed.), 2001. The biosphere today and tomorrow in the SFR area(SKB R-01-27), J. Berggren & L. Kyläkorpi, 2002. Ekosystemen i Forsmarksområdet -sammanställning av befintlig information (in Swedish with an English abstract:Ecosystems in the Forsmark area - summary of existing information). (SKB R-02-08),A. Löfgren & T. Lindborg, 2003. A descriptive ecosystem model - a strategy formodel development during site investigations (SKB R-03-06),Preliminary site description. Forsmark area - version 1.1. (SKB R-04-15),Preliminary site description. Simpevarp area - version 1.1. (SKB R-04-25),T. Lindborg & U. Kautsky (eds.), 2004. Ecosystem modelling in the Forsmarkarea (SKB R-04-71),T. Lindborg (ed.), 2005a. Description of surface systems. Preliminary sitedescription. Forsmark area - version 1.2. (SKB R-05-03),T. Lindborg (ed.), 2005b. Description of surface systems. Preliminary sitedescription. Simpevarp Subarea - version 1.2. (SKB R-05-01),The biosphere at Forsmark. Data, assumptions and models used in the SR-Canassessment (SKB R-06-82), andThe biosphere at Laxemar. Data, assumptions and models used in the SR-Canassessment (SKB R-06-83)The description of the biosphere involves multiple disciplines. The terrestrial and seaflora and fauna, and the overburden, sea water and sea sediments are thus consideredhere, as well as the elements affecting the biosphere (climate, deposition, topographyand its development, and land use). The temporal coverage of this report is from thefirst emerged land area to the emplacement of the first canister in 2020. Geographicallythe emphasis should be on the potential future discharge areas of deep groundwaterfrom the repository, but, in the case of Olkiluoto, this implies studying the whole area.

11The main emphasis is on the description of the current biosphere using the results ofeach sector, thus, for example, the common practice in radionuclide transport modellingwas not taken as a limitation. The goal was to move toward a more quantified description,exemplified in SKB's work, for example, by Lindborg & Kautsky (2004). The constructionof site-specific ecosystem models was started as part of this project. Conceptualecosystem models were presented for land and sea, and quantified whenever possible.It has been reasoned by Lindborg et al. (2006), Löfgren et al. (2006), and Kumbladet al. (2006) that, by placing the emphasis on the flows of matter, the ecological andphysical constraints on a system can be shown to reduce the potential range of futurestates of the ecosystem, hence reducing uncertainties in estimating radionuclide flow,and, in turn, radiological consequences to humans and the environment. As in the SKB'sbiosphere description reports (e.g. Lindborg & Kautsky 2004, Lindborg 2005a,b), carbonwas selected to describe stocks and flows of matter, as it is more or less interchangeableas currency with energy and biomass because of the relative constancy ofcarbon and energy contents in organic matter.Although the presented results are based on extensive sets of measurements, themethodology, monitoring sites and detailed data are mentioned only briefly andreferences to the corresponding Posiva Reports or Working Reports are given.1.3 Delineation of the Study SiteThe studied site is presented in Fig. 1-5. Detailed results concerning the terrainecosystems are presented for the main island of Olkiluoto (approximately 8.9 km 2 ). Forthe larger area (207 km 2 ), preliminary description is given for the dominating landcover,forests, based on satellite image-aided forest inventory data from Finnish ForestResearch Institute. For the sea, the delineation is more difficult. An attempt was madeto calculate results for the potential future lake basins taken on the basis of expectedtopographical development (Rautio et al. 2005, Ikonen 2006), but detailed and spatiallydense measurements were not available from all of the basins. Sea sediment stratigraphywas described from the entire acoustic-seismic study area (see Fig. A-4).

12Figure 1-5. Delineation of the site and future lakes. Borders of lakes 1–3 are based onGIS analyses in Rautio et al. (2005) and Ikonen (2006). Lake 4, which will most likelydevelop into a glo, fell outside the bathymetric data available and needs to bedelineated in detail later.

132 LAND USE ON OLKILUOTO ISLANDOlkiluoto Island lies on the coast of Bothnian Sea, northern Baltic, in the municipalityof Eurajoki, which in turn belongs to the Satakunta province. The closest populationcentres are Eurajoki parish village (16 km east) and town of Rauma (centre 13 kmsouth). Farther away main village of Luvia and city centre of Pori can be found about16 and 32 km northeast, respectively. The nearest smaller villages are Linnamaa (8 kmeast), and Hankkila and Sorkka (9 km southeast; see Fig. 1-5 in Chapter 1). The averagepopulation density of Eurajoki municipality is 16.8 people/km 2 . From the 1960s to date,the size of population has varied between 5,200 and 6,200 (Ollikainen & Rimpiläinen1997, Statistics Finland 2006).The island is relatively flat (see Chapter 5 for topography) and is covered by forest andshoreline vegetation quite typical of such an island in Southwest Finland, if the impactof human activities are ignored (see Chapter 8). Human caused changes in the naturalenvironment have resulted in environmental heterogeneity. There are patches of oldgrowthboreal forest and fresh land uplift coastline, and between them there arecommercial forests and ditched mires, agricultural areas and orchards, “artefact nature”in reservoirs and under power lines, as well as 100% man-made industrial environmentand residential areas. Olkiluoto is one of the two places in the country where electricityis produced by nuclear power. Therefore, a rather significant share of the land use onthe island relates to power plant activities. In addition to the power industry complexitself, there are power-line corridors, roads and reservoirs.The current distribution of Olkiluoto main island into different land-use/land coverclasses is presented in Table 2-1, and the gross estimates for the larger study area inTable 2-2. Due to the recent rapid changes these figures are based on visualinterpretation of aerial photographs taken in June 8, 2005. The FET monitoring plotnetwork (Fig. A-2) was used: it was extended to cover all land-use/land cover classesand intermediate plots were added between the existing plots to create a 50 x 50 m grid.The land on Olkiluoto Island is nowadays owned either by private people, by the Stateor by TVO (Teollisuuden voima Oy) in increasing order of area.

15Kaunissaari, but active commerce with Town of Rauma. Upon closing the saw mill,most log houses were dismantled and transported to a new site in Halssi, Pori.The areas currently owned by TVO were property of the State up until the 1960s(managed by the National Board of Forestry). The area currently occupied by thenuclear power plant passed from the State to TVO in 1973 as an exchange transaction.Since then, TVO has bought areas from Fortum (year 2000), the State (2001) and fromprivate owners (several occasions since 2003).Current Industrial Infrastructure of OlkiluotoNowadays, the western part of the island is occupied by nuclear power production withauxiliary facilities. A small industrial harbour is located on the northern shore of theisland. Power lines run through the northern part of the island, in an approximately 100m wide strip, with a relatively large switchyard. A freshwater reservoir with watertreatment pools is located in the middle of the island for the needs of the power plant.The first nuclear power plant built on the island, Olkiluoto 1, was completed in 1978with a second one in 1980. Construction of the third one started in 2003. In recent years,great changes have occurred, part of which are related to power production and part tonuclear waste disposal (Table 2-3, Figure 2-1).Site investigations for the disposal of spent fuel at Olkiluoto started in 1987. Over theyears, extensive geological, geophysical, rock mechanics, hydrogeological andhydrogeochemical investigations have been carried out, with sampling from outcropsas well as from investigation trenches, deep core-drilled boreholes and several shallowpercussion drilled boreholes (Posiva 2005). These investigations are concentrated to anarea of over 6 km 2 and generally cover most of Olkiluoto Island except for the NPParea, thus adding to the fragmentation of natural environment (see Chapter 2 in Posiva2003 for a detailed list and map of investigations).Table 2-3. Recently finished or ongoing industrial activities on Olkiluoto Island.InfrastructureConstruction timeONKALO area 2003-2006-Rock piling and crushing area (OL3+ONKALO) 2004-Main road 2004-2005Wind generator 2004Gas turbine reserve power plant 2006-2007Main power lines 2005-Roads, pipelines, parking areas etc. 2004-2006New gatehouse and extension to main office 2004-2005New visitor centre 2005-2006Accommodation village 2005-Concrete station extension, laboratory extensionOngoingTraining simulator, warehouse extension, new dumping place Planned

16Figure 2-1. Base maps on Olkiluoto before 2004 (top) and in 2006 (bottom). Most ofthe development has occurred along the main road.Private Land UseThe eastern part of the island consists largely of privately owned forest, summercottages and an area for small-scale agriculture. Within 5 km from the power plant areathere are about 550 cottages (Fingrid 2003). The closest houses are about 3 km from thepower plant area. While the main line of production of the farms in Eurajoki iscultivation, the farms on Olkiluoto (Ilavainen) mainly concentrate on milk production.The nearest farms that concentrate on cultivation can be found in Hankkila Villageapproximately 7 km from Olkiluoto (Ollikainen & Rimpiläinen 1997).

17Nature Protection AreasIn the southern part of the island, there is a nature conservation area consisting of oldforest. The Liiklanperä area was first conserved as an old growth forest (Act 1115/93)and later included in the Natura network. There are some Natura 2000 areas, privatenature conservation areas, areas included in shore conservation programmes, etc. at thevicinity of Olkiluoto as well (Table 2-4). The Natura 2000 areas usually include theolder conservation areas and programmes. There are also other areas of highbiodiversity together with exceptionally intact biotopes on their natural status of whichmost important is the western shoreline area of Olkiluoto Island from Ulkopäänniemi toeast of Tyrniemi, also regionally valuable nesting and migratory area of waterfowl.Expected Changes in Land Use Until the Start of Operation of the RepositoryCurrently, revision and combination work of the land use plans of Olkiluoto Island isongoing. In the revised component master plan, functionality of the energy productioncluster is further supported, taking into account the reservations for the surface facilitiesof the spent fuel repository, for possible new power plant units, and for their securityarrangements. The existing level of recreational dwelling on the island will likely beallowed also in the future. It can be foreseen that the industrial status of the central andwestern parts of the island will be emphasised to some extent even without new powerplant units, and the related major power lines, since the surface facilities of therepository will be built mainly after the nuclear construction license application in 2013.These encompass encapsulation plant either at the nuclear power plant area or close tothe repository entrance, technical auxiliary buildings above the repository, and rockcrush and bentonite storage areas likely next to the existing harbour (Tanskanen &Palmu 2003).Table 2-4. Protected nature areas on Olkiluoto Island and in its vicinity (FinnishEnvironmental Administration 2006a, b; Act 1115/93)Name Natura 2000 Code DescriptionLiiklankari FI0200073 Old growth forest/Natura 2000Rauma archipelago FI0200073 Shore conservation programme/Natura2000Omenapuunmaa FI0200073 Nature conservation area/Natura 2000Reksaari FI0200073 Herb-rich forest/Natura 2000Reksaari-Huhdanpää FI0200073 Nature conservation area/Natura 2000Puuvallinnokka FI0200073 Nature conservation area/Natura 2000Hevoskarta-SäikänniemiNature conservation area, shoreconservationPrami FI0200002 Herb-rich forest/Natura 2000Mäentausta FI0200002 Herb-rich forest/Natura 2000

193 APPLIED AND AVAILABLE DATAWhen compiling reports belonging to the Biosphere Assessment Portfolio, the appliedand available site-specific and site-generic (regional) data must be identified to maintainthe transparency. In the case of this biosphere description report, there are alreadyplenty of site-specific data available, because several projects are in progress andseveral Posiva Reports and Working reports have been published. In Table 3-1, the sitespecificdata applied in this work are listed. The most important monitoring locations atthe site are presented in Appendix A, Figs A-1 to A-4. The available site-specific datanot used here are also identified. The generic cartographic data is presented in Table 3-2. The generic literature used to assign some of the parameters is presented in Table 3-3.The process of compiling this biosphere description report included also theidentification of prevailing gaps of knowledge as well as lack of site-specific data.During the work, it was however noticed that with respect to the description of thecurrent biosphere there were no great gaps in the site understanding, and any questionsthat were raised related to gaps in data rather than gaps in fundamental processunderstanding. The gaps of knowledge will be more evident in the cases of past andfuture development, especially where there is scope for natural processes to be complex.Potentially useful site data currently not available and identified possible improvementsto the existing data sets are listed in Table 3-4. Recommendations for newmeasurements and discussion of their ease of measurement are given in Section 12.4.

20Table 3-1. Applied and available site or region specific data. See Appendix A for thelocations and explanations of measurement points.Domain Data UseClimateWeather observations by the nuclear Description of climatepower plant 1992–2005 (Ikonen 2005,2007)Snow and ground frost measurements Description of climate(Ikonen 2005, 2007)Weather observations from forest plotsFIP04, 2004–2005 and FIP10, 2005Not used so far (short timeseries); Potential use in(Ikonen 2007, in prep.)description of climate andfunctioning of forestChemical depositionEnvironmental monitoring data fromMRK plots (summarised in Haapanen2005, 2006)Radionuclide monitoring data (Ikonen2003, Roivainen 2005, Haapanen 2005,2006)ecosystemDescription of depositionDescription of depositionTopography Lahdenperä et al. 2005 Map, page 12 Description of topographyDigital terrain model data on theOlkiluoto investigation area (Nummela2004)Background material fordescription of topography,suitable for detailed-scaleLand upliftOverburdenGroundwater andsoil waterSea sedimentsShoreline displacement study of Eronenet al. 1995 (Olkiluoto-Pyhäjärvi area)Stratigraphy, soil thickness and chemicaland physical characteristics (Lahdenperäet al. 2005)Soil survey and nutrient analyses byFEH plots (Tamminen et al. 2007)Environmental radioactivity data (Ikonen2003, Roivainen 2005, Haapanen 2006)Stratigraphy and chemical properties ofmires (Ikonen 2002, Lahdenperä et al.2005, Tamminen et al. 2007)Groundwater table (m above sea level)(Lahdenperä et al. 2005)Environmental monitoring data from FIPplots (summarised in Haapanen 2005,2006)Sea sediment stratigraphy and acousticseismic lines (Rantataro 2001, 2002)Sediment accumulation rate (Mattila etal. 2006)Environmental radioactivity data (Ikonen2003, Roivainen 2005, Haapanen 2005,2006)analysesComparison tomathematical model byPåsse (1996a)Mineral soils:profile description,physical and chemicalpropertiesMineral soils:soil type distribution,physical and chemicalpropertiesRadionuclides in soilMires:profile description,physical and chemicalpropertiesGroundwater table,capillary rise, hydraulicpropertiesSoil water properties in thedescription of soilsDistribution andstratigraphy of sea bottomsedimentsEstimate of SAR nearOlkiluotoRadionuclides in seasediments: not used sinceno other chemicalanalyses available

21Table 3-1 cont'd. Applied and available site or region specific data. See Appendix A forthe locations and explanations of measurement points.Domain Data UseTerrestrialvegetationVegetation classification (Miettinen &Haapanen 2002) Description of landcover Polygons used ingeneralisation ofbiomass dataForest inventory by vegetation polygons(Rautio et al. 2004) Description of foreststands Biomass calculationsForest inventory by 100 x 100 m grid (FET;Saramäki & Korhonen 2005) Description of foreststands and mires Biomass calculationsVegetation inventory by FEH plots (Huhta &Korpela 2006) Description of forestand mire vegetation Biomass calculationsNutrient analyses of vegetation by FEH plots Foliage chemistry(Tamminen et al. 2007) Chemical compositionof vegetationEnvironmental monitoring data from FIP plots(summarised in Haapanen 2005, 2006) Changes in vegetationcover Functioning of forestecosystemEnvironmental radioactivity data (Haapanen2005, 2006)Examples of radionuclidesin terrestrial vegetationTime series of environmental radioactivity data(Ikonen 2003, Roivainen 2005)Not used. Data exist fromvegetation and foodstuffsEnvironmental monitoring data from MRK Needle chemistryplots (summarised in Haapanen 2005, 2006)Study of stable elements and radionuclides inshoreline alder stands (Roivainen 2006)Functioning of forestecosystemFauna Baseline bird count (Yrjölä 1997), game Description of faunastatistics (Ikonen et al. 2003, Ranta et al. 2005,Oja & Oja 2006), and small mammal, bat andcarabid beetle inventory (Ranta et al. 2005)SeaecosystemsMonitoring of physico-chemical water quality(Turkki 2006, Kirkkala & Turkki 2005 )Description of sea waterpropertiesMonitoring of primary production,phytoplankton species and biomass (TurkkiDescription of seaecosystem2006, Kirkkala & Turkki 2005)Monitoring of bottoma fauna species and Description of seaLimnicecosystemsbiomass (Turkki 2006, Kirkkala & Turkki 2005)Inventory of coastal macrophytes (Kinnunen &Oulasvirta 2004, Vahteri & Jokinen 1999,Mäkinen et al. 1992, Keskitalo & Ilus 1987,Ekengren et al. 1985)Monitoring of fish stocks (Lintinen 2006,Piispanen & Lintinen 2003)Environmental radioactivity data (Ikonen 2003,Roivainen 2005, Haapanen 2005, 2006)Monitoring of Eurajoki and Lapinjoki rivers(Lehtonen 2005b,c, Kirkkala & Turkki 2005)ecosystemDescription of seaecosystemDescription of seaecosystemNot used. Data exists fromsea water, sea indicators,fish and suspended solidsDescription of rivers

22Table 3-1 cont'd. Applied and available site and region specific data. See Appendix Afor the locations and explanations of measurement points.Domain Data UseLand use Eurajoki spatial description (Ollikainen& Rimpiläinen 1997)Description of populationstructureInventories from FET forest plotnetwork (Saramäki & Korhonen 2005)Background data forestimating land use/land covertypes on Olkiluoto IslandDescription on Kaunissaari Island Description of past land use(Hankonen 2006)Ortho images on Olkiluoto Island (2002,2003, 2004, 2005)Oblique aerial photos on Olkiluoto andnear surroundings (2003, 2004, 2006)on a nearby islandDescription of currentlandscape and its recentdevelopment,Estimation of landscapefragmentation and landuse/land cover types onOlkiluoto IslandDescription of recentlandscape developmentTable 3-2. Applied and available cartographic data.Domain Data UseTerrestrial areas Base map (National Land Survey) Description of current landuse Visual analyses oflandscape fragmentation Identification of relevantMarine areasDigital elevation model, 25 m raster(National Land Survey)Catchment area database (Finnishenvironmental institute)Nautical maps (MaritimeAdministration)Base map (National Land Survey)limnic ecosystemsNot directly used in this work,GIS analyses of landscapedevelopment are reportedseparatelyNot used since database doesnot include catchments in theislands; more useful in laterversions discussing the limnicecosystems in the referenceareas (Chapter 11) Description of bathymetry Support interpretation ofthe sea bottom sedimentdata (see Table 3-1)Estimation of size and field%of the near-catchment area ofEurajoki river, for theestimation of local nutrientload

23Table 3-3. Applied site generic data.Domain Data UseTerrestrial ecosystems,carboncycle estimationsEquations for biomasses of trees andground vegetation (Marklund 1988,Helmisaari et al. 2007, and models byConversion from tree measurementsand plant coveragesto biomassesSea ecosystemsLand useFFRI)Biomass expansion factors (Lehtonenet al. 2004a), leave biomass models forbirch (Parviainen 1999, Ilomäki et al.2003)Models for understorey vegetationbiomass (Muukkonen & Mäkipää 2006)Biomass expansion factors (Lehtonenet al. 2004a), turnover rates ofvegetation (Muukkonen & Lehtonen2004)Turnover rates of vegetation (Lehtonenet al. 2004b, Muukkonen & Lehtonen2004, Starr et al. 2005, Liski et al. 2006,Muukkonen & Mäkipää 2006)Average carbon contents of trees andother vegetation (Hakkila 1989, Nurmi1993, Bolin et al. 2000, Prentice et al.2001)Average carcass weights, C contents,consumption and faeces of moose(Lindborg 2005a), division of moosebody into parts (Kairikko 1981),population structure (Nygrén 1996)Deposition statistics (FinnishEnvironmental Administrationdatabase)Equations for the estimation of N and Pfrom forest and land areas (Rekolainen1989)Municipality statistics (Statistics ofFinland 2006)National Forest Inventory GIS layers,inventories 8, 9 and 10Nature conservation area descriptions(Finnish Environmental Administration2006 a,b)Conversion from standvariables to tree biomassesConversion from standvariables to vegetationbiomassesNet production of trees andunderstorey vegetationLitter production estimatesConversion from biomasses toC amounts.Generation of first estimates ofannual carbon budget ofmoose population in OlkiluotoEstimates of depositionCalculation of local nutrientload from landUpdating the informationcompiled by Ollikainen &Rimpiläinen (1997) Estimation of share offorest in the full study area Description of foreststructure in the full studyarea Monitoring of landscapechanges in the full studyareaListing and basic description ofnature conservation areas inand near Olkiluoto

24Table 3-4. Potentially useful site data currently not available and identified possibleimprovements to the existing data sets.DomainDataClimate No identified lacks in data per se; however, the time series fromthe site are rather shortTopography No very detailed information (lines in 1 m and 5 m steps)Overburden Soil stratigraphy data does not cover whole Olkiluoto siteSoil water Data currently spatially and temporally sparse (two locations,years 2004–2005)Terrestrial ecosystems Vegetation inventories cover the main island only No vegetation cover analyses on shore meadows Mires are few, detailed analyses from Olkiluodonjärvi and somealder and spruce swamps only No site-specific biomass measurements No site-specific measurements of animal weights and contents Almost no site-specific data of fauna by different habitats Some fauna sectors essential for carbon balances have not beeninventoried at allSea sediments Acoustic-seismic line grid sparse and not covering the full studyarea Better data needed from shallow areas No site-specific data of the chemical composition of sediments Erosion/sedimentation areas not knownSea ecosystems Network of water quality, phytoplankton and faunameasurements sparse Phytoplankton data temporally sparse Network of macrophyte measurement lines sparse (located onlyin the target area 3a) Organic carbon has not been monitored Helophytes have not been inventoried No studies or monitoring of zooplankton Little data on currents No site-specific data on the nutrient load from land No site-specific data on the nutrient release from bottomsedimentsLimnic ecosystems Limnic ecosystems currently few, reference areas clearly neededconsidering the future development of the site (see Chapter 11)Land use Up-to-date polygons for exact area calculations on OlkiluotoIsland missing (however, needed tracking data exists butdesultorily), incomplete GIS data on the larger study area at themoment

254 CLIMATE, METEOROLOGY, AND CHEMICAL DEPOSITION4.1 Current Climate and MeteorologyCurrently Olkiluoto has a continental climate, with some local marine influence due toits location on the eastern coast of the Bothnian Sea, which is north of the Baltic proper.In the spring, the sea has a somewhat lowering effect on the temperatures comparedwith those inland, and correspondingly in the autumn provides warmth, so that nightfrosts are less frequent. The long-term statistics for Olkiluoto and the reference sites aregiven in Table 4-1, Figure 4-1, Ikonen (2005), and in Ikonen (2007, in prep.).Table 4-1. Long-term average temperature, annual precipitation and average windspeed at Olkiluoto (1992–2005), at Kuuskajaskari Island 13 km SSW (1971–1995) andat Pori airport 30 km NE (1971–2000) (Drebs et al. 2002, Ikonen 2007, in prep.).Olkiluoto1992-2005Kuuskajaskari1971-1995Pori Airport1971-2000Average temperature 5.8 ºC 5.1 ºC 4.8 ºC- coldest month -4.2 ºC (Feb) -5.0 ºC (Feb) -5.6 ºC (Feb)- warmest month 17.1 ºC (Jul) 15.9 ºC (Jul) 16.3 ºC (Jul)Annual precipitation 517 mm 559 mm 578 mmPrevailing wind direction S SE-S-SW SEAverage wind speed 4.0 m/s 5.5 m/s 4.2 m/sFigure 4-1. Monthly mean and extreme temperatures (left) and monthly totalprecipitation (right) at Olkiluoto for the period of 1993–2005. Solid lines in the middlerepresent the average over the period and dashed lines are values for 2005. The darkerarea shows the range between average minima and maxima temperatures, and theoutermost lines represent the extreme temperatures of each month during the period. Inthe right-hand side the columns represent the average monthly precipitation sum andthe extremes over the period are shown with “error bars” (Ikonen 2007, in prep.).

26These weather data have been recorded at the power plant weather mast at the westernend of the island, 2–3 km from the central investigation area. In June 2004, a 20 mweather mast was erected in the southern central part of the island to provide data closerto the site investigation area and also within the forested area (FIP4), sheltered from thedirect influence of the sea by the highest hills on the island. Comparison of theobservations between these two stations for 2005 is discussed in (Ikonen 2007, inprep.), but the brevity of the time series has not allowed computation of the climatestatistics. Later, in May 2005, a station with a two-meter mast was installed in the forestintensive monitoring plot FIP10 for recording its microclimate, and, in the turn of theyears 2006/2007, another smaller station will be installed to the recently establishedintensive plot FIP11 nearby.Snow Cover and Ground FrostThickness of snow cover and its water content at Olkiluoto have been measuredregularly since 1990. The snow cover is usually less (less than 20 cm snow and 40 mmof water content) than at the closest reference sites (20 cm, Drebs et al. 2002), and theamount of snow varies during winter, with temperatures fluctuating around 0°C (Ikonen2007, in prep.).Ground frost measurements started at Olkiluoto in December 2001. In the most recentfive winters the frost layer has been mainly at a depth of 10…70 cm, depending on theopenness of the area and soil type, and at a depth less than some tens of centimetres atforested points with thick snow cover. The period with ground frost has been fromDecember/January to April/early May (Ikonen 2007, in prep.).Growth ConditionsAs with the other climatic parameters presented in this report, growth season parametershave also been calculated from the data of the weather station WOM1 located in thewestern end of Olkiluoto island, exposed to marine influence. Table 4-2 presentsstarting and ending dates and the duration of the thermal growth season (practicallywhen daily mean temperatures are above +5°C without colder periods of more than 5days a , the corresponding sum of effective temperature (sum of the parts of the dailymean temperatures that exceed +5°C) and precipitation sum over the season.The sum of effective temperature (Table 4-2) is an important factor affecting theprimary production of vegetation, but it needs to be noted that the time series currentlyavailable are rather short.a For a more precise definition, see Ikonen (2007, in prep.), or www.fmi.fi/saa/tilastot_72.html (inFinnish)

27Table 4-2. Annual growth conditions at Olkiluoto in 1992–2005 based on the data ofstation WOM1 (Ikonen 2007, in prep.).Starting Ending Duration Sum of effective Precipitation sumYear date date (days) temperature (ºCd) a of season (mm) a1992 27.4. 9.10. 165 1345 2391993 23.4. 13.10. 173 1151 2981994 22.4. 15.10. 176 1257 1551995 3.5. 30.10. 180 1363 3981996 9.5. 7.11. 182 1262 2741997 6.5. 11.10. 158 1417 2901998 23.4. 27.10. 187 1258 5011999 b 14.5. 13.11. 183 1518 2532000 c 17.4. 25.10. 191 1405 3282001 23.4. 4.11. 195 1526 3692002 21.4. 3.10. 165 1642 2502003 4.5. 18.10. 167 1374 2202004 15.4. 15.11. 214 1439 3122005 d 27.4. 22.10. 178 1465 406Minimum 15.4. 3.10. 158 1151 155Average 27.4. 24.10. 180 1387 307Maximum 14.5. 15.11. 214 1642 501FMI avg e 30.4. 20.10. 173 1200 350afrom daily average/total data rounded to 0.1 unit accuracy; for 1992 and 1993, daily precipitation values of8 and 2 days are missing, respectively, and not accounted herebgrowth period started first time already 18.4. but ended 10 days later; without this the length would be 209d, temperature sum 1551 °Cd and precipitation sum 255 mmcending to just the 5 days period of

284.2 DepositionChemical DepositionThe main chemical characteristics of precipitation (wet deposition), have beenmonitored since June 2003 with a network of rainwater collectors, replaced with snowcollectors during the winter (MRK, see Fig. A-2; Raitio et al. 2007). The interceptionfraction of annual precipitation has varied between 20% and 43% depending on thestand and the year (Table 4-3), being about 33% averaged over all monitoring plots andthe years 2004–2005.The results of deposition monitoring, presented as averages, are presented for 2004–2005 in Table 4-4, separately for open and forested terrain. The foliage of conifers isvery effective at filtering out dry deposition from the atmosphere. Dry depositioncontains varying amounts of gases (SO 2 and NO x ) forming sulphuric and nitric acids atthe surface of needles, thereby contributing to the increase in the acidity of throughfall.In the exchange reactions of base cations b (Ca 2+ , Mg 2+ , Na + , K + ), the tree foliage takesup protons and releases base cations to maintain an electrolytic equilibrium, resulting inhigher concentrations of base cations in throughfall than in open terrain. Thethroughfall also experiences a significant increase in dissolved organic carbon (DOC).This is due to the leaching of organic compounds from living and dead material in thetree crown. In addition to the exchange reactions referred to above, K is also releasedpassively from the living foliage of conifers. Potassium salts are highly soluble, and Kis therefore easily leached from dead needles in the tree crowns before they are shed. Inareas with relatively low nitrogen deposition levels, tree foliage is known to easily takeup nitrate and ammonium from the precipitation. The microflora and epiphytic lichensgrowing in the canopy also use this source of nitrogen. At Olkiluoto this is reflected inmean NO 3 -N and NH 4 -N concentrations in throughfall that are 50% and 67% lower,respectively, than in precipitation collected in open areas. The effects of the forestcanopy can therefore be clearly seen.Table 4-3. Interception of precipitation by the tree canopies in 2004 and 2005.Interception (%) was calculated as ((annual precipitation in the open – standthroughfall)/annual precipitation in the open) x 100. Plots MRK1-MRK3 are Scots pinedominated and plots MRK5-MRK8 are Norway spruce dominated.Year MRK1 MRK3 MRK4 MRK5 MRK6 MRK8 Mean2004 27% 37% 40% 40% 35% 43% 37%2005 20% 34% 38% 24% 26% 29% 28%b Base cations are defined as the most prevalent, exchangeable and weak acid cations in thesoil. Most of them are nutrients for forest ecosystems.

29Table 4-4. Annual average results of wet deposition monitoring in open and forestedterrain at Olkiluoto in 2005 and 2004 (in parenthesis) and at other two intensive forestmonitoring plots in southern Finland (1998–2000) (Haapanen 2006).Parameter OlkiluotoOpen terrainOlkiluotoForestReference areasOpen terrainReference areasForestpH 5.3 (5.1) 5.1 (5.0) 4.9 4.8DOC (mg/m²/a) 823 (1188) 3699 (5025) 1517 5567N tot (mg/m²/a) 341 (361) 289 (262) 395 322NH 4 -N (mg/m²/a) 135 (123) 52 (51) 163 76NO 3 -N (mg/m²/a) 148 (171) 147 (105) 196 154Ca (mg/m²/a) 159 (186) 252 (229) 71 190Mg (mg/m²/a) 44 (75) 88 (99) 20 61K (mg/m²/a) 88 (178) 595 (782) 42 412Na (mg/m²/a) 182 (316) 386 (460) 136 218SO 4 -S (mg/m²/a) 158 (212) 243 (269) 247 287Cl (mg/m²/a) 285 (460) 680 (787) 159 301In these results there is an increase in the pH of water collected in both open terrain andforest in 2005 compared with 2004. Furthermore, the pH in both years is at a levelslightly above the reference areas in southern Finland (location of reference areas: Fig.A-5). The higher values of base cations (Ca 2+ , Mg 2+ , Na + , K + ) compared with thesituation elsewhere in Finland is presumably due to the dense network of forest roadsand the construction work that is taking place in Olkiluoto. These base cationscontribute also to the pH values through exchange reactions. The relatively highdeposition of Cl (with associated Na) is due to the proximity of the sea (filtering of seaspray by pine canopies). The monitoring results are discussed further in Haapanen(2006).A needle wash study was also carried out by in the same wet deposition study plots(MRK; Fig. A-2) in 2003 and 2004 to study the effects of the ongoing constructionwork on deposition on needles. It showed, as summarised in Haapanen (2006), that, inthe case of spruce, there was, for example, more Al and Fe in 2004 than in 2003 andthese elements were deposited on the needle surfaces (the amounts were reduced bychloroform wash). There was more Al closer to the rock piling and crushing area thanfurther away (Fig. 4-2). As well, the Fe concentrations were high close to the rock pilingand crushing area, but at the MRK8 as well, indicating that there might have beenadditional sources. The N concentrations increased between 2003 and 2004, but nitrogenwas used by the trees, thus there were no differences between surface and insideconcentrations. Some rise was seen also in the case of S, but both N and S were close toFinnish reference data. In pine-dominated plots, which are generally located fartheraway from the rock piling and crushing area, and closer to the ONKALO, the constructioneffects were slighter.

30Al mg/kg in C needles of spruce50454035302520151050MRK5 MRK6 MRK8 FIP102003: No wash2004: No wash2003: Chloroformwash2004: ChloroformwashFigure 4-2. Aluminium in current spruce needles in MRK plots (Fig. A-2). MRK5 islocated closest to the rock piling and crushing area, FIP10 is the farthest (Haapanen2006).Radionuclides and Stable IsotopesThe company operating the nuclear power plant, TVO, has monitored radioactivity inthe environment since the 1970s. Radionuclide concentrations in direct wet depositionat Olkiluoto over recent years have been low; however, some traces of ChernobylderivedCs-137 are still detectable (Ikonen 2003, Roivainen 2005, Haapanen 2005,2006).On the basis of sampling in 1989-1995, the isotopic contents of H-2 and O-18 ofprecipitation display some seasonal variation, both being lower in winter than in thesummer. For example, the range of 18 O c of annual precipitation has been –17‰ to –8‰ snow to rain (Posiva 2003, p. 153). A three-year sampling programme for theseisotopes in precipitation and in shallow groundwater was launched in January 2005,supported by the deposition monitoring network (MRK).4.3 Past Climate and VegetationPast Climate StagesIn Finland, glaciations have occurred periodically for at least the last 900,000 years(900 ky; Anttila et al. 1999). There is clear evidence that the timing and extent ofglaciations are largely dependent on small periodic changes in the orbit of the Eartharound the Sun resulting in changes in the solar radiation on the Earth. This is known asthe Milankovitch Theory (Forsström 1999). Occurrence of permafrost is also dependenton climate conditions as discussed by Ahonen et al. (2002) and Gascoyne (2000).c Position of stable isotope composition relative to the global meteoric waterline (GMWL) indicatespotential chemical and physical conditions and processes, and it is usually measured bycomparing the sample to the standard mean ocean water (per mille of SMOW, denoted with ).

31The most reliable evidence for the impact of glacial advances in Scandinavia is obtainedfrom the most recent glaciations, the Saalian and the Weichselian. During the Saalian(which began about 200 ky before present, BP), an ice sheet about 2.5 km thick coveredOlkiluoto Island, and there is no evidence of the island being free of ice during the subsequentSaalian interstadial. Deglaciation at the end of the Saalian period was rapid andsemi-continuous (Anttila et al. 1999, Forsström 1999).Climate warmed rapidly during the Eemian interglacial period beginning about 130 kyBP. Eemian temperatures at Olkiluoto were 4 to 5°C higher than present-day and sealevel is estimated to have been 5 to 6 m higher (Fig. 4-3). In addition, the humidity wasprobably higher than present. The saline Eemian Sea had a seawater temperature closeto that of the present (Anttila et al. 1999).The climate became colder again about 117 ky BP as the Weichselian Period began.The early phases and extent of ice sheets of this era are unknown, but Olkiluoto Islandmay have been free of ice at least periodically, resulting in the formation of deeppermafrost. The largest ice sheet, covering eastern and central Europe, occurred during20-18 ky BP. A broad zone of tundra and permafrost extended over a large part ofEurope at the southern and eastern margins of the ice sheet (Anttila et al. 1999, Ahonenet al. 2002). Maximum ice thickness over Olkiluoto is estimated to have been about 2km during the last glacial maximum (Lambeck et al. 1998). The Weichselian glaciationseems to have ended rather abruptly at 13 ky BP when the climate warmed rapidly totemperatures close to the present. However, the mean annual temperature dropped 5–7°C in a few decades around 11 ky BP with concomitant advance of the ice sheets(Anttila et al. 1999).Olkiluoto became ice-free at about 9.5 ky BP, but was submerged to depths of 100 m bythe Yoldia Sea. At about 9.3 ky BP, the sea became diluted with glacial melt water, andthe freshwater Ancylus Lake formed in the Baltic Sea basin. At about 8.0 ky BP,continued eustatic sea level rise caused sea water to enter the lake through the DanishStraits, and the water in the basin changed slowly to brackish. The Litorina Sea phasebegan with Olkiluoto being submerged by 30–50 m of water. Following the Litorinatransgression there have been no significant changes in the development of the BalticSea basin overall. However, since then, the narrowing of the Danish Straits, associatedwith the post-glacial isostatic land uplift, has caused a decrease in the salinity ofseawater (Anttila et al. 1999).

32Figure 4-3. Ice sheet/glacier extension from the Eemian interglacial to the start of themain phase of the Weichselian glaciation (Lundqvist 1992).Temperatures at 9 ky BP were probably close to the present and summers were likelywarmer. The climate was its warmest at 6-5 ky BP and after that became generallycolder and, from about 2.5 ky BP, more humid (Anttila et al. 1999). Olkiluoto Islandemerged from the Baltic Sea about 3.0 to 2.5 ky BP (Eronen & Lehtinen 1996).Temperature oscillation has also occurred in more recent past. For example, the periodbetween years 1500 to 1850 is known as the Little Ice Age due to the lower averagetemperatures and fluctuating weather. In contrast, the temperatures have risenthroughout most of the twentieth century (Anttila et al. 1999).Past VegetationStudies of pollen, insect and plant fossils have led to estimates of the nature and distributionof the vegetation spread over continental Finland during and after the last deglaciation(Kakkuri & Virkki 2004). The order in which the vegetation evolved after the

33last glaciation is roughly as shown in Table 4-5 and described in brief below. A morethorough account is provided in Kakkuri & Virkki (2004).As the ice sheet started to melt away from the southern and eastern borders, the groundemerging from underneath was gravel, sand and till. Natural forces such as wind, rain,running water, and frost freely sculpted the surface, as no vegetation was present as ofyet. Periglacial conditions prevailed at the ice border with mean annual temperaturesbelow -1°C. This type of climate is characterized by intense frost weathering, theoccurrence of permafrost, patterned ground, and strong winds. Summers at the rim ofthe withdrawing ice sheet were dry and thus enhanced evaporation and groundwaterseepage upward toward the surface. No vegetation could grow before nitrogen started toaccumulate in the soil as a result of bacterial activity. About two hundred years after theice retreated, the ground was taken over by grasses and sedges, and, somewhat later,heath (e.g., Kakkuri & Virkki 2004). Vegetation began to spread over Finland from thesoutheast ordering itself in an east-west direction, and only later in the current southnorthdirection. Treeless vegetation phases are thought to have lasted for hundreds ofyears. The first species of tree was dwarf birch, which appeared about 10,000 years ago(e.g., Helmens et al. 2000). It then took 1,000 years for other birch species to reachLapland. Around the same time, aspen, willow, and alder appeared. After anotherthousand years (about 8,000 years ago) the Scots pine arrived. Hardwood trees and evenhazel spread across southern Finland during a short period (Table 4-5). As the climatebecame colder, spruce emerged from the southeast for about 5,500 years ago andcovered the whole country within 2,500 years. The vegetation evolution is roughlyillustrated in Figure 4-4.Table 4-5. Succession of vegetation in Finnish inland areas during and after the latestdeglaciation (Kakkuri & Virkki 2004, Tolonen & Ruuhijärvi 1976).Years ago Climate type Characteristic Vegetation type11 500 Preboreal Treeless tundra vegetation11 300 Preboreal Bushes, dwarf birch11 200 Preboreal Birch10 200 Boreal Pine8 800 Atlantic Alder, Hazel7 400 Atlantic Hardwood trees5 800 Subboreal Spruce2 600 Subatlantic Pine, Spruce

34Time aBP11 000 10 500 10 000 9 500 9 0006 000 5 500 3 000presentContinentalFinlandCoast, such asOlkiluotoGravelTundra veg.Dw arf birchPineAlderSpruceBirchFigure 4-4. Vegetation evolution after deglaciation for continental Finland and forcoastal areas such as Olkiluoto (Posiva 2006). The figure is based on data fromKakkuri & Virkki (2004), and Tolonen & Ruuhijärvi (1976).In the presence of an ice sheet, the surface ecosystems are expected to contain hardlyany flora and fauna species, in a way similar to areas of perennial ice (e.g., over 3000metres in altitude or near the poles) and the human population is likely to be absent orsparse. But even during cold climatic phases, vegetation may exist at the ice border. Incoastal Antarctic regions, soil formation and chemical weathering occur to a greaterextent than formerly predicted. For example, in areas with a mean annual temperature of-9.3°C and six weeks of the summer with temperatures above freezing, plantcommunities of mosses, lichens and algae can establish and grow (Beyer et al. 2000).The coasts of Finland, including Olkiluoto, experienced a slightly different evolution atthe end of the glaciation period. The ice sheet retreated from the Olkiluoto area forabout 9,500 years ago (Anttila et al. 1999). The area remained depressed from theweight of the ice and was submerged for about 6,000 years; due to isostatic adjustment,the Olkiluoto area emerged from the sea only 2,500–3,000 years ago (Eronen &Lehtinen 1996).Instead of the vegetation succession described above, land emerging from under an icesheet or from the sea may, under certain climate and topographical conditions, be takenover by mire vegetation, called primary mire formation. Most of the peatlands inwestern Finland were initiated on land uplift shores (Aario 1932). The fresh soilsurface, which emerged from the water, was partly occupied by mire vegetation anddeveloped into brackish marshes. The land uplift also segregated former bays, whichdeveloped into lakes. Some lakes were filled-in and overgrown by mire vegetation,converting them into peatlands. The primary mire formation and the overgrowth ofwater bodies were the starting points of larger mire areas, which reached their laterscale by expanding over adjacent forests. Forest paludification took place duringespecially humid climatic periods and was also promoted by forest fires and stormdamage (Ikonen et al. 2004).

355 TOPOGRAPHY, BATHYMETRY AND SHORELINE DISPLACEMENT5.1 Current TopographyThe average elevation of Olkiluoto is about +5 m above mean sea level. The highestpoints of the investigation site are Liiklankallio +18 m, Selkänummenharju +13 m andUlkopäänniemi +12 m. A topographical map is presented in Figure 5-1. The bedrocksurface (Figure 5-2) is more variable, but the ground surface is still quite level, even atplaces where the bedrock surface changes abruptly. The depressions of the bedrocksurface are filled with a thicker layer of till and the bedrock highpoints stick through themodest soil layers, as a result of the last glaciation (Figure 5-3) (Lahdenperä et al.2005).5.2 Current BathymetryThe waters around Olkiluoto are generally shallow with open sea beyond the few rockyinlets at the western end of the Island and only a few islands to the north (Figure 5-4).Due to the openness to the sea, the winds affect water currents (Posiva 2003). Two ofthe largest rivers in the Satakunta province, the Lapinjoki and the Eurajoki discharge –on average 3.6 and 9.6 m 3 /s, respectively (Kirkkala & Oravainen 2005) – to the seanorth and east of Olkiluoto, increasing the concentrations of nutrients and solids,especially at the river mouths. The cooling water intake and discharge of the nuclearpower plant significantly affect the temperature and the currents only in their closevicinity. The cooling water flow is about 60 m 3 /s (Posiva 2003).

36Figure 5-1. Topography at the Olkiluoto Island, with contour spacing of 1 m (greylines) and 5 m (black lines) (Lahdenperä et al. 2005).

37Figure 5-2. Bedrock surface (m, above sea level), red corresponds to +17 m above sealevel and light blue areas when bedrock surface is below sea level (Lahdenperä et al.2005).

38Figure 5-3. Thickness of the overburden according to Vaittinen et al. (2003) with thenew investigation points from the years of 2003–2004 providing information of theoverburden thickness (Lahdenperä et al. 2005).

39Figure 5-4. Bathymetry of the sea areas near Olkiluoto. Profiles indicated arediscussed in Chapter 7.

405.3 Land Uplift and Shoreline DisplacementThe most obvious consequences of postglacial adjustments in Fennoscandia are the landuplift along both sides of the northern part of the Baltic Sea and the concomitant retreatof the shoreline. The net (or apparent) land uplift is the result of the glacio-isostaticcomponent i.e., a change in the level of the land mass and the (global or regional)eustatic component i.e., a change in the level of the sea, due to the changes in thevolumes of polar ice and sea basins, for example.The relationship between land uplift, eustatic sea level change and the water balance ofthe Baltic Sea determines, whether the sea level is generally rising, maintaining stableor lowering in the current coastlines (Johansson et al. 2001). The Fennoscandianlithosphere is still undergoing postglacial rebound (Påsse1996a, b) and the rebound stillhas about 20,000 years to run. Uplift can be considered constant in the timescale of afew centuries (Ekman 1996).Currently it is widely agreed that the Earth’s climate is warming up and that the sealevel is rising. The mean sea level, which appears to have been steady for the last3,000–4,000 years, has shown a linear rise of between 1 to 2 mm per year over the last100 years (IPCC 2001, Johansson et al. 2001, Ruosteenoja 2003). According to ICCP(2001), global average sea level will rise 0.11-0.77 m in the next century.Påsse (1996a) fitted a mathematical approximation function of various historical landuplift data for both land uplift and global sea level rise for the part of Scandinaviacovered by ice during the last glaciation. Löfman (1999) adapted the mathematicalapproximation function for the glacio-isostatic land uplift in the Olkiluoto area from20,000 years ago to 10,000 years AP (Figure 5-5).Eronen et al. (1995) studied past shoreline changes in southwestern Finland. Theycollected sediment samples originating from the last 8,000 years from 14 lakes atdifferent altitudes in the area between Olkiluoto and Lake Pyhäjärvi, 40 km away. Thetime when the present-day lakes were isolated from the Baltic Sea was determinedusing diatom analyses and radiocarbon dating and the shoreline displacement curve ofthe study area was drawn. Results of the study indicate that uplift has proceeded in aneven manner, and has been slowly decreasing during the past 8,000 years. The currentapparent land uplift rate at Olkiluoto is 6 millimetres per year (Eronen et al. 1995), or6.8 mm/y as the isostatic component (Kahma et al. 2001, Löfman 1999). Right after theice sheet retreated, postglacial uplift was over ten times faster than at present.Due to this postglacial uplift and shallow coast areas, sea bottom sediments arecontinuously emerging from the sea with a rapid primary succession along the shores.Furthermore, along the shallow shores of Olkiluoto, especially in geolittoral regions, theamounts of common reed are increasing naturally (Fig. 5-6), resulting in paludificationof coves and accumulation of organic matter in shallow and nearly-stagnant water. Thiswill result in a faster apparent shoreline displacement than mere land uplift or changesin sea level would yield. In addition, eutrophication of the Baltic Sea speeds up theprocess (Miettinen & Haapanen 2002).

41Figure 5-5. The postglacial land uplift and the global sea level rise in the Olkiluotoarea. Curves represent the equations in (Löfman 1999, p. 40) based on the data byPåsse (1996a). Circles denote the empirical data by Eronen et al. (1995).Figure 5-6. Aerial photo on a typical shoreline showing common reed coloniesbetween Olkiluoto Island and the mainland (photo: Teollisuuden Voima Oy/LentokuvaVallas Oy, Hannu Vallas, 7 June 2006).

425.4 Past Topographical Development at OlkiluotoThe Olkiluoto site is one of the most recent areas that has emerged from the sea afterthe last glaciation In Finland. In the following, main stages in the development ofOlkiluoto Island are summarised after Mäkiaho (2005) and illustrated with newelevation model manipulations to a larger area, following the same parameterisation asin Mäkiaho (2005). These manipulations are part of the simulations for the terrain andecosystems development model of the site to be reported in early 2007 (Ikonen 2006).The first summits of Olkiluoto rose above the sea level about 2,800 years BP and stillsome eight hundreds of years later there existed about ten separate small islands, whilemost of the present land areas lay still under the sea-level (Fig. 5-7). At 2,000 BP, thehighest point of Liiklankallio lay 5.6 metres above sea level. Most of the islandsemerged from the sea at 1,500 BP (Mäkiaho 2005).A thousand years ago many of the initially formed small islands have interconnectedinto one bigger island and this island begins to get its shape. The islands also lost theirglaciogenic sediments as the waves washed the loose deposits away (Mäkiaho 2005).Most of these bare rock surfaces are those facing west, which has been the direction ofmost effective wave action during this washing stage (cf. Seppälä 2005).Five hundred years ago the Olkiluoto area resembled pretty much that of today (Fig. 5-8) but the shoreline lay still some hundreds of metres from the present, farthest in thewest. The current headland of Otapää was still a separate island as well as Liiklankari,which has only very recently become a part of Olkiluoto Island.During the next century no dramatic changes will take place. The development of theshoreline will induce changes in the local biosphere conditions, such as biospheresuccession, sediment redistribution (sedimentation and re-suspension/erosion) andgroundwater flow. These will in turn influence the positions of the potential deepgroundwater recharge and discharge from the repository.

43Figure 5-7. Topography of the Olkiluoto area at 2,000 BP (Olkiluoto terrain andecosystems development model 2006).Figure 5-8. Topography of the Olkiluoto area at 500 BP (Olkiluoto terrain andecosystems development model 2006). The red rectangle indicates the area presented inFigure 5-6 above.

456 OVERBURDEN6.1 GeneralThe most common mineral sediment, till, is formed from bedrock, preglacial sedimentsand “in situ” weathered bedrock when the slowly flowing glacial ice dislodged, crushedand ground the mineral matter. The melt waters from glaciers and flowing waters ingeneral, have abraded, rounded and sorted the sediments during transport, andaccumulated them in glaciofluvial deposits. The finest material is carried in suspensionand deposited as silt and clay at the bottom of water basins (Koljonen 1992).The soil types are characterised by different mineralogical, chemical, physical andbiological parameters and thus are heterogeneous. Microbiological populations are animportant component of soils and sediments. Another important property is thedistance between the soil surface down to the water table, which can vary fromcentimeters to meters and can change rapidly in response to surface water infiltrationand runoff. The transition from surface soil to overburden and from overburden tobedrock and vice versa, is not abrupt (e.g., Lahdenperä et al. 2005).6.2 PodzolisationIn Finland the predominant soil-forming process, podzolisation is a slow process thatstarted on the surficial parts of mineral soil after Weichselian glaciation, about 10,000–9,000 years ago in the supra-aquatic areas of northern and eastern Finland. Due to theevolution of the Baltic Sea, at Olkiluoto, the podzol soil layers started to develop about3,000–2,500 BP (Eronen & Lehtinen 1996). Starr (1991) observed that, at theselatitudes, mere podzol soil formation can take up to 500–1,500 years.Figure 6-1 illustrates the main structure and processes of the podzol soils. The highmoisture content, high incidence of anaerobic conditions and poor decomposability ofplant litter result in gradual accumulation of organic layer comprising acidic, partiallydecomposed litter and humus in the surface layer. Below the organic layer is a lightcoloured eluvial horizon with a reddish illuvial horizon below that. The eluvial horizonwill be leached by acid percolation water and will become low in base cations. Iron andaluminium are removed as colloids incorporated into clay minerals or as organometalliccomplexes, mainly in the illuvial horizon. Chemically modified surficial horizons areunderlain by relatively unaltered parent material.The most important factors affecting structure of podzol soils are the susceptibility ofminerals to weathering, grain size, climate, and topography and runoff conditions. In thesoil solution, the presence of hydrogen ions activates cation exchange reactions betweenclay minerals, organic matter and root nodules. Cation exchange on the surfaces of soilparticles is the most important buffering process in humus and eluvial horizon (Brady1984, Andersson 1988).

46Figure 6-1. Structure and horizons of a podzol profile. Owing to electrolytes dissolvedfrom the eluvial horizon (A-horizon), the pH of the runoff water increases in the illuvialhorizon (B-horizon) and in the transition zone (between B- and C-horizons),precipitating aluminium, iron and silicon compounds. Cation exchange is most intensein the humus and eluvial horizons, and the chemical weathering of minerals in thetransition zone and weakly altered parent material (C-horizon). Figure from Kähkönen1996. Modified after Stahler (1970) and Jacks et al. (1984).6.3 Physical Properties of Soils on OlkiluotoSoils at Olkiluoto are weakly developed due to short time span of less than 3,000 years(Eronen & Lehtinen 1996). On the basis of silvicultural inventory in 2003, the mostcommon soil types in the Olkiluoto Island area are fine-textured (53%) and sandy(39%) till (Table 6-1). The other types are gravelly till (4%) and peat (3.4%) in additionto one percent of outcrops (Rautio et al. 2004). Some Litorina and Ancylus clay areas

47exist in addition to the areas of (sub-) d recent mud cover at the northern and southernside of island (Posiva 2003).A soil survey of 94 Forest Extensive High level plots was carried out in 2005 (FEH;Tamminen et al. 2007, see locations in Fig. A-1). These plots were inventoried for theirhumus, mineral soil (0–60 cm) and peat (0–30 cm) types. According to the survey, themost common soil types at Olkiluoto are weakly developed (often podzolised) coarse tomedium coarse Arenosols or fine-textured Regosols, shallow Leptosols and Gleysols echaracterised by shallow groundwater. In general, the groundwater in FEH plots laywithin the depth of 0 to 40 cm on 15 plots, and 24 sample pits out of the 85 mineral soilones were under 50 cm deep due to bedrock, big boulders or groundwater. Organiclayer was classified in most cases as mor, peat or mull-like peat. The thickness of theorganic layer varied from 2.3 to 21.1 cm and in the peatland from 6 to 115 cm. Themedium particle size class in mineral soils was very fine sand.In addition to the FEH soil survey, data exists from the deep soil pits KK1-KK13 dugby excavator (see Fig. A-1 for locations and Fig. 6-2 for an example of a deep soil pit).Physical and chemical properties of the KK pits have been investigated from differentdepths using standard procedures. The total depth of test pits varied from 1.6 m to 4.55m (Hagros 1999, Lintinen et al. 2003, Lintinen & Kahelin 2003). Two chemicalextractions were used for samples to emulate different environmental conditions. Inaddition, mineralogical composition from the two grain size fractions was determined.The detailed description is presented in Lahdenperä et al. (2005). The soil types atOlkiluoto were also mapped along two investigation trenches: TK8 and TK9 (Fig. A-1).The lengths varied from 350 to 730 m and depths from 1.7–6 m (Huhta 2005).Table 6-1. Distribution (%) of soils and forest site types (with Finnish abbreviations) onthe main island of Olkiluoto (data from Rautio et al. 2004).Till Peat ExposedGravel Sand FinetexturedSedge Sphagnum bedrock TotalGroves (Lh) 0.0 0.0 0.0 0.0 0.0 0.0 0.0Grove-like/herb-rich 0.0 0.1 19.4 1.4 0.0 0.0 20.9(OMT)Fresh/mesic (MT) 0.2 28.1 33.0 1.8 0.0 0.0 63.2Dryish/Sub-xeric (VT) 0.1 10.2 0.0 0.0 0.0 0.0 10.3Dry/Xeric (CT) 3.3 0.0 0.0 0.0 0.4 0.0 3.7Extr. infertile (ClT) 0.0 0.0 0.0 0.0 0.0 0.0 0.0Rocky, sandy 0.5 0.0 0.0 0.0 0.0 1.4 1.9Total 4.2 38.4 52.4 3.2 0.4 1.4 100.0d Sub-recent means that the mud lies under the mud that is currently developinge Soil types according to the classification by FAO-UNESCO 1988. Arenosols are sandy soilsfeaturing very weak or no development, Regosols are soils with very limited soil development,Leptosols are very shallow soils over hard rock or in unconsolidated very gravelly material,Gleysols are soils with poor drainage and excess water in the subsoil for most of the year.

48The results of refraction seismic measurements have been used to measure the thicknessof the overburden above bedrock. Lehtimäki (2001, 2003) provided an integrated interpretationof the available refraction seismic data covering the whole Olkiluoto Islandand more detailed on the central investigation area.Figure 6-3 presents two vertical cross-sections presenting the stratigraphy on the centralisland (see Fig. A-1). In the investigated test pits, till is sandy till, containing some clay,sand, gravel and weathered layers. Till is weakly laminated and quite rich in fines. Insome pits till is more stony or compact, especially in deeper horizons. In some isolateddepressions also fine grained glacilacustrine sediments were observed. In the test pitsclay (< 0.002 mm) content in general varied from 7% to 14%. In one shallow test pit theclay content was 48% in the depth of 0.5 m. The organic matter content of till was low,less than 1.2%. Density of soil particles was 2.8–3.0 mg/cm 3 and specific area 2.3–15m 2 /g. Till in the study area can be described as a basal till deposited by actively flowingbasal conditions of the ice sheet (Lintinen et al. 2003, Lintinen & Kahelin 2003).Observations of disintegrated rock layers of rock debris between solid bedrock andoverburden are found in the test pits along the research trenches TK8 and TK9. Thedepth of these layers varied from some 10 cm to 2–3 meters (Huhta 2005). Detailedresults are presented in the report by Lahdenperä et al. (2005).Figure 6-2. Test pit KK13 (Photo from Keskitalo 2004).

49Figure 6-3. Overburden thickness (m) in the central investigation area and illustrativeoverburden profile lines (not at the same scale). The black columns show theobservations; the reddish part is till and grey bedrock. The presentation is designed byprojecting the bedrock surface, soil type and ground water table from the shownobservation points to the cross-section planes (Lahdenperä et al. 2005).

506.4 Geochemistry of Soils on OlkiluotoAccording to Tamminen et al. (2007; soil survey by FEH plots), soils at Olkiluoto wereacid. The organic layer pH ranged from 3.7 to 4.4 (from dry mineral soil sites to grovesor herb-rich forests, respectively). The concentrations of calcium, magnesium andsodium in the surface soil were higher at Olkiluoto than on nine control plotsinventoried in inland locations within the same campaign (see Fig. A-5). These controlplots were not exactly similar in forest characteristics, but were measured to serve asbenchmark in monitoring of possible changes on Olkiluoto soils. Concentrations of basecations, especially calcium, correlated with the forest site type. In alder stands atOlkiluoto, the concentrations of base cations were even 30 to 40 times higher than ininland pine stands. These alder sites are the youngest, emerged some hundred years agofrom the sea and still containing sea salts rich in sodium and magnesium and maybe stillgetting sea salts as droplets or spray during storm events. The differences betweenOlkiluoto and the control plots decreased toward deeper soil layers.Both the Olkiluoto mineral soil FEH plots and the control plots had higher nitrogenconcentration and lower C/N ratio than Finnish forest soils in average, meaning highersoil fertility (Table 6-2; see average values for Finnish mineral soil sites in Tamminen2000). C/N ratio of the organic layer discriminated between mineral soil site types andalso between dominating tree species (Table 6-3). Soils in the alder stands containedmore nitrogen compared with other stands, and had a very low C/N ratio in the organiclayer, but also in the conifer stands nitrogen status was better than on average in Finnishforest soils, where C/N ratio was in the organic layer 27 on the OMT sites and 37 on theMT sites (mineral soils; Tamminen 2000). According to Starr (1991) it takes a shortertime (200 to 300 years) for the N concentrations to reach equilibrium compared with Cconcentrations (> 750 years) after the land has emerged from the sea.Total elemental concentrations were determined only from the organic samples. Allelements, except for Mn, seemed to have higher concentrations at Olkiluoto than on thecontrol plots.

51Table 6-2. Total concentrations (%) of carbon and nitrogen and C/N ratio by soil layerin the 85 mineral soil FEH plots. Values of the control plots (n=9) are in italics (Tamminenet al. 2007).Organic0-10cm10-30cmn C N C/NMin 85 20.4 17.5 1.08 0.71 13.5 23.5Median 39.5 40.2 1.62 1.34 23.2 25.4Max 48.7 41.6 2.71 1.73 36.6 35.2Min 76 0.5 1.1 0.05 0.06 9.0 17.0Median 1.7 3.4 0.11 0.15 15.7 20.6Max 7.3 5.2 0.46 0.31 22.3 24.3Min 75 0.2 0.7 0.03 0.04 6.5 12.3Median 0.6 1.8 0.06 0.10 11.4 18.3Max 5.8 2.5 0.45 0.13 22.9 20.3Table 6-3. Total concentrations (%) of carbon and nitrogen and C/N ratio by soil layerand by dominant tree species in the 85 mineral soil FEH plots. Values of the controlplots (n=9) are in italics (Tamminen et al. 2007). Equal mean values are marked withthe same letter (Bonferroni test).Organic0-10cm10-30 cmn C N C/NPine 30 37.5 30.2 1.47 a 1.03 25.6 c 28.9Spruce 40 39.7 37.6 1.73 a 1.47 23.4 bc 25.8Birch 10 36.9 1.73 a 21.4 bAlder 5 36.0 2.32 b 15.5 aPine 22 2.0 1.8 0.12 0.09 16.8 19.5Spruce 39 2.2 3.6 0.14 0.18 16.2 20.6Birch 10 2.1 0.14 15.0Alder 5 2.0 0.15 13.2Pine 22 1.1 1.1 0.08 0.06 12.8 17.6Spruce 39 0.7 1.9 0.06 0.11 11.6 17.9Birch 9 0.8 0.06 11.8Alder 5 0.7 0.07 10.0The soil samples in the KK sample pits dug by the excavator (Lahdenperä et al. 2005)were not taken along the podzol soil horizons, thus the data did not give completeresults on the soil geochemistry and processes. The soil data was divided into twocategories: surface mineral soil horizons and C-horizon (basal till). Two differentchemical analyses were used: strong nitric acid leach and synthetic rainwater leach. Theconcentrations obtained with strong nitric acid leach are several hundreds to thousandstimes higher compared with synthetic rainwater leach (Table 6-4).The greatest deviations in soil pH are due to the variation in humus and clay contents(Räisänen 1989). Water content and organic matter patterns were quite similar in bothsurface soil horizons and basal till. The anion concentrations (Cl, F, NO 3 ) leached bysynthetic rainwater were extremely low or under detection limit.Aluminium and iron concentrations were higher for both types of leaches in the surfacehorizon than in the basal till, probably due to enrichment in the illuvial horizon. For thebase cations the concentrations were opposite, especially for Ca and Mg. Due to young

52soils at Olkiluoto, the base cation concentrations are expected to decrease in the futuredue to surface soil weathering, leaching and removal of nutrients.Strontium concentrations in surface and C-horizon were low using both leaches. Thevariation in solubility of strontium is similar to sodium, calcium and potassium,indicating that strontium mainly incorporates in plagioclase and potassium feldspars,which are highly resistant to weathering. Acidity of soil increases the leaching ofstrontium.The concentrations of uranium and caesium were low using synthetic rainwater leach,but using nitric acid leach they were almost the same as, or even higher, than in averageFinnish soils. Uranium concentrations were higher in surface soil horizons than in C-horizons. Although the investigation area at Olkiluoto was quite small there was a quitelarge variation in element concentration. A more detailed description is presented inLahdenperä et al. (2005).Table 6-4. Geochemical characteristics of the solid phase of soil samples fromOlkiluoto (median, range of values and number of samples). The material is sandy till.(Lintinen et al. 2003, Lintinen & Kahelin 2003, Lahdenperä et al. 2005).Synthetic rainwater leachNitric leachVariables Surface soil N C-horizon f N Surface soil horizons N C-horizon NhorizonspH g 6.5 (4.0-8.0) 19 7.5 (6.5-8.0)Anions, mg/kg hCl (

536.5 MineralogySoil samples were homogeneous in the mineralogical composition. In order ofabundance, quartz, plagioclase, K-feldspar, mica, chlorite and hornblende were typicalof the < 2 mm fraction, and correspondingly illite, hornblende and chlorite for the finefraction, i.e., < 2 µm (Lintinen et al. 2003, Lahdenperä et al. 2005).6.6 Hydrogeochemistry of overburdenResults from Groundwater TubesSampling of shallow groundwater from the groundwater tubes (PVP) and shallow wells(PP, PR), summarised in Posiva (2003) and Tammisto et al. (2006), has continued.Since 2002, a total of about 198 shallow groundwater samples have been analysed untilNovember 2006.The shallow groundwater is mainly fresh and locally brackish, with the correspondingwater types being Ca-HCO3 and Na-Cl. The pH of the samples varies from 5.1 to 8.0.The samples collected since the Baseline report (Posiva 2003) correspond to theprevious results, and also show evidence of fresh water leakage from the Korvensuoreservoir. Seasonal trends in pH and alkalinity are also observed. For example, all pHvalues measured in the spring of 2002 were slightly lower than the values incorresponding samples in the autumn of the same year. Clear seasonal changes were notobserved for any other chemical parameters (Posiva 2003). The new samples also showsimilar behaviour (Posiva 2005).In overburden and shallow bedrock (< 10 m), water-solids interactions are infiltratingmeteoric water without any notable mixing with older groundwater types. Salinityclearly increases in shallow groundwater in the low-lying southern parts of the sitewhere sampling points are situated in the vicinity of bedrock depressions andinterpreted fracture zones, thus indicating possible discharge areas for deepgroundwater (Posiva 2003, Pitkänen et al. 2004).The chemical evolution of infiltrating groundwater is characterised by biogenicrespiration of organic carbon in the thin overburden with possible calcite dissolutionand some silicate hydrolysis. As well, initial oxidation of sulphide minerals to dissolvedSO4 seems possible. In the overburden, the water type changes to HCO3-rich, and pHrises above 7 (Posiva 2003, Pitkänen et al. 2004).The transition between the shallow and deep groundwater regimes occurs at a veryshallow depth, typically within the first 15–25 m. The shallow underground biosphere isdominated by oxygen consuming micro-organisms that will block oxygen migration todeeper groundwater. The groundwater depression caused by construction of ONKALOwill most probably move the borderline between the shallow and deep undergroundbiosphere downwards (Pedersen 2006).

54Soil Solution Results from Forest Intensive Monitoring Plots (FIP)Chemical composition of the soil solution has been monitored during the snow-freeperiod in a Scots pine stand (FIP4) and a Norway spruce stand (FIP10) at Olkiluoto(Fig. A-2). Soil solution was sampled at different depths down the soil profile, thusproviding information about soil formation processes. Two sampling techniques wereused for sampling soil solution in the two stands. The results of the soil solutionmonitoring in 2004 (FIP4 only) and 2005 (both locations) were originally reported byJohn Derome (Finnish Forest Research Institute) in a memo and summarised resulttables are presented in Haapanen (2006).Scots Pine Stand (FIP4)The acidity of the soil solution (pH 4.1–5.5) was relatively similar in both monitoredyears and comparable to a reference site in Tammela (see location in Fig. A-5). The lowconcentrations of nitrogen were primarily due to the fact that nitrogen is the main factorlimiting tree growth in coniferous stands in Finland; the available nitrogen (NH 4 andNO 3 ) mineralised from the organic layer is rapidly taken up by the roots of the trees andground vegetation. The low sulphate concentrations at all other depths were relativelysimilar to those at the reference site.Chloride concentrations were high (1.15–6.9 mg/l) at all depths due to a considerableinput of NaCl in deposition derived from the sea. As well, the concentrations of Na atall depths continued to be elevated, presumably due to the proximity of the sea. Theconcentrations of the important plant nutrients (Ca, Mg, K) showed a decrease in 2005compared with 2004 at all depths, and were approaching the levels for the referencesite. This suggests that there has been a short-term flush of these nutrients. Phosphateconcentrations were very low in the soil solution as is the case at most forested sites inFinlandThe concentrations of total Al at all depths were similar in both 2004 and 2005, andhigher than the values for the reference site at deeper depths. The concentration of Al 3+ ,which is a toxic form to plant roots and mycorrhizas, was still extremely low at 5 cmdepth, but considerably higher at the other depths compared with the reference site. TheFe concentrations showed considerable year-to-year variation. The Mn concentrationsin 2005 were very similar to the concentrations in 2004. The Si concentrations at depthsof 5 and 10 cm in 2005 were considerable higher than the corresponding values in 2004.Most heavy metal concentrations were below the limit of detection, the exception wasZn, which decreased slightly in 2005 compared with 2004 (Haapanen 2006).Norway spruce site (FIP10)The acidity of the soil solution at all depths was lower than that in the reference stand inTammela, especially in the mineral soil horizons. The main reason for this is that thesoil at Olkiluoto is considerably younger, and therefore contains higher concentrationsof base cations. The DOC concentrations were considerably higher than in the referencesite, but not excessively high for organic matter-rich spruce forest soils. The higherDOC concentrations are probably also associated with the disturbance in the soil caused

55by installation of the lysimeters. The relatively high levels of total nitrogen closely followedthe pattern for the DOC concentrations. Sulphate concentrations were relativelylow at 5 cm depth, but strongly elevated at 20 and 30 cm compared with the referencesite. Phosphate concentrations were at approximately normal levels (Haapanen 2006).As was the case in the pine stand, the chloride (2.2–19.0 mg/l) and Na (3.3–17.8 mg/l)concentrations were high at all depths due to the input from the sea. The concentrationsof Ca, Mg and K were strongly elevated at all depths in the soil. The concentrations oftotal Al, Al 3+ and Mn were relatively similar to the reference values at all depths, whilethose of Fe and Si were strongly elevated at depths of 20 and 30 cm. The high siliconvalues are undoubtedly due to the young age of the soil; silicon plays an important rolein soil-forming processes under coniferous tree species. The main heavy metal concentrationsat all depths were below the limit of detection at both Olkiluoto and at the referencesite, with the exception of Ni and Zn (Haapanen 2006).Hydraulic Properties of the OverburdenOver the majority of the island, there are less than 2 m of overburden above the averagegroundwater surface, which is similar to the typical fluctuation of groundwater level(Posiva 2003). In other words, the groundwater level can be close to the ground surfacefor at least some periods during some years over most of the island, excluding the highestelevations. Areas with a groundwater level close to the ground surface are shown inFigure 6-4 (Posiva 2005). On the basis of slug tests in overburden tubes (PVP) and shallowwells (PP), the hydraulic conductivity of the overburden is in the range of 10 -5 –10 -9m/s and varies with the grain size distribution, especially with the clay content (Hellä etal. 2004).

56Figure 6-4. Thickness (m) of ground layer, soil and partly bedrock, above the long-termaverage groundwater table. On low areas, some springs and adjacent to constructionsthe hydraulic head is above the ground surface.The depth of the water table at the various groundwater observation points is presentedin Figure 6-5 (Lahdenperä et al. 2005). For each observation point maximum, minimumand mean results are indicated. The figure implies that, in the majority of cases, themean groundwater table is less than 2 m from the ground surface in the areas of elevationroughly between 3 and 10 m above sea level. If the groundwater table is so close tothe surface, capillaric raise is possible and the surface vegetation can use groundwater.As well, points where the water table is sometimes in the zone of capillaric raise and thepoints where no capillaric raise is possible are indicated Figure 6-5 (Lahdenperä et al.2005).

57Ground surface elevation (m.a.s.l)0 1 2 3 4 5 6 7 8 9 10 11-10Ground surface1Thicknessof 2drytoplayer 3(m)Bottom of the zone of capillaric raise456Figure 6-5. The unsaturated top layer thickness (vertical axis) vs. ground surface elevation(horizontal axis) from shallow boreholes and upper parts of EP-boreholes. Eachtriple plot presents the maximum, the average and the minimum depth of water tablefrom the surface at the observation point. The blue triple plot indicates the water tableto be in the zone of capillaric raise (less than 2m), green ones indicate that the watertable is sometimes in the zone of capillaric raise and the grey triple plot indicates thatno capillaric raise is possible. The red dots indicate that the water table is near toground surface or above it. Red line indicates the ground surface (Lahdenperä et al.2005).Surface RunoffOlkiluoto Island forms a hydrological unit of its own; the surface waters flow directlyinto the sea. On the basis of topography and flow directions in ditches, the island is dividedinto several local drainage basins (catchment areas) as shown in Figure 6-6. Themain water divide splits the island into northern and southern parts. In the northern partditches and small streams form obvious routes for surface runoff, but in the southernpart the flow routes are more diffuse and less obvious, especially near the shoreline, dueto the subdued relief. Four measurement weirs have been installed in the main ditchessince the spring of 2003. There have been technical problems, resulting in only two fulltimeseries of data (Posiva 2005).

58Figure 6-6. Main drainage areas of Olkiluoto Island based on surface topography(Posiva 2005).On the basis of expert judgement, over 60% of precipitation evaporates, directly orthrough transpiration, and the rest forms direct surface runoff or runoff through nearsurface groundwater in the overburden. Only a few percent, at the most, infiltrates intothe deeper parts of the bedrock (Posiva 2003).Infiltration on constructed areas differs significantly from the natural state, and the constructionof the ONKALO and the related infrastructure, as well as several other constructionworks for the power plant, has altered the runoff and infiltration patterns anddecreased the transpiration. In addition to changing surface runoff routes by earthworks,the roads and constructed areas decrease infiltration locally, even where they are gravelled.Runoff generation, both in constructed and forested areas, including infiltrationprocesses, has been studied quite intensively in Finland lately (e.g., Koivusalo 2002,Kokkonen 2003, Kotola & Nurminen 2003, Metsäranta 2003, Jauhiainen 2004), and theeffects of such infrastructure development could be modelled in a rather detailed manner.The forest processes that affect the chemical properties of infiltrating water are discussedabove in Section 4.2. It should also be noted that on the basis of depositionmonitoring the amount of precipitation is about 34% less below a pine or spruce canopythan in open terrain. Part of the retained precipitation is taken up by the trees, eventuallyforming part of the evapotranspiration, and part of it reaches the soil later as moisture inlitterfall.

596.7 Radionuclides in SoilRadionuclide concentrations from the topsoil samples taken from the Hankkila and Luontosites near the Olkiluoto site in 1977-1980 are presented in Table 6-5 (Roivainen2005). Detailed description of radionuclide concentrations in 1984–2001 in topsoils ispresented in Ikonen (2003). Sr-90 and Cs-137 concentrations of the Flutanperä samplingsite at Olkiluoto are illustrated in Figures 6-7 and 6-8 below. Radionuclide concentrations(Bq/kgdw) in the topsoil of Flutanperä sampling site at Olkiluoto in August2001 are presented in Table 6-6. From the top, the soil is mouldering organic matter,clay, silt and sand (Ikonen 2003). Supplementary sampling for radionuclide analyses isplanned to be carried out from the sampling plots of the forest inventory, beginningfrom, at the latest, some years prior to the start of the operation of the disposal facilityin 2020.Table 6-5. Radionuclide concentrations in top soil samples taken from Hankkila andLuonto in 1977–1980 (Roivainen 2005).Sampling time Sampling Activity Bq/kg DW Notessite Sr-90 Cs-137 Pu-239,240September 1977 Hankkila 4.1 11 0.15 Sr-89 1 Bq/kgAugust, September 1978 Hankkila 4.1 10 0.3July 1979 Hankkila 4.5 12 0.2July 1979 Luonto 4.2 8.6 0.3July 1980 Hankkila 3.6 9.9 0.15July 1980 Luonto 3.4 8.4 0.17activity concentration (Bq/kg DW )0 5 10 15 200-2 cmdepth2-4 cm4-6 cmSoil, Flutanperä (FL), Sr-901984 1989 1993 1997 2001 2005Figure 6-7. Activity concentrations of Sr-90 in soil at the Flutanperä sampling site(Ikonen 2003, Haapanen 2006).

60activity concentration (Bq/kg DW )0 500 1000 1500 20000-2 cmdepth2-4 cm4-6 cmSoil, Flutanperä (FL), Cs-1371984 1989 1993 1997 2001 2005Figure 6-8. Activity concentrations of Cs-137 in soil at the Flutanperä site (Ikonen2003, Haapanen 2006).Table 6-6. Radionuclide concentrations (Bq/kgdw) in the topsoil of Flutanperä samplingsite in the old forests conservation area of Olkiluoto in August 2001 (Ikonen 2003). A'

61Common Reed-Carex-Sphagnum peat. In some places, thin Brown peat layers werefound in the bottom of other peat layers. Under the peat layers there were detritus andclay mud (around 0.3–1 m), sand, clay (around 1 m) and, finally, the bottom till layers.The total depth of cores varied from 40 cm to 1.5 m (Figure 6-9) (Leino 2001, Ikonen2002).The geochemistry of the peat samples was investigated by taking separately solid andliquid phases, which were analysed with standard methods. The main elements weredetermined from samples as well as pH, alkalinity, cation exchange capacity and totalorganic carbon. For determining the activity concentration of U-238, Cs-134 and Cs-137 a few soil and water samples were measured. More detailed description is presentedby Ikonen (2002) and Lahdenperä et al. (2005).The peat layers at the Olkiluodonjärvi area were too thin (20–50 cm) to develop distinctdistributions of the parameters analysed, even though some relations presented in theliterature could be confirmed (Ikonen 2002). The pH varied highly both in peat horizonsand mud horizon (Table 6-7). Water content, organic matter and cation exchange capacitywere, as expected, much higher in peat layers than in mud horizons. Sulphate andchloride concentrations increased significantly with depth. Other anion concentrationswere fairly low.Water-leached aluminium concentrations were fairly low both in peat and mud layers,except in the bottom of one core. Using HNO 3 leaching, the aluminium concentrationwas generally found to increase with depth. Iron concentrations followed the same pattern.Calsium, magnesium and sodium concentrations had quite large range, but generallyincreased toward the deeper horizons. Potassium concentrations were highest in toplayers when using water leach, but the trends were opposite in HNO 3 leach. Alkali andearth alkali metals are efficiently adsorbed in peat and mire deposits due to their highion-exchange capacity, which releases hydrogen ions and increases acidity.Adsorptive capacity of caesium depends on cation exchange capacity, soil and bottomsediment properties, dissolved solid matter and cations. Caesium and strontium concentrationswere clearly higher in mud layers. The quality of groundwater, pH and compositionof peat are the main factors, which affect the capability of peat to adsorb uranium.Adsorption is highest in un-oxidised bottom layers. Uranium adsorbs best when pH is5–7, while for the other metals adsorption is strongest at pH 4–6. When the organic carboncontent is high uranium is almost solely in organic matter, while when TOC is under1%, almost half of the uranium is adsorbed in Fe- and Mn-oxides (Ikonen 2002,Lahdenperä et al. 2005).Ground-penetrating radar probing was also carried out on the Olkiluodonjärvi wetlandarea in 2001. The aim was to map the thickness of peat layers and overburden and toproduce information on the degree of fracturing of the bedrock surface. However, thetill was so electrically conducting that the radar waves were unable to reach the bedrocksurface (Leino 2001).

62Table 6-7. Chemical characteristics of peat core samples WP001-WP004 at theOlkiluodonjärvi wetland. Median and range of values in parentheses (Ikonen 2002,Lahdenperä et al. 2005).Solid phase water leach, Method 206 Solid phase HNO 3 leach in micorwave, Method 503Variables Peat horizons N Mud horizons N Peat horizons N Mud horizons NpH i 5.7 (3.4-7.6) 16 4.7 (3.1-6.8) 19 16 15CEC,meq/100g64.8 (20.5-104) 16.5 (12.0-63.5)Anions, mg/kgBr

63Figure 6-9. Stratigraphy for the deepest peat test core WP001 situated in the middle ofthe Olkiluodonjärvi wetland area (according to Ikonen 2002 in Lahdenperä et al.2005).

64Table 6-8. Total concentrations (%) of carbon and nitrogen and C/N ratio by peatlayer in the 9 FEH plots located on peatland (Tamminen et al. 2007).0-10cm10-20cm20-30cmn C N C/NMin 9 31.4 1.41 16.5Median 47.1 2.11 20.3Max 52.7 2.88 34.3Min 6 41.8 1.36 17.5Median 46.5 2.21 19.6Max 52.8 2.81 35.7Min 5 42.7 2.06 16.5Median 48.2 2.53 17.9Max 54.3 2.92 25.3Table 6-9. Total concentrations (%) of carbon and nitrogen and C/N ratio by peatlayer and by dominant tree species in the 9 FEH plots located on peatland (Tamminenet al. 2007). Equal mean values are marked with the same letter (Bonferroni test).n C N C/NPine 2 50.6 1.52 33.3 a0-10cmBirch 5 45.7 2.23 20.6 bAlder 2 39.8 2.39 16.6 bPine 2 50.5 1.50 a 33.8 a10-20cm20-30cmBirch 4 45.0 2.41 b 18.7 bAlder 0Pine 2 51.3 2.10 a 24.4Birch 3 45.4 2.66 b 17.1Alder 0

657 SEA SEDIMENTSSea-bottom sediments at the offshore of Olkiluoto have been studied by acousticseismicmethods. The area of soundings covered about 150 km 2 and the interval of thesounding routes was about 300–500 m in east-west direction (Figure A-4; Rantataro2001, 2002, Posiva 2003). An additional survey in 2001 concentrated on the immediatesurroundings of Olkiluoto (Rantataro 2002). Seven different geological units wereinterpreted based on this acoustic-seismic sounding data and related calibrationsampling. Different sedimentary units deposited on Precambrian basement andsedimentary rock are illustrated in Fig. 7-1. The acoustic boundaries do not alwayscoincide with stratigraphical boundaries, thus caution should be used in interpreting thesediment stratigraphy.The sea-floor deposits present a very scattered pattern in the surroundings of theOlkiluoto Island (Figure 7-2). The most common Quaternary sediment on the Olkiluotooffshore bottom, representing about 30–40% of the total area, is till covered by postglacialclays, mainly Ancylus (Rantataro 2001). The amount of exposed bedrock orsedimentary rock areas on the sea floor is also 30–40 %.The isostatic land uplift andgeneral rise of sea-level after deglaciation has caused transgressional and regressionalphases in the area, which vary in extent according to locality (Björk 1995).Figure 7-1. Conceptualised sea-bottom sediment stratigraphy at Olkiluoto offshore(Posiva 2003).

66Figure 7-2. Marine geological map, showing the Quaternary sediments and rockbasement (Precambrian basement and sedimentary rocks) of the sea floor in theOlkiluoto area (Rantataro 2001).Figures 7-3 and 7-4 present the stratigraphy of the sea bottom sediments at twoacoustic-seismic lines to and at a distance from the Olkiluoto coast (lines in Fig. 5-4).There is a clear difference in the stratigraphy of these two profiles mainly due tosedimentation and erosion conditions.

Figure 7-3. The stratigraphy of the Profile 1 (Part of the line 11291150, according to Rantataro 2001, 2002, Lahdenperä 2006).67Figure 7-4. The stratigraphy of the Profile 2 (Part of the line 19181925, according to Rantataro 2001, 2002, Lahdenperä 2006).

68The shallow water environment surrounding Olkiluoto has a maximum depth of about30 m, but during the retreat of last Pleistocene ice sheet, about 11,000 years ago, thedepth of water was over 150 m due to lack of infilling sediments and depression ofground surface (Kotilainen & Hutri 2003).Changes in climate and geological environment have had a significant effect on localpalaeohydrogeological conditions at the Olkiluoto site. Based on earlier groundwatergeochemical studies it is clear that the Holocene history of the Baltic Sea, in particular,has a major effect on groundwater compositions at Olkiluoto. The salinity of the Baltichas changed during past ice ages and is expected to do so again in the future. (e.g.,Pitkänen et al. 1994, 1996, 1999a, b, 2004).Due to the differential land uplift, there is a marked difference in the sedimentation anderosional conditions between the southern Baltic Sea and the northern marine area(Kotilainen & Kohonen 2005). The annual accumulation rate varies due to the currents,bottom topography and primary production. The sediment accumulation rate (SAR) ornet sedimentation is an essential parameter in contamination or monitoring studies andin erosion/sedimentation budget calculations. Mattila et al. (2006) have studied anaverage bulk SAR at 69 stations and 99 cores from the Baltic Sea during the years1995–2003. SAR values varied widely; between 60– 6160 gm -2 /year. The highest SARvalues were observed in the northern part of Bothnian Sea, river estuaries and in theeastern part of the Gulf of Finland. At the Bothnian Sea, the median SAR values weretwo, three and seven times higher than at the stations of the Bothnian Bay, Gulf ofFinland and Baltic Proper, respectively. Near Olkiluoto basin SAR value 1810g/m 2 /year was estimated. More exact data on sedimentation rates near the offshore ofOlkiluoto are lacking.In the Baltic Sea, the sedimentary environment has changed from detrital rich sedimentsin the past to more organic rich sediments in the recent time partly due to the increasedeutrophication, which also influence the distribution of nutrients and toxic substances inthe sediments (Schernewski & Wielgat 2004).It was not possible to investigate the structure of the Precambrian rock basement at theOlkiluoto area with the acoustic-seismic equipment because of poor penetration of thesound waves into unbroken bedrock. The sound pulse could penetrate some distanceinto a more porous and soft sedimentary unit near Olkiluoto (Rantataro 2002). Thesedimentary rock areas are generally large and are situated in basement depressions andare thus sheltered from erosive forces (Paulamäki & Kuivamäki 2006). During theinterpretation of acoustic-seismic sounding data, it was found that area covered bysedimentary rock was 5–6 km from Olkiluoto (Rantataro 2002, Kuivamäki 2001), muchnearer than previously estimated. Based on this interpretation of data, the sedimentaryrock area mainly covers depressions west of the Olkiluoto Island. The topography ofrock surface varies gently in the areas that are interpreted to be covered by sedimentaryrock (Rantataro 2002).

698 TERRESTRIAL ECOSYSTEMS8.1 Terrestrial Vegetation8.1.1 Habitats and SpeciesThe main island of Olkiluoto has now been covered with intensive inventoriesconcerning the terrestrial vegetation (Fig. A-2). The extent of the vegetation study area,613.2 ha in size, and its dominant vegetation by vegetation compartments in 2002(Miettinen & Haapanen 2002) is shown in Fig. 8-1.ForestsThe 569 ha of forests within the vegetation inventory area have been inventoried bycompartments in 2003 (Rautio et al. 2004) and by 551 FET-plots in 2004 (Saramäki &Korhonen 2005).According to Saramäki & Korhonen (2005) the forests in Olkiluoto are growing onslightly more fertile sites than in Southwest Finland (Fig. 8-2). The tree speciesdistribution of forests differs from that of Southwest Finland Forestry Centre (Fig. 8-3).This is due mainly to two facts: the higher fertility of the soils and the great proportionof coastal line.0 500 1 000 MetresDominant vegetationRock vegetationPine dominatedSpruce dominatedConiferous dominatedDeciduous dominatedMixed species forestsMiresShore vegetationFigure 8-1. Vegetation on Olkiluoto in 2002 (Miettinen & Haapanen 2002).

706050OlkiluotoSouthwest Finland Forestry CentreForest site type, % of area403020100Grove andcorresp.peatlandGrove-likemineral soiland corresp.peatl.Freshmineral soiland corresp.peatl.Dryishmineral soiland corresp.peatl.Dry mineralsoil andcorresp.peatl.Extremelyinfertilemineral soiland corresp.peatl.Rocky soil,fine sandysoil, stonysoilFigure 8-2. Distribution of forest, scrub and wasteland into forest site types in 2004(based on FET plots, Saramäki & Korhonen 2005).There is a greater amount of Norway spruce (Picea abies; 44% of growing stockvolume) and deciduous species in Olkiluoto than in Southwest Finland. In Olkiluoto theproportion of silver birch (Betula pendula) and downy birch (B. pubescens) is over22%, while other deciduous trees (mainly black alder, Alnus glutinosa) account for over8%. Black alder typically forms a belt right behind the treeless shore vegetation zones.The proportion of Scots pine (Pinus sylvestris) dominated forests (32% of forest andscrub land area) is lower than in Southwest Finland. However, due to planting of pineduring last decades, pine dominates 44% of forests under 40 years of age in Olkiluoto.There is a large relatively untreated area of mature spruce forest, the Liiklanperä area,which was first conserved as old growth forest (following Act 1115/93) and later joinedto Natura network. (Saramäki & Korhonen 2005).

7170% of forest and scrub land area6050403020OlkiluotoSouthwest Finland Forestry Centre100TreelessPineSpruceSilver birchDowny birchAspenGrey alderBlack alderSallowLarchOakFigure 8-3. Dominance of tree species on forest and scrub land (FET plots in 2004,Saramäki & Korhonen 2005).According to Saramäki and Korhonen (2005), the forests of Olkiluoto are on averageyounger than in Southwest Finland (Fig. 8-4). In Southwest Finland one third of forestswere less than 40 years old, while the corresponding figure for Olkiluoto was close totwo thirds. Forests of over 120 years of age were nearly missing from Olkiluoto (Fig. 8-5). The mean volumes of different age classes were rather similar in Olkiluoto and inSouthwest Finland. The mean volumes in oldest age classes were, however, greater inOlkiluoto due to the fact that these forests consisted of mature spruces in the natureconservation area. Mean ages of forest compartments by Rautio et al. (2004) are shownin Fig. 8-5. It must be noticed that these are averages for the whole compartment, thusthe oldest age classes in the plot by plot study of Saramäki & Korhonen (2005) arebeing smoothed.

723530OlkiluotoSouthwest Finland Forestry Centre% of forest land area2520151050Treeless1-2021-4041-6061-8081-100101-120121-140141-160Over 160Figure 8-4. Distribution of forests to age classes in Olkiluoto and Southwest FinlandForestry Centre (Saramäki & Korhonen 2005).The average volume of growing stock on forest land at Olkiluoto was 104 m 3 /ha in thestudy by Rautio et al. (2004) and 112 m 3 /ha in the study by Saramäki & Korhonen(2005), and the average growth rate in 2003 was 6.3 m 3 /ha/a (Rautio et al. 2004). Thevolume is less than the average for Southwest Finland. During the past decade, therehad been cleanings of seedling stands and cuttings in 45% of the forest area of Olkiluoto(Saramäki & Korhonen 2005). The lower volume is caused by the younger age offorests and the larger amount of shoreline forests with low productivity. However, thelarge relative proportion of young forests growing rapidly keep the growth rate higherthan in Southwest Finland. Norway spruce is responsible for most of the volume andincrement of growing stock followed by Scots pine and silver birch. The greatest volumesper hectare were in the compartments belonging to the Natura area. Figure 8-6shows the mean volumes by forest compartments.

73Figure 8-5. Age classes (years) by compartments in 2003 (Rautio et al. 2004).Figure 8-6. Mean volumes (m 3 /ha) by compartments in 2003 (Rautio et al. 2004).

74The ground-, field- and shrub-layer vegetation was inventoried in 2005 by Huhta &Korpela (2006). Majority of the conifer tree stands represents various succession stagesof Myrtillus-, Vaccinium-Myrtillus-, and Deschampsia-Myrtillus-dominated spruceforests. Pine-dominated forests on rock surfaces represent Cladina-, Calluna-Cladina,and Empetrum-Vaccinium vitis-idaea/Vaccinium Myrtillus types, thus differing clearlyfrom other conifer tree stands. Deciduous forests were commonly characterised by tallgrasses notably Calamagrostis epigejos, C. purpurea and Deschampsia flexuosa. Thefield layer of deciduous forests dominated by black alder consisted of Deschampsiacespitosa, Dryopteris carthusiana, Filipendula ulmaria, Mainthemum bifolium, Oxalisacetosella, Melampyrum sylvaticum, Galium palustre, Rubus saxatilis, R. idaeus andTrientalis europaea. Spruce forests contained more species than other habitats, butdeciduous forests had highest average number of species per the 1 m 2 quadratsemployed in the study (Table 8-1).The vegetation coverage of two different forest habitats has been monitored species byspecies on the two FIP plots annually in 2003–2005. Results show that the speciesoccurrence in the understorey vegetation has remained relatively stable during this time.The variation in the number of observed species is partly due to the sporadic and scarceoccurrence of many species, which makes it difficult to detect them every year. Thecover percentages of the vegetation layers are presented in Fig. 8-7. The early inventorytime explained the lowered cover percentage of many vascular plants in 2004. Thebrowsing of elks and the carrying out of other studies in the study area has also had animpact. Forest road construction in the vicinity of FIP4 has affected the illumination andmoisture conditions. There were no statistically significant differences in the total coverpercentage of the field layer species between the first (2003) and last (2005) monitoringyears. The number of bryophyte species decreased slightly, whereas the total coverpercentage of bryophytes increased. Two rare bryophyte species, Plagiotheciumlatebricola and Jamisionella autumnalis, both classified as vulnerable, were found onFIP10. (Haapanen 2006).Table 8-1. Number of species in the forest types. Subscript indicates the standard errorof the mean. Data by Huhta & Korpela (2006).SpruceforestsPineforestsDeciduousforestsAlderforestsMiresNumber of quadrats 456 104 80 56 56Tree saplings & bushes 15 9 12 13 7Dwarf shrubs 9 9 5 2 6Herbs 65 33 43 53 23Grasses & sedges 22 19 23 27 13Field layer total 96 61 71 82 42Total number of vascular species 111 70 83 95 49Bryophytes 54 43 25 24 42Lichens 9 25 1 1 1Ground layer total 63 68 26 25 43Average no. of vascular species /quadrat 6.7 0.14 5.8 0.49 8.8 0.41 8.1 0.42 4.6 0.36Total 174 138 109 120 92

758070Cover %6050403020FIP4: Shrub layerFIP4: Field layerFIP4: Bottom layerFIP10: Shrub layerFIP10: Field layerFIP10: Bottom layer1002003 2004 2005Figure 8-7. Cover percentages of shrub, field and bottom layers in FIP4 and FIP10 in2003-2005.MiresThe relative area of mires in Olkiluoto is less than in Southwest Finland on average(Saramäki & Korhonen 2005). Since the area have been under active management, theproportion of undrained mires is lower than in Southwest Finland (Saramäki &Korhonen 2005). The peat layers are shallow (Tamminen et al. 2007), the hydrologicalconditions of drained mires are still changing, and the mires are small, which makes theestimation of mire coverage difficult. Estimates range from 4% (Rautio et al. 2004) to15% (Saramäki & Korhonen) of forest, scrub and waste land area. Despite the smallamount of mires, the range of mire types is wide, and there are both forested andtreeless mires, as well as seashore swamps (Miettinen & Haapanen 2002). Eutrophictreeless reed-rush or sedge herb swamps are common on the island. Close to theseashore these swamps, which are usually small in area, have originally been coves cutoff from the sea by land uplift. Olkiluodonjärvi is the widest reed-rush swamp in theinland area. (Miettinen & Haapanen 2002). The mires are the least species rich habitatsin Olkiluoto (Table 8-1 above). Typical species for mires were, for example,Calamagrostis purpurea, Calla palustris, Equisetum sylvaticum and above all whitemosses (Sphagnum spp.; Huhta & Korpela 2006).ShoresShore meadows appear throughout the whole coastal area of the Baltic Sea and arecommon in Olkiluoto as well. The shore vegetation is presented in Miettinen & Haapanen(2002). In the typically hydrolittoral reed, spike rush, and club rush meadows,Bolboschoenus maritimus, Schoenoplectus tabernaemontani, and especially Phragmitesaustralis (common reed) colonies grow in large monocultures throughout the studyarea. Wide reed-rush swamps are also common. Low shore meadows with rush, grasses,and sedges are usually situated in the zone between the black alder groves and coloniesof common reed. On narrow, rocky shores, the type is missing or some individuals canbe found between the rocks. Eleocharis uniglumis - Agrostis stolonifera and Juncusgerardii - Festuca rubra - Carex glareosa colonies are most common in the study area.

76Sedges are also common, but where they dominate, the shores resemble swamps.Meadowsweet (Filipendula ulmaria) colonies are the most common type of high meadows.As well, colonies of Festuca arundinacea are common, and Phalaris arundinaceais typical on rocky shores primarily in the northern parts of the island. In Tyrniemi, themain species in high meadows is often Elymus repens. In several spots Hippophaërhamnoides is growing among meadowsweet. Meadowsweet also grows in the blackalder groves next to the shore meadows.Agricultural FieldsAgricultural fields cover only 2.3% of the Olkiluoto main island, and 5.6% of wholeOlkiluoto. They are part of man-made environment and can prevail only under constanthuman management. Humans cause also a faster cycling of nutrients compared withforests via annual fertilization, scarification of soil and collection of crops. Typically,the most fertile soils with less stones and boulders are converted for agricultural use,and some soil types cannot be used at all. As stated in Chapter 2, the main line ofproduction of the farms in Eurajoki is cultivation. In the Satakunta province, 54% ofagricultural area is utilised for feed grain production, followed by grasslands under 5years (14%), other crops such as sugar beet, potato and turnip rape (13%), fallow (10%)and bread grain (8%) (Farm register 2005).Power LinesThe power line from the nuclear power production area stretches across the island beingtypically 100 m wide. The vegetation is kept low by regular management, and the areasupports bushes like Juniperus communis, bush-like birches, and pine and sprucesaplings. The ground vegetation is grassy and rich in herbs and shrubs (Miettinen &Haapanen 2002).8.1.2 BiodiversityThe significant areas of natural vegetation are the Liiklanperä old spruce forest area, theUlkopää-Tyrniemi area, with its luxuriant forests and undisturbed shoreline, and theshore vegetation in general. There is frequently a sharp boundary between these naturalhabitats and the almost urban-like surroundings of the western and middle parts of theisland. No populations of nationally endangered plant species have been found in theisland, but some locally or otherwise notable vascular plant species have been detected.The vegetation on Olkiluoto Island is relatively diverse due to the wide range ofhabitats within such a small area (Huhta & Korpela 2006). Except the rocky Scots pinehabitats, most of the Scots pine stands have been planted and thinned. In spite of themonotonous appearance of the planted pine stands, the composition of the understoreyspecies is relatively diverse as a result of the different forest succession stages. Most ofthe spruce forests have also been commercially managed, except for old-growth spruceforests in the Natura area. Most of the mires have been drained. The sea shore alderstands and the Hippophaë rhamnoides shrub zone have a diverse field layer that isespecially rich in herb and grass species.

77Table 8-2. The incidence of key tree species on forest and scrub land in Olkiluoto andSouthwest Finland in 2004 (Saramäki & Korhonen 2005). DBH denotes diameter atbreast height.Tree species and Southwest Finland Olkiluotominimum DBH stems/ha 1000 stems % stems/ha 1000 stems %Aspen >30 cm 0.48 516 7.1 0.1 0 0.2Grey alder >20 cm 0.19 205 2.8 0 0 0.0Black alder >10 cm 3.51 3735 51.1 43.8 23.5 90.5Rowan >10 cm 0.69 736 10.1 1.1 0.6 2.3Sallow >10 cm 1.15 1219 16.7 3.4 1.8 7.0Mountain elm >5 cm 0.02 17 0.2 0 0 0.0Linden 0.04 40 0.5 0 0 0.0Oak > 5 cm 0.72 768 10.5 0 0 0.0Maple >5 cm 0.07 73 1.0 0 0 0.0Total 6.87 7309 100.0 48.4 25.9 100.0The distribution of dead wood in Olkiluoto is patchy and mostly found in theLiiklanperä area (Saramäki & Korhonen 2005). Since the nature conservation area isdominated by spruce, the proportion of spruce in dead wood is also higher than onaverage for Southwest Finland. Consequently the proportion of dead pine wood is low.Deciduous trees are well represented in dead wood in Olkiluoto. The mean volume ofdead wood in Olkiluoto is 6.24 m 3 /ha (in Southwest Finland 1.82 m 3 /ha). The number ofblack alder is high in Olkiluoto due to the long shoreline (Table 8-2). However, thereare only a few big aspens in Olkiluoto and elm, linden, oak, and maple were not foundon the forest inventory area. However, Huhta & Korpela (2006) found maple thicketsoutside the FET plot network, at the shoreline.8.1.3 Nutrient ConcentrationsIn 2005 and 2006, nutrient analyses were carried out on the ground vegetation and treefoliage of the 94 FEH plots to map the current nutrient status of forest vegetation onOlkiluoto Island. When possible, shoot samples of the most abundant or frequentevergreen and deciduous dwarf shrub, herb, grass, bryophyte and lichen species werecollected from each plot for chemical analysis (Huhta & Korpela 2006). Leaf samplesof trees were collected for chemical analysis in August 2005, and needle samples inMarch 2006 (Tamminen et al. 2007). Samples were taken individually from thedominant tree species on each plot. When possible, remaining part of the samples werearchived for future use.The carbon and nitrogen concentrations of the samples were analysed with a CHNanalyser. The element concentrations (P, K, S, Ca, Mg, B, Cu, Zn, Mn, Na, Fe, Al, Cd,Cr, Ni, Pb and Mo) were determined by wet digestion (HNO 3 /H 2 O 2 ) and analysed byICP-AES. The results were expressed as concentration per weight of dry matter (dryingat +105°C). Concentrations of exchangeable cations, pH and exchangeable acidity werealso determined and cation exchange capacity and base saturation calculated from thesoil samples.

78The mean carbon content in vegetation groups varied between 47% and 52%(Tamminen et al. 2007). The concentrations of the macronutrients were higher invascular plants than in bryophytes and lichens. Lichens had always lowerconcentrations than bryophytes. Macronutrient concentrations in vascular species wererelatively similar to the concentrations measured in southern Finland (Mäkipää 1994,Salemaa et al. 2004). Compared with the nationwide bryophyte data (Poikolainen et al.1998) the N % of Hylocomium splendens (0.97–1.41%) and Pleurozium schreberi(0.92–1.26%) at Olkiluoto represented well the range observed in southern Finland in1995 (Fig. 8-8).Boron concentrations were high in dwarf shrubs and herbs, but low in grasses,bryophytes and lichens. In general, vascular plants had lower heavy metalconcentrations than bryophytes. Bryophytes accumulated especially Cu, Ni and Fe. TheFe concentrations of bryophytes and lichens at Olkiluoto were as high as near theHarjavalta Cu-Ni smelter at the distance of 4–8 km in the beginning of 1990s (Salemaaet al. 2004). It is obvious that the particulate and dust accumulation on vegetation,especially on forest floor bryophytes, has been increased due to emissions caused bysoil construction and industrial activities on Olkiluoto Island. Al, Cd and Crconcentrations were also high in bryophytes and Pb concentrations were higher than thedetection level for analysis only in bryophytes and lichens.Nitrogen (N) in plants32.5%21.51EvergreenVacc myrtHerbsGrassesMossesLichens0.50c ab a b c bc a a b c a a b bc c a a bc b c a a aOMT+ MT VT - ClT Rocks Alder Birch PineUpland sitesPeatland sitesFigure 8-8. The site type specific mean N concentrations of different plant groups(Tamminen et al. 2007). See Table 6-1 for definition of forest site types. OMT+ includesone grove (Lh) stand in addition to the herb rich heaths. Equal mean values are markedwith the same letter (Least Significant Difference Test).

79Foliage analyses indicated mainly good nutritional status of studied forests on theOlkiluoto Island (Fig. 8-9, Tamminen et al. 2007). However, calcium concentration inScots pine needles, sulphur and copper in Norway spruce needles and phosphorus, potassiumand copper concentrations in birch leaves were below optimal values. Averagecarbon content was 52.8% in current needles of pine and 51.4 in spruce. Birch and aldergrowing on peatland sites have slightly higher carbon content in their leaves (53.2% forbirch and 51.9% for alder) than trees growing on mineral soils (52.5% and 51.8%, respectively).Figure 8-9. Needle nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium(Ca) and magnesium (Mg) concentrations (+standard error) in current (C) andprevious-year (C+1) needles of Scots pine and Norway spruce stands grouped by sitefertility and stand age (Tamminen et al. 2007). See Table 6-1 for definition of forest sitetypes. Here MT includes also site types less fertile than MT, and OMT also site typesmore fertile than OMT.

808.1.4 RadionuclidesTable 8-3 shows some examples of radionuclides and their activities detected interrestrial environment in the monitoring program of the nuclear power plant in 2004and 2005. Cs-137, originating from Chernobyl fallout, was the dominating radionuclide.In addition to it and the natural Be-7 and K-40, of the long-lived nuclides, Sr-90 and Cs-134 (from Chernobyl as well) were detected. For more data, readers are referred tosummary reports by Ikonen (2003), Roivainen (2005), and Haapanen (2005, 2006).Table 8-3. Radionuclides in terrestrial environment in the vicinity of the weather mastin 2004–2005, Bq/kgDW (Haapanen 2005, 2006).Type Be-7 ±% K-40 ±% Cs-134 ±% Cs-137 ±%Pine needles 2005 44 6 106 6 - 92 5Pine needles 2004 35 7 107 5 0.37 20 207 4Lichen 2005 154 5 39 5 0.44 12 273 5Lichen 2004 163 5 44 7 0.77 9 510 5Roivainen (2006) studied the distribution of some radionuclides (K-40, Cs-137, Cs-134and Be-7) and stable elements (K, P, Ca and Cu) in three shoreline alder forests ofOlkiluoto. Samples were collected from vegetation and small mammals. Be-7 wasfound in litter and understorey samples only. It was found that the behaviour of theelements did not differ from what is generally known from their behaviour in forests.Clear differences were found between the monitoring plots in the distribution of theelements on the basis of concentration ratios.8.1.5 Estimates for the Larger AreaInformation of the structure of the forests within the larger study area was obtainedfrom Multi-Source National Forest Inventory (MS-NFI) GIS layers. Figure 8-10presents the average volumes in 2006 (results from NFI10). Olkiluoto deviates fromother coastal regions, peninsulas and islands due to its heavier infrastructure and thepractised intensive forest management. In general, it is more similar to the mainland.The mean volume estimate derived for the main island of Olkiluoto was 121 m 3 /ha andthat for the larger study area 134 m 3 /ha. This estimate for Olkiluoto is higher than thefield inventory-based results for forest, scrub and waste land by Rautio et al. (2004; 100m 3 /ha) and Saramäki & Korhonen (2005; 110 m 3 /ha). This is probably due to the factthat the seashore pixels get some reflectance of the water and get artificially highvolume-estimates. However, the difference between the larger study area (which alsocontains a large amount of mixed shoreline pixels), and Olkiluoto is clear based onthese values as well. Forests on main island of Olkiluoto are slightly younger andcontain a larger proportion of deciduous trees (Table 8-4). Both conditions contribute tothe lower volume.In Fig. 8-11 the MS-NFI mean volume maps from NFI8 (1994) and NFI9 (1999) aregiven. Between 1994 and 2006, the infrastructure growth on Olkiluoto can be depicted.In the larger area, there have been clear-cuts, but the volume has also increased in areasthat have been left untreated.

81Figure 8-10. Volume of growing stock according to the 10th National Forest Inventory.Data by Finnish Forest Research Institute.Table 8-4. Comparison of forest characteristics of Olkiluoto main island and largerstudy area based on multi-source inventory results (10th National Forest Inventory byFinnish Forest Research Institute).Olkiluoto Larger study areaMean age of forests, years 53 57Mean volume of growing stock, m 3 /ha 121 134Deciduous species, % of growing stock volume 24 20Site types equal or better than MT (fresh mineral soil type and 79 78corresponding peatland), % of forest area

82Figure 8-11. Volume of growing stock according to the 8th and 9th National ForestInventories. Data by Finnish Forest Research Institute.

838.2 Terrestrial Wildlife8.2.1 Wildlife on Olkiluoto IslandThe wildlife surveys made in Olkiluoto conclude that the community composition andspecies richness inside the island do not deviate from the surrounding districts. Thecommercial forestry is the single most significant factor affecting the current wildlife inOlkiluoto, as well as elsewhere in the forested areas of southern Finland.Birdlife in Olkiluoto has been surveyed by Yrjölä (1997). Regarding land birds,Olkiluoto Island is a typical representative of Finnish southern coast forest areas; eventhough the number of species is high, the area is not important for the occurrence of rarespecies. In terms of waterfowl, however, the island is more valuable as some scarce ornationally decreasing species, such as shelduck (Tadorna tadorna), velvet scoter(Melanitta fusca) and scaup (Aythya marila), were observed. As well, the overallnumber of breeding waterfowl in the area was high. The northern seashore of the islandturned out to be the most valuable as waterfowl habitat. Yrjölä (1997) observed that thebirdlife in areas with the strongest human impact had a lower conservation value whencompared with the birdlife in the shoreline habitats and the old-growth forest area in thesouthern side of the island.Given the size of Olkiluoto Island and the length of shoreline the annual hunting bag isso small that the hunting mortality does not have any significant effect on game birdpopulations on the island. Regarding migratory birds it is, of course, possible that highmortality elsewhere can affect population viability also in Olkiluoto.The mammalian fauna on the island is very typical to coastal areas in Southwest Finland(Ikonen et al. 2003, Ranta et al. 2005, Oja & Oja 2006). The results of interviews oflocal hunters concerning game animals are presented in Table 8-5. In addition, bat andsmall mammal populations on the island have been studied in 2004 (Ranta et al 2005).Three species of bats and three species of small mammals were found in this case study,and the observed individuals represented the most common species in the country. Nosigns of the occurrence of endangered or threatened species have been found. Inaddition to the mentioned studies, Siitonen & Ranta (1997) provided observational dataon mammals. In spite of the availability of suitable habitat, there was no evidence onthe occurrence of the endangered flying squirrel.Unlike birds, there are some mammal species on the island whose populations areregulated mainly by hunting. The population estimates of moose and white-tailed deerare probably fairly accurate, and it seems that some 30–50% of their population isharvested annually (Oja & Oja 2006). As well, raccoon dogs are killed in fairly largenumbers, but the reproductive potential of the species is higher than in the case ofcervids.The only research on invertebrates in Olkiluoto is carried out by Ranta et al. (2005).The study was on Carabids, and the observed Carabid species were among the mostcommon in Finland, and typical to the examined habitats (Ranta et al. 2005).

84Table 8-5. Game catches (number of individuals) at Olkiluoto in 2002–2005. Tableaccording to Oja & Oja (2006), population estimates partly based on earlier estimates,summarised in Haapanen (2005). Missing information is marked with -. In populationestimates * denotes situation before hunting season.Species 2002 2003 2004 2005 PopulationAmerican Mink (Mustela vison) 2 8 - 9 >15Badger (Meles meles) 0 1 0 0 one pair?Brown hare (Lepus europaeus) 0 1 0 2 10-15Moose (Alces alces) 10 - 5 7 16*Mountain hare (Lepus timidus) 3 2 0 2 20-25Muskrat (Ondatra zibethicus) 0 0 0 0 0Pine marten (Martes martes) 0 0 0 0 one pair?Raccoon dog (Nyctereutes 12 19 10 9 >20procyonoides)Red fox (Vulpes vulpes) 1 7 - 1 >20Red squirrel (Sciurus vulgaris) 0 0 0 0 60-100Roe deer (Capreolus capreolus) 0 1 0 5-10 15-20White-tailed deer (Odocoileus - - 5 10 20*virginianus)Black grouse (Tetrao tetrix) - - 1 0Hazel grouse (Bonasa bonasia) - - 5 0Hooded crow (Corvus corone) - - 2 2Mallard (Anas platyrhynchos) - - 18 5Teal (Anas crecca) - - 4 0Woodcock (Scolopax rusticola) - - 2 08.2.2 Power Production Infrastructure and Terrestrial WildlifeThe nuclear power production and related activities on Olkiluoto Island have variousimpacts on local wildlife. Some of these effects are hard to mitigate or cannot beavoided at the current circumstances. These include, for example, habitat loss andconversion, disturbance by industrial noise, disturbance and increased mortality bytraffic as well as the adverse effects of man-made edges in forest environments. Someeffects, like habitat fragmentation, dispersal barriers and increased avian mortality bypower lines and tall buildings, are either insignificant or they can be managed withproper mitigation measures. The only actual large-scale wildlife effect that ischaracteristic particularly to the large-scale power production is the impact of thethermal effluent from the power plant.Although the main scope of this report is to describe the biosphere at Olkiluoto as it is,for better understanding of the fauna populations it is also worth considering theimpacts of the human activities more than in the other sectors covered in this report.The focus is not to make an environmental impact evaluation of the activities, but tocollect the available information to support interpretations of site data and itsapplication further in the biosphere assessment.Habitat Loss and Habitat ConversionOf the total area of Olkiluoto Island, some 19% is used for nuclear power productionand the related activities (see Table 2-1 in Chapter 2). On a local scale, this proportion

85is high, but in relation to other land use on a regional scale its role is insignificant. Assumingthat the conservation value of lost habitats has not been particularly high andthey have represented typical commercial forests and seashore habitats, the habitat lossdue to power production in Olkiluoto has only produced a proportional decline in thenumber of animals living in that particular landscape. This is in accordance with therandom sample hypothesis, which states that small patches are simply random samplesof larger patches (Haila 1983).In addition to the habitat that is lost in the construction of industrial complexes on theOlkiluoto Island, there are certain habitat conversions where an ‘artificial’ habitat isoccupied by a largely different wildlife community than before the power production.The most important are the 10 hectare Korvensuo water reservoir and the semi-openhabitat of the power-line corridors. A few muskrats have been seen in the reservoir(Ikonen et al. 2003), even though muskrat has decreased dramatically in the wholecountry during the last decade. The power line corridors dominated by tall grasses andbush thickets cover 5.6% of the main island of Olkiluoto. This habitat type enables theoccurrence of certain bird and mammal species as well as some invertebrates that favouropen and semi-open habitats.Habitat Fragmentation and Wildlife Dispersal BarriersConstruction of power production infrastructure splits habitat patches. Power-linecorridors and roads act as dispersal barriers for certain terrestrial animals. This is foundto be true for example in the case of small mammals. Surprisingly, the avoidancebehaviour toward power lines is sometimes found also in much larger mammals. Insouthern Norway, power lines, particularly in combination with roads, maysubstantially affect the distribution of wild reindeer (Nelleman et al. 2001, Vistnes et al.2004).Habitat fragmentation by power lines and roads, or the role of these linear structures asdispersal barriers does not have any significant role in Olkiluoto. In theory, roads andpower-line corridors could contribute to the fragmentation of the habitat of many forestinvertebrates also in boreal forest environment, but that would require severalpreconditions. The species in question should be habitat specialist. As well, its dispersalability should be poor, so that it is not able to cross a road or a corridor. The specifichabitat of that species should occur in such a small patches that if a road or power-linecorridor would split a patch into two, either of those smaller habitat patches could notsupport a viable population. Most probably this is not the case in the commercial forestsof Olkiluoto, and the natural or nearly natural habitats with some conservation valuegenerally occur as continuous patches.Power-line Mortality of WildlifeA more significant impact of power lines and roads on animals is that they commonlyincrease the mortality rate in population. Collisions with power lines and electrocutionappear to be a source of systematic mortality for many species of birds in boreal forestenvironment (Bevanger 1994, 1995a, 1995b). Koistinen (2004) calculated that inFinland, the power-line collisions kill approximately 200,000 birds per year. This means

86an average of 0.7 collisions per year and per one kilometre of power line. Using theaverage estimate given by Koistinen (2004) the minimum annual number of lethalpower-line collisions on the island is around seven individuals. However, he stressesthat the collision probabilities increase greatly in the vicinity of wetland habitats, especiallyduring migration, as the avian densities are high. Therefore it is probable that theactual number of power-line collision victims on the island is somewhat greater.Road MortalityDepending on the calculation methodology, annually 15–30 small and medium-sizedvertebrates are killed per one road kilometre, when forestry roads are excluded(Manneri 2002). The roads of Olkiluoto and their traffic density suggest that the annualnumber of vertebrates killed on roads on the island is probably 75–150 individuals.Man-made EdgesConstruction of power plant and related infrastructure creates permanent openings inpreviously closed forest environments. However, commercial forestry also in itselftypically produces sharp edges into forests. The increasing openness and sharp anddistinct man-made edges also affect the micro-climatic conditions in the untouchedareas in the immediate surroundings. The surroundings are exposed to more intensivesunlight and heavier winds than before. During the growing season, this increases theaverage temperatures and decreases the humidity. These changes have permanenteffects on the plant community along the newly established edge, and subsequently alsomodifies the local animal community, particularly that of invertebrates and birds. It hasbeen evaluated that, in the boreal forest environment, the horizontal coverage of thiskind of micro-climatic edge effect reaches approximately three times the height of thecanopy into the neighbouring untouched forest (Harris 1984). In narrow strips of openland, such as roads and power-line corridors, the coverage of the effect is presumablysmaller.Many of the rare and threatened forest invertebrates dependent on dead wood aresensitive to microclimatic changes caused by the mentioned edge effect. There might bea certain potential for preservation of these species in Olkiluoto.Disturbance by Traffic and NoiseNoise may decrease avian density and breeding success (Henson & Grant 1991, Reijnen& Foppen 1994, Reijnen et al. 1995, 1996, 1997). Van der Zande et al. (1980) statedthat road traffic reduced the densities of the lapwing (Vanellus vanellus) and blacktailedgodwit (Limosa limosa) up to two kilometres away from the road in open fieldhabitats. Waders seem to be particularly sensitive also according to Reijnen et al. (1997)and Hirvonen (2001), who studied the effects of the construction of a two lane highwayin Finland. In the zone where traffic noise was > 56 dB the number of breeding wadersdeclined, whereas in areas where traffic noise was < 56 dB wader abundance remainedfairly constant. In the case of Olkiluoto it has been estimated that during the constructionof the repository, noise will disturb nesting birds within a maximum range of onekilometre (Posiva 2003). In a forested environment the range of disturbance is estimated

87to be in 100–300 meter class. Referring to the above literature, it seems probable thatthe disturbing effect of the construction noise is more severe.Wildlife Effects of the Thermal EffluentsIn the cooling water discharge area of a power plant, the average temperature is higherthan natural. This thermal effluent from power-plant cooling supports waterfowl andwading birds (Brisbin & Vargo 1982, Haymes & Sheehan 1982, Esler 1992, Bildstein etal. 1994). Some studies suggest that cooling sites attract piscivores, and, among themespecially herons, cormorants and goosanders (Esler 1992, Sandström 1986).The thermal effluent affects local birdlife particularly in the winter as the open watersdraw together flocks of waterfowl that may contain thousands of birds. According to abird watcher familiar with Olkiluoto site, Ville Vasko, the most numerous winteringspecies are goosander (Mergus merganser), goldeneye (Bucephala glangula), mallard(Anas platyrhynchos) and mute swan (Cygnus olor). During the coldest months, thehighest number per day of these four species have been 1300, 1000, 400 and 275,respectively. Practically all of them would spend the winters elsewhere without thenuclear power plant. As the sea ice starts to melt in April, other species also start togather in large numbers. In total 800 tufted ducks and 700 coots (Fulica atra) have beenobserved in one day. Altogether more than twenty species of waterfowl and seabirdshave wintered on the site. The data is from Ville Vasko's statistics, covering the last fiveyears.

899 SEA ECOSYSTEMSThe state of the waters near the Olkiluoto nuclear power station, on the southwest coastof Finland, and the effects of its cooling water on the water quality and biologicalproduction of the surrounding sea area have been the subject of statutory monitoringsince 1979 (Turkki 2006). In addition to the cooling water, other factors affecting thewater quality and biological production in the Olkiluoto area are the general state of thecoastal waters of the Bothnian Sea, the nutrients carried from the mainland by the riversEurajoki and Lapinjoki and the local wastewater load.The Olkiluoto sea area comprises a moderately open and shallow sea area with anaverage depth of less than 10 metres. Due to the paucity of islands, the flow conditionsare strongly affected by winds. The cooling water from the nuclear power plantsincreases the temperature of the sea water and thereby also changes the flow conditions.Teollisuuden Voima Oy’s two nuclear power plants take their cooling water from theOlkiluodonvesi area and discharge them in the sea area off Kaalonperä. The powerplants consume a total of 5.2 million m 3 /d of cooling water, which is six times the meanflow of the river Eurajoki. Nowadays, the temperature of the cooling water rises bysome 13.6 degrees in the cooling system (Kirkkala & Turkki 2005, Turkki 2006).In the following, a division into the future lake areas in Fig. 1-5 is employed, and thesepotential lakes are called Target areas. The observation locations (SEA points) areshown in Fig. A-3.9.1 Physico-Chemical Water QualityTemperature ConditionsThe most important environmental load in the sea caused by the Olkiluoto nuclearpower station is caused by the discharge of cooling water into the sea area off Olkiluoto(Target area 3a). This can be seen most clearly in winter as an unfrozen water area afew square kilometres in size and in changes to the ice conditions (Fig. 9-1). Thetemperature in the discharge area in the sea area off Kaalonperä is usually 5–7ºC higherin the surface layer and 1–1.5ºC higher in the deeper layers than the backgroundtemperature. The difference in the temperature between the waters in the discharge areaand near Olkiluoto and those in the open sea seems to have increased slightly during theperiod 1999–2005. The local increase in temperature is of relevance to fish, the iceconditions in the waters near Olkiluoto and the algae production in the unfrozen waterarea. During the open-water season, the temperature increase of the sea water is morelocalised. For example, during the open-water season 2005, a considerable increase intemperature (more than 3ºC) was only observed in the surface layer (0–2 m) in thedischarge area and a slight increase (1–3ºC) was observed at a distance of 3 kilometresfrom the discharge point (Turkki 2006).In the cooling water discharge area (Target area 3a/SEA08) the water is clearly stratifiedin terms of temperature, especially in late winter, when water near the bottom isclearly colder than the water in the surface layer (1–2 metres). Normally, and at other

90observation sites in the sea area off Olkiluoto, the water near the bottom is slightlywarmer than the water at the surface in late winter, or the temperature differences betweenthe water layers are very small. During the spring and autumn turnovers, the differencesin water temperature between the different layers have often been small in thesea area off Kaalonperä, too. In summer the water in the surface layers is also normallywarmer than in the layers near the bottom, but the increase in the temperature of thesurface layers is considerably higher in the sea area off Kaalonperä than in other partsof the area. The Eurajoensalmi area (Target area 1/SEA09) is quite shallow, and there ishardly any thermal stratification (Kirkkala & Turkki 2005).Oxygen LevelsThe oxygen saturation of sea water affects the nutrient concentrations in the bottomnearwaters. The oxygen level in the waters near Olkiluoto has mainly remained goodnear the bottom (Fig. 9-2). In the cooling water discharge area (Target area 3/SEA06)the oxygen level at the bottom weakened in the late 1990s and especially in the early2000s. The oxygen level was at its worst at other observation sites too after the summerof 2002. This summer was considerably warmer than normal and during it residues ofalgae and plants accumulated in the deep areas and consumed the limited oxygenresources of the water mass as they degraded (Mattila 2003). In recent years the oxygenconditions in the water near the bottom have been better than normal. The oxygen levelin the Eurajoensalmi area (Target area 1/SEA09) has been good almost withoutexception, as there is hardly any thermal stratification due to the shallowness of thearea.Temperature -5ºCUnfrozen water surface area6.4 km 2 20 cm10 cm5 cm2.5 cm0 cmFigure 9-1. The area affected by the cooling water from the Olkiluoto nuclear powerstation in a winter with normal ice conditions (based on modelling). The size of the unfrozenwater area typically ranges from 3 to 20 km 2 , depending on the harshness andthe time of winter.

91Lake1/Sea09Target area 1/SEA09Lake3/Sea05Target area 3b/SEA05Ave. Max. Min.Ave. Max. Min.1201008012010080%60%6040200402001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea06Target area 3a/SEA06Lake3/Sea08Target area 3a/SEA08Ave. Max. Min.Ave. Max. Min.1201201001008080%60%6040402020001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea07Target area 3a/SEA07Lake2/Sea03Target area 2/SEA03Ave. Max. Min.Ave. Max. Min.1201201001008080%60%6040402020001990199219941996199820002002200419901992199419961998200020022004Sea10 SEA1012010080604020019901992199419961998200020022004%Ave. Max. Min.Figure 9-2. Average, minimum and maximum values for oxygen saturation (%) near thebottom in waters near Olkiluoto during the open-water season in the years 1990–2005.

92Nutrient and Suspended Solids ConcentrationsThe nutrient and suspended solids concentrations in the water in the sea area offOlkiluoto have been typical for the coastal waters of the Bothnian Sea. There have beenrelatively minor local variations in the nitrogen and phosphorus concentrations of thesea water, although flows, nutrients released from the coastal zone and to some extentthe local wastewater load temporarily increase the concentrations in the cooling waterdischarge and intake areas (Target areas 3a and 3b). The state of the Eurajoensalmi area(Target area 1/SEA09) is mainly determined by the water brought by the river Eurajokiand the nutrients contained in this water. In winter, the surface layer of the water in thebay often consists of river water which is carried below the ice as a thin layer of turbidwater up to the mouth of the bay (Kirkkala & Turkki 2005).Total phosphorus concentrations in the production layer were increasing until the early2000s, but during the last three years (2003–2005) concentrations have decreased (Fig.9-3). With the exception of the Eurajoensalmi area (Target area 1/SEA09), this is alsoreflected in nitrogen concentrations in the water (Fig. 9-4). Even though the waterclarity (expressed as Secchi depths) has not yet reached the level of the early 1990s, ithas clearly improved in recent years (Fig. 9-6).Nitrogen and phosphorus concentrations during the open-water season have variedrelatively little in the cooling water discharge area, but have usually increased towardsthe end of summer and autumn (Fig. 9-5). In the 2000s, phosphorus concentrationsduring the open-water season reached their highest level during the warm summer of2002, while nitrogen concentrations were highest in 2001, which was preceded by anexceptionally mild winter period. In the longer-term, there has been remittent, irregularvariation in phosphorus concentrations in the sea water during the open-water season(Fig. 9-7, Table 9-1). There is a slightly increasing trend in concentrations in the entiresea area, but in recent years concentrations have decreased again.In the Eurajoensalmi area (Target area 1), phosphorus and particularly nitrogenconcentrations have often been higher in the uppermost surface layer (1 m) due to theeffect of river waters. In the intermediary layer (5 m), nitrogen concentration is mostlyslightly higher than near the bottom, while there are no clear differences in phosphorusconcentration between the intermediary layer and the layer near the bottom, if oxygenconditions are good (Figs. 9-9 and 9-10). The Olkiluodonvesi area is a shallow waterarea, and at the observation site (Target area 3b/SEA05, total depth 6.5 m), the nutrientsof the intermediary layer have not been studied. Nitrogen concentrations in the waterhave mostly been higher in the surface layer (1 m) than near the bottom, whilephosphorus concentrations are higher in the water near the bottom. In the areasouthwest of Kuusinen (Target area 3a), nitrogen concentrations in the water have oftenbeen higher in the surface layer, and phosphorus concentrations have been higher in thewater layer near the bottom, but no significant differences can be found between theother water layers.The state of the bottom in the cooling water discharge area (Target area 3a) deterioratedin the late 1990s and the early 2000s due to intermittent lack of oxygen caused by deg-

93radation of plant residues. This could also be seen in an increase in nutrient concentrationsnear the bottom (Fig. 9-8).North of Puskkari (Target area 3a) nutrient concentrations near the bottom have beenhigher than in other water layers, especially in winter, but otherwise there have not beengreat differences between the water layers. In the cooling water discharge area in thesea area off Kaalonperä (Target area 3a), nitrogen concentrations have been at the samelevel in all water layers, but phosphorus concentrations have often been clearly higherin the water near the bottom than in other water layers. Differences in phosphorusconcentrations between the 1 m- and 5 m-layers have been small. Likewise in the areaeast of Susikari (Target area 2), differences in nutrient concentrations have been smallbetween the different water layers. North-east of Pyrekari (north of Target area 2),differences in nitrogen concentrations between the water layers have been small, butgreater variation in phosphorus concentrations has been observed between the waterlayers in this area than at other observation sites.

94Target Lake1/Sea09 area 1/SEA094035302520151050µg/lLake3/Sea05Target area 3b/SEA0540µg/l353025201510501990199219941996199820002002200419901992199419961998200020022004Lake3/Sea06Target area 3a/SEA0640µg/l35302520151050Lake3/Sea08Target area 3a/SEA0840µg/l353025201510501990199219941996199820002002200419901992199419961998200020022004Target Lake3/Sea07 area 3a/SEA0740µg/l35302520151050Lake2/Sea03Target area 2/SEA0340353025201510501990199219941996199820002002200419901992199419961998200020022004µg/lSea10 SEA10403530252015105019901992199419961998200020022004µg/lFigure 9-3. Average phosphorus concentrations in the production layer in the watersnear Olkiluoto for July–August in the years 1990–2005.

95Target Lake1/Sea09 area 1/SEA09450400350300250200150100500µg/l19901992199419961998200020022004Target Lake03/Sea05area 3b/SEA05450400350300250200150100500µg/l19901992199419961998200020022004Target Lake3/Sea06 area 3a/SEA06450400350300250200150100500µg/lTarget Lake3/Sea08 area 3a/SEA084504003503002502001501005001990199219941996199820002002200419901992199419961998µg/l200020022004Target Lake3/Sea07 area 3a/SEA07450400350300250200150100500µg/lTarget Lake2/Sea03 area 2/SEA034504003503002502001501005001990199219941996µg/l199820002002200419901992199419961998200020022004SEA10 Sea10450400350300250200150100500µg/l19901992199419961998200020022004Figure 9-4. Average nitrogen concentrations in the production layer in the waters nearOlkiluoto for July–August in the years 1990–2005.

962000 2001 2002 2003 2004 200535Total phosphorusµg/l302520151050May June July August SeptemberTotal nitrogen500400µg/l3002001000May June July August SeptemberChlorophyll43µg/l210May June July August SeptemberFigure 9-5. Nutrient concentrations and phytoplankton production results for the productionlayer at the cooling water discharge point (Target area 3a/SEA08) in the openwaterseasons 2000–2005.

972000 2001 2002 2003 2004 2005350Primary production capacity300250mg C/m³.d200150100500May June July August SeptemberIn situ primary productionmg C/m².d8007006005004003002001000May June July August SeptemberPhytoplankton biomassmg/m³180016001400120010008006004002000Beginning of May June July August SeptemberFigure 9-5 cont'd. Nutrient concentrations and phytoplankton production results for theproduction layer at the cooling water discharge point (Target area 3a/SEA08) in theopen-water seasons 2000–2005.

98Lake1/Sea09Target area 1/SEA096Target Lake3/Sea05 area 3b/SEA0565544m3m32211001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea06Target area 3a/SEA066Target Lake3/Sea08 area 3a/SEA0865544m3m32211001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea07Target area 3a/SEA076Target Lake2/Sea03 area 2/SEA0365544m3m32211001990199219941996199820002002200419901992199419961998200020022004Sea10 SEA10654321019901992199419961998200020022004mFigure 9-6. Average Secchi depths in the waters near Olkiluoto for July–August in theyears 1990–2005.

.99mg/m 33025TA Lake3/Sea083a/SEA08TA Lake3/Sea073a/SEA07SEA10 Sea10201510501979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005Figure 9-7. Average phosphorus concentration (mg/m 3 , 0–10 m) at the survey pointsTarget area 3a/SEA08, Target area 3a/SEA07 and SEA10 in the waters near Olkiluotoduring the open-water seasons in the years 1979–2005.Total nitrogenTotal phosphorusLate winterLate summerLate winterLate summerµg/l50045040035030025020015010050090807060504030201001990199219941996199820002002200419901992199419961998200020022004µg/lFigure 9-8. Total nitrogen and total phosphorus concentrations in the water near thebottom at the cooling water discharge point (Target area 3a/SEA08) in late winter andlate summer in the years 1990–2005. (The sample for late winter was taken in March inthe years 1997 and 1998 and in February in other years. The sample for late summerwas taken in July in the years 1990–1998 and in August in the years 1999–2005.)

100Table 9-1. Phosphorus concentrations in the water during the open-water seasons1979–84, 1985–89, 1990–94, 1995–99, 2000, 2001, 2002, 2003, 2004 and 2005 (µg/l,standard deviation in subscript) in the Olkiluoto sea area (TA=Target area) and in referenceareas (SEA10 near Olkiluoto and Ref. 310 off Pyhäranta Tuvy/LoSYK, in 2002L-S vesi- ja ympäristötutkimus Oy).Survey point 1979- 1985- 1990- 1995- 2000 2001 2002 2003 2004 2005depth, m 1984 1989 1994 1999TA3b/SEA050–6 15 5 16 4 17 8 22 5 27 10 23 5 19 7 16 5 19 4 18 4TA3a/SEA060–10 15 4 16 4 15 4 19 5 18 4 19 5 14 2 14 2 17 7 17 412–14 15 4 17 4 17 5 23 6 23 6 30 5 43 52 17 2 20 8 21 5TA2/SEA030–10 16 7 16 9 14 5 19 5 19 3 23 12 17 4 14 2 18 8 16 411–12 17 3 15 5 19 13TA1/SEA090–8 17 8 19 14 16 6 25 9 19 3 20 6 17 4 18 5 20 7 19 412–14 13 4 14 4 14 6 16 5 20 4 15 4 13 2 15 2 12 0 11 0TA3a/SEA080–8.5 16 6 17 5 18 7 22 6 19 4 23 7 23 19 16 7 21 7 18 5TA3a/SEA070–7.5 14 5 16 5 15 5 20 6 20 5 19 5 16 4 14 2 19 8 16 5SEA100–10 12 4 14 4 14 6 16 5 15 2 15 3 13 2 14 2 12 4 10 1Ref. 3100–10 14 5 15 4 14 4 16 4 24 1 15 17 315–16 16 7 17 6 15 5 17 4 34

101TA Lake1/Sea091/SEA09450040003500300025002000150010005000µg/l1 m5 m8 m1.2.20001.6.20001.10.20001.2.20011.6.20011.10.20011.2.20021.6.20021.10.20021.2.20031.6.20031.10.20031.2.20041.6.20041.10.20041.2.20051.6.20051.10.20051.2.20061.6.2006Lake3/Sea05TA 3b/SEA05µg/l70060050040030020010001 m5.5 m16.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006TA 3a/SEA06Lake3/Sea06µg/l5004504003503002502001501005001 m5 m10 m13 m16.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006Lake3/Sea08TA 3a/SEA0850045040035030025020015010050016.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006µg/l1 m5 m8.5 mFigure 9-9. Total nitrogen concentration in different water layers in the waters nearOlkiluoto in the years 2000–2006. TA = Target area.

102Lake3/Sea07TA 3a/SEA07µg/l4504003503002502001501005001m5 m7 m16.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006TA 2/SEA03Lake2/Sea03µg/l70060050040030020010001 m5 m10 m1.2.20001.6.20001.10.20001.2.20011.6.20011.10.20011.2.20021.6.20021.10.20021.2.20031.6.20031.10.20031.2.20041.6.20041.10.20041.2.20051.6.20051.10.20051.2.20061.6.2006Sea10SEA103503002502001501005001.5.20001.8.20001.11.20001.2.20011.5.20011.8.20011.11.20011.2.20021.5.20021.8.20021.11.20021.2.20031.5.20031.8.20031.11.20031.2.20041.5.20041.8.20041.11.20041.2.20051.5.20051.8.20051.11.20051.2.20061.5.20061.8.2006µg/l1 m5 m10 m13 mFigure 9-9 cont'd. Total nitrogen concentration in different water layers in the watersnear Olkiluoto in the years 2000–2006. TA = Target area.

103TA Lake1/Sea091/SEA09µg/l40353025201510501 m5 m8 m1.2.20001.6.20001.10.20001.2.20011.6.20011.10.20011.2.20021.6.20021.10.20021.2.20031.6.20031.10.20031.2.20041.6.20041.10.20041.2.20051.6.20051.10.20051.2.20061.6.2006TA Lake3/Sea053b/SEA05µg/l504030201001 m5.5 m16.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006TA Lake3/Sea063a/SEA06µg/l1401201008060402001 m5 m10 m13 m16.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006Lake3/Sea08TA 3a/SEA08908070605040302010016.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006µg/l1 m5 m8.5 mFigure 9-10. Total phosphorus concentration in different water layers in the watersnear Olkiluoto in the years 2000–2006. TA = Target area.

104TA Lake3/Sea073a/SEA07µg/l40353025201510501 m5 m7 m16.2.200016.6.200016.10.200016.2.200116.6.200116.10.200116.2.200216.6.200216.10.200216.2.200316.6.200316.10.200316.2.200416.6.200416.10.200416.2.200516.6.200516.10.200516.2.200616.6.2006TA 2/SEA03Lake2/Sea03µg/l60504030201001 m5 m10 m1.2.20001.6.20001.10.20001.2.20011.6.20011.10.20011.2.20021.6.20021.10.20021.2.20031.6.20031.10.20031.2.20041.6.20041.10.20041.2.20051.6.20051.10.20051.2.20061.6.2006Sea10 SEA1025201510501.5.20001.8.20001.11.20001.2.20011.5.20011.8.20011.11.20011.2.20021.5.20021.8.20021.11.20021.2.20031.5.20031.8.20031.11.20031.2.20041.5.20041.8.20041.11.20041.2.20051.5.20051.8.20051.11.20051.2.20061.5.20061.8.2006µg/l1 m5 m10 m13 mFigure 9-10 cont'd. Total phosphorus concentration in different water layers in the watersnear Olkiluoto in the years 2000–2006. TA = Target area.In addition to the extensive regulatory surveillance programme by the nuclear powerplant, separate sampling has been performed by Posiva Oy in order to complete thebaseline study of the disposal site. The sampling points are SEA01-04, of which SEA02belong to Target area 3a, SEA03 to Target area 2 , and SEA04 to Target area 1. Thesamples were collected as near to the sea bottom as possible (approx. 1 m from seabottom).

105Table 9-2. Analysis results of seawater samples during 1989-2005 (Data by Teollisuudenvoima Oy).Sampling Date TDS Br - Cl - SO 2- 4 K Ca Mg Na Srpoint (ddmmyy) mg/lSEA01 240894 5680 10.4 3020 460 65 84 219 1740 1.2100902 5600 8.6 3050 440 59 89 220 1650 1.3171105 6060 10 3390 440 61 97 220 1750 1.4SEA02 220889 5970 11.5 3250 501 61 91 227 1730 -240894 5710 10.1 3030 440 66 80 218 1780 1.2100902 5620 8.9 3010 450 59 90 220 1700 1.3081105 5680 10 3120 440 59 93 210 1660 1.2SEA03 090902 5630 9.1 3010 440 59 90 210 1730 1.3081105 5760 10 3170 450 60 93 210 1680 1.3SEA04 090902 5340 8.6 2910 430 55 85 210 1610 1.2081105 5640 10 3080 440 58 92 200 1660 1.2In 2005 the seawater compositions in these four different sampling points were quitesimilar. The seawater sample from Target area 1/SEA04 was the least saline and had thelowest conductivity, but contained the highest amounts of ammonium, nitrate, totalnitrogen and silicate. The seawater sample from SEA01 was the most saline with thehighest conductivity too. There was no variation in sulphur concentration between thesefour sampling points: Total sulphur concentrations were 150 mg/l at every sample andsulphate concentrations 440-450 mg/l. In general, the chloride and calciumconcentrations seem to be increasing. Changes in other parameters do not give as goodindications of the direction of changes.The most important results from samplings in 1989, 1994, 2002 and 2005 are presentedin Table 9-2. The TDS value has increased slightly in SEA03, in SEA04 the increasehas been more notable, but in SEA01 it first decreased before turning upward. InSEA02 the TDS value decreased from 1989 to 2002, but then in last measurement in2005 it has remained in the level of 2002.Radionuclide concentrations in seawater have been monitored in several samplinglocations within the radiological surveillance programme maintained by the nuclearpower plant since 1977. The fallout of the 1986 Chernobyl accident is still prominent.The monitoring data tables can be found in Ikonen (2003; years 1984-2001), Roivainen(2005; years 1977-1983 and 2002-2003), and Haapanen (2005, 2006).9.2 Phytoplankton ProductionChlorophyll aThere have been relatively minor temporal and spatial variations in summertimechlorophyll concentrations, whereas chlorophyll concentrations in late summer haveincreased, especially in the 1990s. In 2004 and 2005, chlorophyll concentration and theprimary production capacity of phytoplankton have been clearly lower than in the late1990s and the early 2000s (Figs. 9-11 and 9-12). In the Olkiluodonvesi area (Targetarea 3b/SEA05) and at the mouth of the Eurajoensalmi area (Target area 1/SEA09),chlorophyll concentrations have temporarily clearly exceeded the reference values inother coastal locations.

106Phytoplankton Species and BiomassesIn the area affected by the cooling water, the flows and increases in temperature havehad an impact on phytoplankton production, which has often increased in the sea areaoff Kaalonperä (Target area 3a/SEA08) and is higher there than in the surrounding seaarea (Fig. 9-13). This can also be seen in oxygen oversaturation in the surface layers ofthe water. These changes have extended over a relatively small area. The lengthening ofthe growing period particularly in spring has increased production. The dominantgroups of species have often included cryptomonads (Cryptophyceae), diatoms (Bacillariophyceae)and others, which include, for example, unidentified unicellular algae ormonads and the ciliate Mesodinium rubrum which is a unicellular protozoa and receivesthe chromatophores it needs for assimilation from symbiotic algal cells that live in it.The total amount of plankton algae has grown in the entire sea area from the late 1980sand the early 1990s. At the same time, the difference in their biomass has decreasedbetween the sea area off Kaalonperä and the other parts of the sea area. In many years,the average biomass in summer has been highest in the Olkiluodonvesi (Target area 3b)area and lowest in the area north of Pyrekari (north of Target area 2).For many years, there has been a higher amount of blue-green algae in the cooling waterintake and discharge areas (Target areas 3a and 3b) than in the other parts of the seaarea, but otherwise these areas have not differed from the other observation sites interms of plankton algae. However, the total amounts of blue-green algae have mainlybeen small (Fig. 9-13). The dominant species among the blue-green algae has mostlybeen Aphanizomenon sp., which forms algae blooms in the sea area but does not produceany toxins there.

107Lake1/Sea09Target area 1/SEA096Target Lake3/Sea05 area 3b/SEA0565544µg/l3µg/l32211001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea06Target area 3a/SEA066Target Lake3/Sea08 area 3a/SEA0865544µg/l3µg/l32211001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea07Target area 3a/SEA076Target Lake2/Sea03 area 2/SEA0365544µg/l3µg/l32211001990199219941996199820002002200419901992199419961998200020022004Sea10 SEA10654321019901992199419961998200020022004µg/lFigure 9-11. Average chlorophyll concentration in the production layer in the watersnear Olkiluoto for July–August in the years 1990–2005.

108Lake1/Sea09Target area 1/SEA09350Target Lake3/Sea05 area 3b/SEA05350mg C/m³.d30025020015010050mg C/m³.d30025020015010050001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea06Target area 3a/SEA06350Target Lake3/Sea08 area 3a/SEA08350mg C/m³.d30025020015010050mg C/m³.d30025020015010050001990199219941996199820002002200419901992199419961998200020022004Lake3/Sea07Target area 3a/SEA07350Target Lake2/Sea03 area 2/SEA03350mg C/m³.d30025020015010050mg C/m³.d30025020015010050001990199219941996199820002002200419901992199419961998200020022004Sea10 SEA10350mg C/m³.d30025020015010050019901992199419961998200020022004Figure 9-12. Average values for primary production capacity of phytoplankton in theproduction layer in the waters near Olkiluoto for July–August in the years 1990–2005.

109Lake3/Sea06Target area 3a/SEA06600500OthersCryptomonadsGolden-brown algae and prymnesiophytesDinoflagellatesBlue-green algaeGreen algaeDiatoms4003002001000199019911992199319941995199619971998mg/m³1999200020012002200320042005Target area 3a/SEA08Lake3/Sea08600500400mg/m³30020010001990199119921993199419951996199719981999200020012002200320042005Lake3/Sea07Target area 3a/SEA07600500400mg/m³300200100019901991199219931994199519961997Figure 9-13. Average phytoplankton biomasses in the waters near Olkiluoto for thesummers (June–September) 1990–2005.19981999200020012002200320042005

110Target Lake3/Sea05area 3b/SEA05600500400OthersCryptomonadsGolden-brown algae and prymnesiophytesDinoflagellatesBlue-green algaeGreen algaeDiatomsmg/m³30020010001990199119921993199419951996199719981999200020012002200320042005Target area 2/SEA03Lake2/Sea03600500400mg/m³30020010001990199119921993199419951996199719981999200020012002200320042005Figure 9-13 cont'd. Average phytoplankton biomasses in the waters near Olkiluoto forthe summers (June–September) 1990–2005.9.3 Primary ProductionIn the waters near Olkiluoto, phytoplankton primary production was measured using an“in situ” radiocarbon method ( 14 C) in target area 3a at points SEA06 and SEA08 eighttimes per year between April and September. In 2005, as in 2004, primary productionincreased in the sea area off Kaalonperä and was approximately 20% higher than in thearea southwest of the cooling water discharge area. Primary production in the watersnear Olkiluoto was clearly lower in 2005 (13–28%) as well as in 2003 and 2004 (20–34%) than the average for the ten-year period 1990–1999 (61 g/m 2. a). In the long-term,primary production clearly increased until 2002, though there was some annual variation(Fig. 9-14). During the past three years (2003–2005), production has been clearlylower than in the late 1990s and at the turn of the century, and mainly corresponded tothe level observed in the early 1980s. However, production increased steadily from2003 to 2005.

.111Composite samples taken from the production layer have also been used for measurementsof phytoplankton primary production capacity to establish the amount of organicmatter produced by assimilation under laboratory conditions. In the waters near Olkiluoto,primary production capacity increased from the late 1970s until the late 1990s, butduring the period 2003–2005 it remained low. In 2005, primary production capacityduring the open-water season was on average 35% lower than the average in the years1995–2004. The change was greatest at the outermost observation sites (SEA10 andSEA07). However, this change might be temporary, caused by the dry periods in 2002and 2003 and the low quantity of runoff waters, for example (Turkki 2006).Chlorophyll concentrations have clearly increased in August and September, especiallyin recent years (Kirkkala & Turkki 2005). The total biomass of phytoplankton hasmostly been at its highest in May after the diatom spring bloom.g C/m 2. a908070Lake3/Sea06TA3a/SEA06Lake3/Sea08TA3a/SEA08Lake3/Sea06TA3a/SEA06Lake3/Sea08TA3a/SEA0860504030201001990199119921993199419951996199719981999200020012002200320042005Figure 9-14. Actual primary production by phytoplankton during the growing period(April–September) in the waters near Olkiluoto. Survey points Target area 3a/SEA06and Target area 3a/SEA08 in the years 1990–2005.The Quality of Waters Flowing into the Olkiluoto Sea Area from Other Parts of theSeaDue to the main flow directions in the Baltic Sea, the waters from the Baltic Main Basinand the Gulf of Finland and the nutrient-rich waters from the catchment of the ArchipelagoSea flow partly through the Archipelago Sea into the Bothnian Sea. The mainflow direction dominating in the coastal sea area of the Bothnian Sea is thus from southto north. This means that it is likely that water mainly flows into the water area nearOlkiluoto from the Haapasaarenvesi area south of it, which is a shallow bay bounded bythe mainland and islands (Target area 4). Waters flowing to the north from the otherparts of the Rauma sea area are likely to have an impact on the open sea areas in theOlkiluoto region.

112Water quality in the Haapasaarenvesi area has only been studied since 2006. On thebasis of the summertime chlorophyll and total phosphorus concentrations, the area canbe classified as eutrophic. Based on the results for 2006, the Haapasaarenvesi area isclearly more eutrophic than the waters near Olkiluoto and is, in this respect, by andlarge similar to the eutrophic Syväraumanlahti bay, which belongs to the Rauma seaarea. In 2006, phytoplankton measurements were also be carried out in the Haapasaarenvesiarea.9.4 FloraAquatic flora in the sea area off Olkiluoto has been monitored since 1975 (Ekengren etal. 1985, Keskitalo & Ilus 1987), with the most recent survey being carried out in 2004(Kinnunen & Oulasvirta 2004). The aquatic flora in the Olkiluoto sea area ranges fromthe algae dominant community in the outer archipelago typical of hard bottoms to thevascular plant dominant community in the Olkiluodonvesi area typical of soft bottoms.On the basis of the vegetation survey lines studied in the 1990s, the effects of eutrophicationcould be observed in the area affected by the cooling water. The proportions ofdifferent species have clearly changed, and perennial algae and plants have been replacedby annual species, mainly filamentous algae. In the early 1990s, Enteromorphaspp. were abundant and this caused problems in cooling water uptake, but in the late1990s the amount of these green algae decreased significantly (Mäkinen et al. 1992,Vahteri & Jokinen 1999).In the most recent vegetation survey (Kinnunen & Oulasvirta 2004), a total of 24aquatic plant species were found in the area, the majority of which (16) were algae andthe remaining were vascular plants, plus one aquatic moss species. The most commonspecies included the brown algal species Ectocarpus silicusosus/Pilayella littoralis, thefilamentous green algal species Cladophora glomerata, and the vascular plant speciesspiked water-milfoil (Myriophyllum spicatum) and fennel pondweed (Potamogetonpectinatus). Spiked water-milfoil and fennel pondweed are plant species typical of softbottom areas, and they were particularly found in the old survey lines near the powerstation (Fig. 9-15). Compared with the previous survey (Vahteri & Jokinen 1998), theamount of loose sediment material found on the bottom had increased. The eutrophicationcaused by the power station can clearly be seen in the old vegetation survey lines,but the effects are limited to the sea area that remains unfrozen during winter. Comparedto 1997, the diversity of species found in the old vegetation survey lines hasclearly reduced.

113Figure 9-15. The proportions of different types of vegetation in the old survey lines(SBT03-SBT04) and in the new reference lines (SBT06-SBT07). The line pairs SBT03-06 and SBT04-07 correspond quite well in terms of openness of the shore as well as theprofile and quality of the sea bottom. The diversity of species in lines SBT03 and SBT04has clearly been reduced since 1977.9.5 Bottom FaunaThere is some annual variation in the bottom fauna species found in the waters nearOlkiluoto as in other sea areas. This is caused by factors such as weather conditions andfluctuations in the populations of individual species. In recent years, the variation hasincreased due to the accumulation of algae and plant residues in the deep areas, wherethey consume the limited oxygen resources of the water mass as they degrade. The productionof aquatic flora and bottom algae has increased in the shallow areas due toflows, improved nutrient provision and a longer growing period.The state of the sea bottom in the cooling water discharge area in the sea area off Kaalonperä(Target area 3a) clearly deteriorated in the late 1990s and especially in the early2000s due to the increase in algae residues and the intermittent lack of oxygen causedby their degradation. The species composition changed and the diversity of species wasreduced. In addition, their biomass almost collapsed after 1997 (Kirkkala & Turkki2005). The changes in the biomass have been attributable to the population fluctuationsof the bivalve Macoma balthica in particular, which has been the dominant species onmud bottoms (Fig. 9-16). In many years, size distributions have shown a lack of largebivalves. The bivalve populations have probably been destroyed due to lack of oxygen.In recent years, the oxygen conditions in the water near the bottom have been betterthan normal which has also been reflected in the recovery of bottom fauna communities

114(Table 9-3, Fig. 9-16). Algae production and thus also the degradation of algae has beenlower than normal.In the bottom fauna samples taken from the Eurajoensalmi (Target area 1) in 1996, bottomfauna species typical of coastal waters were found (such as the Baltic bivalve andthe North American polychaete Marenzelleria viridis). On the one hand, no species indicatingpollution were found, but on the other hand, no species indicating a clean seabottom were found either, presumably due to the shallowness of the area (Jumppanen &Räisänen 1998, Ikonen et al. 2003).Table 9-3. Number (N; individuals/m 2 ) and biomass (B; g/m 2 ) of bottom fauna at differenttarget areas (TA) and observation sites (SEA) in the years 1990–2005.TA1/SEA09 TA3b/SEA05 TA3a/SEA06 TA3a/SEA08 TA3a/SEA07 TA2/SEA03Year N B N B N B N B N B N B1990 1826 136.9 2910 126.2 3690 275.1 4103 257.3 569 4.2 1992 17.31991 1070 111.6 2185 145.4 2640 187.3 2440 217.8 211 13.2 1540 27.41992 1383 215.4 1784 214.4 1528 143.6 2063 172.5 747 5.1 1271 149.91993 1227 125.7 1940 186.8 3624 258.7 2475 247.2 234 1.9 870 16.11994 1260 172.9 2810 234.1 2263 343.5 3657 323.3 2219 26.6 1817 19.81995 3222 201.0 2386 221.6 3523 415.5 3423 391.7 * * 2665 224.21996 3590 161.3 5441 184.9 5040 184.6 1561 183.4 2866 4.3 992 98.61997 2029 154.2 2453 142.1 413 112.0 1795 253 2977 12.2 2241 53.91998 4783 112.3 2375 158.2 5843 84.6 9634 11.6 758 11.3 1271 96.51999 2520 141.9 2275 101.2 7526 68.1 1907 20.5 702 31.7 1271 92.12000 3423 188.8 2754 64.2 4126 6.0 6233 15.2 123 0.5 1572 53.52001 3033 78.2 2107 35.0 2899 48.1 3903 18.9 1617 5.6 2531 157.42002 4750 88.6 3300 42.8 624 33.5 580 0.8 959 1.0 2074 100.62003 3289 118.9 4003 47.1 769 48.6 5352 4.4 1728 2.5 2553 64.52004 1929 62.1 2475 59.7 3334 52.3 3323 35.4 5542 50.2 5062 150.62005 2040 66.5 2576 75.6 4505 55.6 1516 122.1 2286 154.7 4449 198.4* Sandy bottom, no samples

.115g/m 2450MacomaOthers400350300250200150100500198219841986198819901992199419961998200020022004Figure 9-16. The biomass (fresh weight) of soft-bottom fauna and the proportion (g/m 2 )of Baltic bivalves at the Target area 3/SEA08 in the years 1982–2005.9.6 Fish StocksThere are some 50 different fish species in the Bothnian Sea, and about half of these aremarine fish species and the other half are fresh-water fish species. The low salinity ofthe Bothnian Sea is a limiting factor for most marine fish species, and thus the speciescomposition of fish stocks varies considerably between the different parts of the BothnianSea. The highest number of species is found in the coastal and archipelago zone.The most important fish species in the entire area is the Baltic herring (Lehtonen2005a).In the sea area off Olkiluoto, the fish species and fishing activities are monitored inaccordance with fisheries monitoring programmes approved by the authorities. Fisheriesmonitoring in the waters near Olkiluoto includes fishing activity surveys conductedin specific years, commercial fishery surveys carried out every two years, age andgrowth analyses of fish, assessment of changes in spawning grounds by studying algaesurvey lines and the occurrence and mortality of Baltic herring spawn in its spawningshores (Kirkkala 2005).Commercial fishery is practiced in the sea area off Olkiluoto throughout the year. Theeconomically most important species are European whitefish, perch and pike. The mainmethod used is net fishing. According to the fishing activity survey conducted in 2001,commercial fishing accounts for 70% and recreational fishing and fishing for householduse for 30% of the total catch of fish (Piispanen & Lintinen 2003).In a test fishing conducted in 2002, the most common species was perch, which accountedfor 53% of the total number of the fish caught. The second most common spe-

116cies was roach, which accounted for 18% of the total number of the fish caught. Comparedto 1993, the catch of roach has clearly increased (Piispanen & Lintinen 2003).According to the commercial fishery survey conducted in 2005 (Lintinen 2006), theeconomically most important species were perch and pikeperch as well as salmon andtrout. Previously, Baltic herring had an important role, but due to its low profitabilitythe fishing of Baltic herring has reduced to a fraction of its previous level. In 2005, almosthalf of the total catch consisted of perch (Table 9-4). The next highest catcheswere those of pike, roach and Baltic herring. The proportion of the combined catch ofsalmon and trout has increased ten-fold compared to 2003, thanks to the introduction ofa salmon catching device resistant to attacks by seals.The stocks of salmon and trout have improved somewhat in recent years. The size of thestock depends on the amount of stocking and its success. The stock of European whitefishis relatively good, and the stock of flounder has strengthened. The stock of perch isvery strong, and no clear differences were observed in the growth of perch caught in thecooling water discharge area and those caught in the reference area. The stock of roachhas also increased and so has that of pike to some extent. Pikeperch has come into thearea; previously it was found only occasionally (Lintinen 2006).The monitoring of fish stocks has shown that general effect of the cooling waters is toincrease fish stocks and no fish species stock can be considered to have decreased dueto the discharge of cooling water into the sea. During winter months, trout and Europeanwhitefish have been found in the unfrozen water area caused by the cooling water.The stock of perch is abundant, and it is also caught in high amounts. In addition, pikeperchhas appeared among the species caught (Lintinen 2006).Table 9-4. Commercial fishery catch in the sea area off Olkiluoto by fish species in2001, 2003 and 2005 (Lintinen 2006).2001 2003 2005kg % kg % kg %Baltic herring 2,595 6.9 4,628 13.1 900 7.0European 2,992 8.0 2,819 8.0 693 5.3whitefishSalmon, trout 870 2.3 203 0.6 770 5.9Pike 4,922 13.2 3,082 8.7 1,496 11.6Bream 6,955 18.6 6,232 17.6 608 4.7Ide 570 1.5 612 1.7 1 0.0Roach 3,580 9.6 1,890 5.3 1,036 8.0Burbot 1,871 5.0 1,245 3.5 641 4.9Pikeperch 1,002 2.7 2,965 8.4 643 5.0Perch 10,522 28.2 11,271 31.9 6,031 46.6Flounder 893 2.4 27 0.1 116 0.9Rainbow trout 242 0.6 8 0.0 6 0.0Other 328 0.9 385 1.1 10 0.1Total 37,342 100.0 35,367 100.0 12,949 100.0

117According to the commercial fishery survey, the greatest nuisance to fishery is causedby seals which hinder fishing between September and May, in particular (Piispanen &Lintinen 2003). The grey seal stock in the Baltic Sea has, indeed, increased six-foldduring the last 30 years. The boldest seals come up into the inner bays near the coastand feed from the commercial fishermen’s catching devices destroying these in theprocess. In some areas, fishing may be prevented completely at times (Salonen 2005).9.7 Load Coming into the Olkiluoto Sea AreaRiver Waters Loading into the SeaThe total area of the watershed of the river Eurajoki, which flows through the municipalitiesof Eura, Kiukainen and Eurajoki, is 1,336 km 2 , and its lake percentage is 13%.The watershed includes the largest lake in southwestern Finland, Lake Säkylän Pyhäjärvi(154 km 2 ), where the river, which is about 52 kilometres long, starts. In thecatchment of the river Eurajoki (excluding the catchment of Lake Pyhäjärvi), fields accountfor some 28% and forests for almost 70% of the total area. The most importanttributaries of the river Eurajoki are the river Köyliönjoki, which starts from LakeKöyliönjärvi (catchment area 264 km 2 ), and the river Juvajoki (86 km 2 ), which joins thelower course of the river Eurajoki.Wastewaters from the food and paper industries and local settlements are fed into theriver Eurajoki. The load caused by these waters has reduced in recent years thanks toimproved wastewater treatment in larger units. During dry periods, water is drawn fromthe river Eurajoki into the river Lapinjoki for the town of Rauma and industry. Duringdry periods, water is also run from the river Kokemäenjoki through the river Köyliönjokiinto the river Eurajoki to ensure sufficient water volumes.At its upper course, the river Eurajoki is classified as good or satisfactory in terms ofgeneral usability. At times, turbid and nutrient-rich additional waters flow into the riverfrom ditches and tributaries. In fact, diffuse loading is the most important factor affectingthe water quality in the lower course of the river Eurajoki, but especially at timeswhen the discharges are low, the wastewaters from the municipalities and industryalong the river have a significant impact on the state of the river. The middle part of theriver below the outlet of the river Köyliönjoki is classified as passable. At the lowercourse, the water of the river Eurajoki has, for very short periods, been very acid due toalum leaching from the soil. However, at most observation sites, the river water hasbeen at most slightly polluted and hygienically passable. The lower part of the riverEurajoki has mainly been satisfactory in terms of general usability (Suomen ympäristökeskus& Alueelliset ympäristökeskukset 2005).In the period 2000–2005, the river Eurajoki carried on average 19.6 tonnes of phosphorusand 619 tonnes of nitrogen into the sea annually (Table 9-5). According to the VEPSsystem developed by the Finnish Environmental Administration for the estimation andcontrol of nutrient loads to watercourses, about half of the nutrients in the river Eurajokicome from agriculture, one tenth comes from point sources and about one fifth is causedby natural leaching.

118Table 9-5. Nutrient transport and mean flow in the rivers Eurajoki and Lapinjoki in theyears 2000–2005. Source: Southwest Finland Regional Environment Centre (Herttainformation system).River EurajokiYear Phosphorus t/y Nitrogen t/y MQ m 3 /s2000 42.3 1014 11.82001 21.8 577 8.02002 19.5 370 6.32003 4.4 241 2.92004 6.3 606 5.82005 23.1 903 9.3Average 2000-2005 19.6 619 7.4River LapinjokiYear Phosphorus t/y Nitrogen t/y MQ m 3 /s2000 6.4 231 4.82001 5.9 244 3.42002 3.7 140 2.22003 1.8 74 1.32004* 2.6 212 3.02005 4.7 234 3.7Average 2000-2005 4.2 189 3.1*In 2004 only two water quality measurements were carried out in the river Lapinjoki.The river Lapinjoki (watershed 462 km 2 ) has its origins in forest and peatland areas andflows through the municipalities of Eura and Lappi into the Bothnian Sea. There arenumerous small lakes in the Lapinjoki watershed. There is one hydropower plant on theriver. The water is brown and rich in humus and contains high levels of iron and organicmatter. The general usability of the river is mostly classified as satisfactory. The nutrienttransport in the river Lapinjoki is mainly caused by diffuse loading. In the period1990–2002, the river Lapinjoki carried on average 5.3 tonnes of phosphorus and 230tonnes of nitrogen into the sea annually (Table 9-5). Its phosphorus transport is on averageone fifth that of the river Eurajoki. However, the share of the nitrogen transport isrelatively greater. It is one third that of the river Eurajoki. This is probably attributableto the larger proportion of peatlands in the Lapinjoki watershed (Kirkkala & Turkki2005).The Near-Catchment of the Olkiluoto Sea AreaEstimated roughly on the basis of terrain maps, the surface area of the near-catchmentof the Olkiluoto sea area is approximately 15.5 km 2 . Fields account for only 4% (0.6km 2 ) of this area. According to Rekolainen (1989), the load coming from the fields of acatchment can be assessed on the basis of the surface area of the fields. According to hisstudies, the annual phosphorus load caused by fields is 0.9–1.8 kg/ha and the annualnitrogen load is 8.0–20 kg/ha. As the surface area of fields in the near-catchment ofOlkiluoto is 0.6 km 2 (60 ha), according to Rekolainen’s model, the annual phosphorusload from the fields would range from 54 to 108 kg and the annual nitrogen load wouldrange from 480 to 1,200 kg. Rekolainen has estimated that natural leaching is 10 kgphosphorus/km 2 and 250 kg nitrogen/km 2 per year. In the near-catchment of Olkiluoto,natural leaching would be 149 kg of phosphorus and 3,700 kg of nitrogen per year,roughly estimated. The total amount of phosphorus load coming from the fields and

119caused by natural leaching is approximately 1% of the phosphorus load coming fromthe river Eurajoki. The corresponding total nitrogen load (fields and natural leaching) isclearly less than 1% of the nitrogen load brought by the river Eurajoki.Local Wastewater LoadTeollisuuden Voima Oy’s biologically-chemically treated sanitary waters are led intothe cooling water discharge area from the Olkiluoto nuclear power plants. The loadcaused by these waters reduced considerably in 1996, when the former chemical treatmentplant was replaced by a new facility equipped with a biological rotor. In the years2000–2005, the annual phosphorus load caused by the sanitary waters has been 8–14.2kg and the annual nitrogen load 803–2,738 kg. In 2005, the load caused by the sanitarywaters was clearly higher than earlier in the 2000s, mainly due to the construction siteof the third power plant unit at Olkiluoto (Turkki 2006). It employs several hundredpeople.During the period 1982–1997, there was a fish farm (Olkiluodon Lohilaitos) operatingin the waters near Olkiluoto (Kirkkala & Turkki 2005). The load caused by it was at itshighest 220 kg of phosphorus per year (in 1994) and 1,830 kg of nitrogen per year (in1993).Atmospheric DepositionThe load on waters caused by atmospheric deposition is calculated on the basis of theamount of nutrients deposited directly on the water surface. Most of the material depositedon the soil is presumably absorbed by the vegetation and the soil. It is difficult toassess which proportion of this material is carried into the waters and this amount isthus considered to be included in natural leaching. According to measurements carriedout by the Finnish Environmental Administration, the bulk deposition of nutrients asaverage values for the Jokioinen, Peipohja and Tvärminne stations was as follows in theyears 2000–2005: ammonium and nitrate nitrogen 433 kg/km 2 total nitrogen 534 kg/km 2 total phosphorus 10 kg/km 2The values for the deposition of nutrients contained in precipitation vary considerablybetween different years and locations. According to the data on the deposition of nutrientson forests (Haapanen 2006) in the Olkiluoto area, the bulk deposition of nitrogen inthe open area would be considerably lower than the average values given above; thetotal nitrogen deposition was 351 kg/km 2 /a and the combined ammonium and nitratenitrogen deposition was 289 kg/km 2 /a, on average for the years 2004 and 2005.

120

12110 ECOSYSTEM MODELS FOR LAND AND SEA10.1 Ecosystem Models and Carbon CycleConceptual ecosystem models can be used to describe the flows of matter in an ecosystem,the pools of the matter and the interactions between different parts of the ecosystem.When these models are quantified, a choice of relevant elements must be done.Carbon is a relatively constant element in the organic matter, and constitutes a large partof it, which makes it a good choice for the quantification calculations. The carbon cycleis reasonably well understood, but many uncertainties still remain (Liski 1997, Monni etal. 2004, 2006, Peltoniemi 2005; see a list in Chapter 12.2).Ecosystems are sources of carbon that release it into the atmosphere, but they are alsosinks that take up carbon from the atmosphere due to various chemical, physical,geological and biological processes. Globally the total amount of carbon in the oceans isabout 50 times greater than the amount in the atmosphere, and is being exchanged withthe atmosphere on a time-scale of several hundred years. In the terrestrial environment,the stock in plants is 466–654 Pg and in soil is 2011–1567 Pg, depending on the dataand method of estimation (IPCC 2001). In Finland the biggest reservoirs of organic carbonare mires, which contain 3.2–5.6–6.3 Pg tonnes of carbon (Virtanen et al. 2000,Minkkinen 1999, and Hillebrand 1993, respectively), depending on mire definition(geological or botanical/silvicultural) and method of estimation. The forest soils containthe second largest amount, 1.0–1.5 Pg, while forest stands contain around 0.65 Pgtonnes of organic carbon (Kauppi et al. 1997, Liski & Westman 1997). The amountfound in lake sediments has been estimated to be 0.7–0.9 Pg (Pajunen 2000).According to the study of Ilvesniemi et al. (2002), the contents of carbon in forest soilsare largest in southwestern, eastern and northeastern Finland. The higher contents insouthwestern Finland probably reflect the influence of greater tree growth and forestproductivity while higher contents in eastern and northern Finland probably reflect theinfluence of low decomposition rates. Sphagnum cover, which indicates moisture status,was clearly the most important factor explaining the humus layer carbon contents whilein the mineral soils it was the content of fines. The carbon concentrations plottedagainst the soil age (Starr 1991) showed that around 750 years is needed for carbonconcentrations to reach equilibrium and it clearly took longer in the deeper layers(1,200–1,300 years) than in the surface layers of less than 10 cm.The continuous postglacial uplift and shallow coast areas of sea bottom sedimentsmakes primary succession along shores very fast at Olkiluoto area (Rautio et al. 2004).In particular climatic and topographical conditions, vegetation succession turns to newecosystems in the future (Ikonen et al. 2004) and can also change many areas frompresently acting as sinks to become sources of atmospheric CO 2 . The carbon stocks ofsoils may change remarkably over a short period of time (Liski 1997, Ilvesniemi et al.2002).The type of vegetation that is developing is of great importance to the transport of organiccarbon compounds. The relative abundance of wet and dry areas is important for

122the carbon release-accumulation balance. In mires and lake sediments, decomposition isslow due to oxygen deficiency, and organic production exceeds decomposition, i.e.,carbon accumulates. In drier areas, decomposition of organic material is fast, increasingthe release of carbon to the atmosphere as carbon dioxide. The net effect of these twoopposing processes depends upon the relative area of the different ecosystems togetherwith the respective rates of carbon fixation and decomposition. (Kautsky 2001).There are no Olkiluoto-specific results for the whole carbon cycle in the different ecosystemsyet. In the following, the first versions of conceptual ecosystem models arepresented for the terrestrial and sea ecosystems, and the models are quantified whenpossible. In future versions, other central elements such as nitrogen and phosphorus,should also be taken into account. By estimating stocks and flows of other elements,having various stoichiometric relationships with carbon, errors in estimation of stocksand flows of energy, matter, nutrients and contaminants may be minimised. Althoughthe behaviour of radionuclides associated with organic matter is unique for each radionuclide,a major radionuclide pathway to humans in the safety assessment is via digestionand thus follows the organic matter in the ecosystem. (Lindborg et al. 2006,Löfgren et al. 2006, Kumblad et al. 2006).10.2 Terrestrial VegetationThe major pools and fluxes of terrestrial ecosystem on Olkiluoto are presented in Fig.10-1. Concerning vegetation, the conceptual model was quantified only for forests, dueto lack of site-specific parameters in the case of shore meadows and agricultural fields.The soil carbon stock was not estimated in this version of biosphere description.

123UptakeEmissionNet productionConsumptionGPPTranspirationHumansHerbivoresCarnivoresPlantsTranslocationto rootsRoots/FungiLitterDecompositionSoil carbonEmissionLateraltransportFigure 10-1. Major pools and fluxes of carbon on the terrestrial areas of main island ofOlkiluoto. GPP (Gross Primary Production) is the amount of energy fixed by photosynthesisover a defined time period.The biomass of terrestrial vegetation was estimated in two different ways. First, thebiomass of tree stands was derived from stand volumes (Rautio et al. 2004) by forestcompartments (corresponding to the forested vegetation polygons) using Biomass ExpansionFactors (BEF) by Lehtonen et al. (2004a). Pine BEFs for stumps and coarseroots (> 2 mm) were also used for deciduous trees. The biomass of leaves in deciduoustrees was estimated according to studies of Parviainen (1999) and Ilomäki et al. (2003).The understorey biomass in forest compartments was estimated based on models byMuukkonen and Mäkipää (2006), and by assuming that below-ground part counted for70% of the total understorey vegetation biomass (Muukkonen & Mäkipää 2006).Second, due to the fact that FET plots have been measured tree by tree (Saramäki &Korhonen 2005), the biomass of different tree compartments on FET plots (originally560, reduced to 545 due to construction activities) was derived using Swedish models(Marklund 1988), except for fine roots, whose biomass was calculated according toHelmisaari et al. (2007), and for leaves, the biomass of which was estimated using modelscreated in Finnish Forest Research Institute, by Jaakko Repola & Risto Ojansuu.Biomass of coarse roots and stumps of deciduous trees were estimated using the samemodels as for pine (Marklund 1988). The biomass distribution in tree stands is presentedas carbon (kg/m 2 ) by stand age class, site type and dominant tree species in Tables10-1 and 10-2. The understorey vegetation coverages of the FEH plots were convertedto biomasses using models created in Finnish Forest Research Institute, by Maija

124Salemaa. Biomass of ground vegetation is also presented as carbon (g/m 2 ) by stand ageclass, site type and dominant tree species in Tables 10-3 and 10-4.The carbon content of vegetation was assumed to be 50% of dry mass (Hakkila 1989,Nurmi 1993, Bolin et al. 2000, Prentice et al. 2001), although Olkiluoto-specific datawas available for tree foliage and ground vegetation species based on the FEH plotmeasurements in 2005 and 2006 (C content 51–55% in foliage and 47–52% in groundvegetation, respectively (Tamminen et al. 2007)).Net production of the tree layer was calculated using measured growth estimates (datafrom Rautio et al. 2004) and BEFs by Lehtonen et al. (2004a), see Table 10-5. Net productionof ground vegetation was estimated with turnover rates (Muukkonen & Lehtonen2004).Estimates of annual fluxes of net production (growth) and litter production are presentedin Tables 10-5 and 10-6. Litter production estimates are based on turnover ratecoefficients of biomass compartments (Lehtonen et al. 2004b, Muukkonen & Lehtonen2004, Starr et al. 2005, Liski et al. 2006, Muukkonen & Mäkipää 2006).The biomass, carbon content, and net production of the shrub layer were not estimated,because of the lack of suitable generic models.According to the calculations by vegetation compartments the biomass of terrestrialvegetation in forest compartments varied between 0.14 and 28.4 kg/m 2 mean value being7.3 kg/m 2 . Accordingly, carbon content varied between 0.07 and 14.2 kg/m 2 , and thehighest values were observed in the Natura conservation area (Fig. 10-2). The meancarbon content in Scots pine, Norway spruce and deciduous dominating stands was 0.8,1.2 and 1.5 kg/m 2 , while the maximum carbon content was 9.1, 9.9 and 11.7 kg/m 2 , respectively.The corresponding values for understorey vegetation were: mean 0.13 andmaximum 0.32 kg C/m 2 . The total carbon content was 24,139 Mg in the terrestrial vegetationof the forest compartments on the Olkiluoto Island. The combined net productionof the trees and understorey vegetation varied from 49 to 763 being on average 302 gC/m 2 /a (Fig. 10-3).Based on FET plot measurements, the highest mean carbon content 10.2 kg/m 2 wasfound in 81–100-years-old spruce-dominated forests (Table 10-1). Mean carbon contentin tree stands increased from young and infertile sites to more fertile and older ones(Table 10-2). On average, the stem with bark accounted for 43, branches for 22, foliagefor 15, stump for 5 and roots for 15% of the total tree biomass on FET plots. Theamount of carbon bound in ground vegetation was clearly less than in trees (mean value0.10 kg/m 2 , Tables 10-3 and 10-4).

125Figure 10-2. The biomass distribution of the terrestrial vegetation (kg C/m 2 ) by forestcompartments on Olkiluoto Island, based on Biomass Expansion Factors (Lehtonen etal. 2004a).Figure 10-3. Net production of the tree layer and understorey vegetation on OlkiluotoIsland.

126Table 10-1. Mean carbon content (kg/m 2 ) in tree stands (below-ground parts included)of the forest study area on Olkiluoto main island by dominant tree species and age class(based on calculated biomass distribution on FET plots and carbon coefficient estimate0.50).Table 10-2. Mean carbon content (kg/m 2 ) in tree stands (below-ground parts included)of the forest study area on Olkiluoto main island by site types and age class. Site types:grove, grove-like, fresh, dryish, dry and extremely infertile mineral soil types, all withcorresponding mire and drained peatland types. Rocky soils include also fine sandy soiland stony soil. Finnish site type abbreviations are presented in parentheses.Age class, yearsSpecies 1- 21- 41- 61- 81- 101- 121 Total20 40 60 80 100 120 -Pine 2.1 4.9 5.0 6.3 3.1 3.5 4.0 3.9Spruce 2.3 5.0 6.8 7.7 10.2 8.9 9.5 6.4Birch 2.0 3.2 6.1 7.5 9.2 3.3Otherbroadl.2.5 5.5 6.0 8.1 5.1Age class, yearsSite type 1- 21- 41- 61- 81- 101- 121 Total20 40 60 80 100 120 -Grove (Lh) 1.8 4.9 6.8 4.3 5.5Grove-like (OMT) 2.6 5.4 7.0 8.8 14.3 14.3 6.3Fresh (MT) 2.2 4.8 6.4 7.6 8.5 8.9 5.9 5.0Dryish (VT) 1.7 4.1 5.0 4.8 6.0 7.5 10.7 3.3Dry (CT) 2.2 1.9 1.8 4.5 2.9 5.0 2.7Infertile (ClT) 1.3 2.7 3.7 2.6Rocky soils 1.6 2.1 1.4 1.9 5.2 2.4Table 10-3. Mean carbon content (g/m 2 ) in ground vegetation (below-ground parts included)of the forest study area on Olkiluoto main island by dominant tree species andage class (based on calculated biomass distribution on FEH plots and carbon coefficientestimate 0.50).Age class, yearsSpecies 1-20 21- 41- 61- 81- 101- 121- Total40 60 80 100 120Pine 117.6 127.3 140.2 205.4 118.2 159.2 119.0 130.9Spruce 89.9 92.0 93.6 99.0 65.8 69.5 88.4Birch 112.1 90.1 179.1 107.7Otherbroadl.67.2 101.8 39.1 61.0

127Table 10-4. Mean carbon content (g/m 2 ) in ground vegetation (below-ground parts included)of the forest study area on Olkiluoto main island by site types and age class(based on calculated biomass distribution on FEH plots and carbon coefficient estimate0.50). Site types: grove, grove-like, fresh, dryish, dry and extremely infertile mineralsoil types, all with corresponding mire and drained peatland types. Rocky soils includealso fine sandy soil and stony soil. Finnish site type abbreviations are presented in parentheses.Age class, yearsSite type 1-20 21- 41- 61- 81- 101- 121- Total40 60 80 100 120Grove (Lh) 102.2 102.2Grove-like (OMT) 108.7 84.5 73.5 58.6 62.9 69.5 82.1Fresh (MT) 86.8 132.8 103.5 144.5 69.6 110.7Dryish (VT) 196.1 196.1Dry (CT) 227.2 159.2 181.9Infertile (ClT) 163.2 163.2Rocky soils 128.1 118.2 74.7 114.3Table 10-5. Estimated net production of plants (below-ground parts included) of theforest study area on Olkiluoto main island by plant species/group.Net production Mg C/ha/ypine spruce decid. g-veg. sumMineral soils 0.74 0.83 0.54 0.75 2.86Peatlands 0.22 0.63 0.54 1.04 2.42Table 10-6. Estimated litter production of plants (below-ground parts included) of theforest study area on Olkiluoto main island by plant species/group. Litter productionincludes also natural mortality.Net production Mg C/ha/ypine spruce decid. g-veg. sumMineral soils 0.75 0.62 0.50 0.75 2.61Peatlands 0.32 0.23 0.81 1.04 2.39By combining the results of net production and decomposition it is possible to make arough estimate of the prevailing "natural" carbon balance of the Olkiluoto main island.Here a general assumption of decomposition was used, defining that 95% of litter willdecompose in 100 years and the remaining 5% will form slowly decomposing humus.Assumption is based on Yasso simulations made in national inventory report (NIR)(Greenhouse... 2006) of Finland under the UNFCCC (United Nations Framework Conventionon Climate Change). Further according to NIR decomposition emissions of humusand peat (heterotrophic soil respiration) were estimated to be 0.18 and 0.73 MgC/ha/y, respectively. Results of this simple calculation are shown in Table 10-7.Fellings were ignored in these calculations, mainly because statistics about the volumeswere not available.

128Table 10-7. Estimated carbon balances (below-ground parts included) of the foreststudy area on Olkiluoto main island by plant species/group. Negative sign indicatescarbon emission.Net production Mg C/ha/ypine spruce decid. g-veg. emission sumMineral soils 0.04 0.24 0.07 0.04 -0.18 0.20Peatlands -0.05 0.43 -0.19 0.05 -0.73 -0.5010.3 Terrestrial FaunaIn the case of terrestrial fauna, there existed site-specific data only of estimated populationsizes and game bags. The distribution of fauna within the island was not known,nor were there any parameters concerning animal weights, element concentrations, consumptionhabits and amounts, or production. Thus only very simplistic quantified modelscould be presented. In this report, it was decided to present a model of moose whichis the largest mammal on the island. The budget was calculated for the year 2002. It isnotable that the changes on such a small island may be great: in 2003 no moose werereported shot. In order to be able to present more realistic models, more data is neededfor several species, especially small and medium sized mammals, birds and those invertebratesthat dominate in biomass.The applied parameters are presented in Table 10-8. Generic parameters are mostlybased on the reports by SKB (Lindborg 2005a). C in respiration is a residue of otheramounts. It was not possible to give estimates on an area basis, as the distribution ofmoose population over the island is not known.Table 10-8. Parameters used for calculation of carbon cycle in moose.Parameter Value and unit ReferencePopulation before hunting 16 animals Haapanen 2006, Table 8-4seasonGame bag 10 animals Haapanen 2006, Table 8-4Food consumption 14 kg/day, 3.5 kg C/day Lindborg 2005aC in faeces 50% of C in consumed food Lindborg 2005aC content of a moose 10% Lindborg 2005aCarcase, % of an animal 55 Kairikko 1981 & own estimateHide, % of an animal 8 Kairikko 1981 & own estimateHead, intestines, cloven 37 Kairikko 1981 & own estimatehooves, % of an animalBones, % of carcase 45 Own estimate based on severalother slaughter animalsand expert knowledgeDivision of animals into males,females, and same year offspring3-6-7 Nygrén 1996

129Figure 10-4. Preliminary estimates of the carbon cycling in moose population inOlkiluoto.10.4 Sea EcosystemsCarbon is found in water in the form of dissolved inorganic carbon and dissolved organiccompounds, and in various particles. The vertical and temporal variation in theconcentration of inorganic carbon in water is connected with the activity of organismsin water. The absorption of inorganic carbon is primarily linked with assimilation,whereas respiration and decomposition release inorganic carbon compounds into thewater. Carbon dioxide is dissolved in water and forms bicarbonates and carbonates.Aquatic organisms not only use carbon for assimilation but also calcium carbonate toconstruct shells and supporting hard body parts. After the organisms die, calcium carbonateis redissolved in the water, and carbonate precipitates as calcite and dolomite.Most of the earth’s carbon reservoirs are found in persistent carbonate compoundsbound in sediments and the bedrock (Voipio 1981).There were no Olkiluoto-specific carbon analyses of the sea ecosystems available at thistime. The calculation of amounts of biomasses in a certain spot or volume of sea is alsofar more difficult than in the case on forest ecosystems. The quantification, even withgeneric parameters, was thus omitted here. However, it is believed that the carbon balancespresented in SKB's work for the Forsmark area (Lindborg 2005a) reflect to some

130extent also the situation at Olkiluoto. Figure 10-5 presents the qualitative carbon cyclefor the sea areas adjacent to Olkiluoto.WATER PHASEHCO 3 / CO 2PRODUCERS- PhytoplanktonCO 2DECOMPOSERS- Bacteria- Fungi- YeastsCONSUMERS- Zooplankton- FishCO 2DISSOLVEDORGANICCARBONDETRITUSCO 2DECOMPOSERSPOMCONSUMERSCO 2SEDIMENTCONSUMERS- Bottom fauna- FishDECOMPOSERS- Bacteria- Fungi- YeastsABIOTIC ORGANIC CARBONactive process(respiration, nutrient uptake, etc.)passive process(autolysis, sedimentation, etc.)internal components of the system(biomass, storage, etc.)different parts of the system:water phase, sediment andcarbon dioxide cycleFigure 10-5. Carbon cycle in sea areas, modified from Voipio (1981). POM denotesparticulate organic matter.

13111 IDENTIFICATION OF RELEVANT LIMNIC ECOSYSTEMSGiven the scarcity of the current limnic systems, little can be said about their properties.The land up-lift driven terrain development will, however, increase the amount offreshwater basins during the future millennia, making these very important for the modelling.Thus, water bodies and rivers of similar characteristics as the ones expected infuture were searched for in nearby areas. This was done with help of maps and GIStools. The identified potential reference water bodies are presented in Fig. 11-1 and thesea areas and potential reference lakes are listed below:Sea areas, currently surrounded by islands, which are going to be flads and/or glos Western and northern parts of Olkiluodonvesi, develop toward a glo Sorkanlahti, develops toward a flad Haapasaarenvesi, develops toward a flad/gloBays with minor sea connection Mustalahti Haapasaarenlahti/NurmenlahtiPotential reference lakes Kaarojärvi in Rauma Vuonajärvi in Eurajoki Pinkjärvi in Eurajoki/Luvia.It is recommended that in the coming years, existing information on these areas shouldbe collected and reviewed, and possible complementary field studies carried out.Concerning rivers, the situation is better: Eurajoki and Lapinjoki are located nearby andhave been monitored from 1970 and 1972, respectively (Lehtonen, 2005b,c). Data from1992–2002 can be found in Ikonen et al. (2003). In case the relevancy of smaller riversand ditches increases in further stages of the transportation models, they should be identifiedas well. However, establishment of monitoring data will be a problem for those.Potential mire reference areas are, for example, mires close to Vuonajärvi and Kaarojärvi.The Geological Survey of Finland is continuously surveying mires and the resultsare published by municipalities. Survey reports exist from two municipalitiesneighbouring Eurajoki: Lappi (Stén & Moisanen 1996), and Eura (Toivonen 1994).Detailed analyses and mire profiles, when exist, can be ordered from GSF.The Geological Survey of Finland is preparing a report concerning the modelling of thetopographical development of Eurajoki and Lapinjoki drainage areas (Ojala et al. 2006).In the report the validity of current model has been evaluated by comparing situationsfrom year 2000, 1500, 1000 and 500 BP to other information. This report can be used toidentify lakes from a larger area with development history similar to current sea areas ofOlkiluoto.

132Figure 11-1. Potential lake and mire reference sites.

13312 CONSISTENCY AND CONFIDENCE ASSESSMENTUncertainties cannot be avoided in modelling, especially in the case of biosphere. It isthus necessary to assess and demonstrate the level of confidence in the modelling andits results. Tools for confidence assessment have been developed in SKB (e.g., SKB2004), and further applied in the Olkiluoto Site Description (Posiva 2005).The consistency and confidence assessment of this report was performed by iterativelygoing through the data, interpretations and models. This was performed using e-mailedlists of questions after an initial workshop (June 2006). In the following, land use is notexplicitly considered, since at the moment the description is not exhaustive and consistsof several incoherent pieces of data due to the priorisation of the topics within the giventime schedule. However, it has been acknowledged that more work is needed in thatsector and in the future versions of Biosphere Description the land use data could beused to explain especially regional-level variation found in the other descriptions atleast to some extent.12.1 Are all Data Considered and Understood?The method of interpretation is the key to the assessment of confidence. Treating alltypes of data and the interpretations of the different observations in a similar and unbiasedway enhances confidence (Ikonen 2006). In this section, the data used are lookedat once more, unused data are listed and their utility pondered, and data with low accuraciesare pointed out.Climate, Meteorology and Chemical depositionAll available weather observation data from the lowest levels of the nuclear powerplant’s mast have been used, but data from higher levels (>20 m from ground) havebeen omitted as irrelevant. Weather observations from forest intensive plots have notbeen used due to short time series at the moment, but it has been acknowledged thatthey would give more representative results concerning forested areas, which occupymost of the study area. For description of snow and ground frost conditions, all site datahave been used and it has been considered to be representative at least to the centralOlkiluoto Island. However, those are manual measurements with an interval of oneweek and likely capture the seasonal variation, but not the daily variation, which can belarge.For a description of chemical deposition and radionuclides in the air, all site data havebeen considered, although the integration of different data sources could be improved.The measurements and analyses can be considered to provide accurate data based onwell-established methods. One possible scenario-dependent bias concerning the biospheremodelling of the long-term is the effect of dust-producing activities that is seenin a needle wash study (Section 4.2).The description of past climate stages is based on earlier compilations in reports preparedfor Posiva and it is based on literature reviews. It is believed that the descriptionsare valid at least at larger regional or national level.

134Topography, Bathymetry and Shoreline DisplacementAll available site data have been used, supported by elevation and depth data from thenational GIS databases. However, especially with regard to the bathymetry, the dataavailable in the nautical charts is rather sparse on the areas deeper than 10 metres andnear shores. For this report, no interpolation was done for sea bottom model, but inother applications this matter should receive attention.For the description of the land uplift processes, no strictly site-specific data is available,but the work by Eronen et al. (1995) used as the basis has been targeted on the Olkiluotoregional area specifically. In shoreline displacement estimations the main data gapconcerns the paludification processes; sedimentation of organic matter is the main factorin shallow and sheltered areas but no confidently site-specific quantitative data areavailable.Overburden and Sea SedimentsAll available site-specific data have been used. However, site-specific chemical andphysical (biological) analyses are lacking from the sea sediment cores, and there is notenough confidence to apply the few generic data on the basis of the current other sitedata. It has not been possible to collect acoustic-seismic data within the islands south ofOlkiluoto, and elsewhere the distance between study lines is too wide. For interpretation,there is no consistent data from study lines that stretch from land to sea. There isno well-established data on sedimentation and erosion rates in the area either.Forests and Other Terrestrial HabitatsThere exists now plenty of data of forests at different levels (Fig. 12-1 and A-2). Theintensity of the monitoring increases from vegetation polygons used for initial mappingand description of the vegetation to FIP plots, where the functioning of forest ecosystemsis being monitored. Most of the available site-specific data have been used in thedescription of forest environment and the biomass calculations. Those left out are: Results from litterfall monitoring on the intensive-level FIP plots were not usedsince the monitoring time is short and from two types of forest habitats only. The analyses of soil microbe studies (Potila et al. 2007) were completed in late2006, and these results could not be integrated into the text due to lack of time.

135Figure 12-1. Forest monitoring levels. The numbers of monitoring plots are 560 (FET),94 (FEH), 11 (MRK), and 3 (FIP). The FEH plots are a sub-sample of the FET plotsand the FIP plots are a sub-sample of the MRK plots. The number of FET and FEHplots has been reduced due to expanding infrastructure.Terrestrial Fauna and BirdsAll site-specific data have been used in the description. There was not enough data forthe construction of a complete ecosystem model, thus a preliminary model was constructedfor moose only.Sea EcosystemAll site-specific data have been used in the description. The utility of the flad inventoryby the Southwest Finland Environment Centre was checked, but was not applicable tothis situation.12.2 Uncertainties and Potential for Alternative InterpretationThe uncertainties in description and ecosystem modelling may arise from inaccurate orsparse data, spatial or temporal variation, limited understanding of the process, etc. Ingeneral, small estimated uncertainties, and an inability to produce many different alternativeinterpretations from the same data are indicators of reasonable levels of confidence.New measurements could help in resolving the uncertainties or distinguishingbetween alternative interpretations (Ikonen 2006). In this section the main uncertaintiesare listed and the causes of uncertainties determined. New data that could potentiallyhelp in resolving the uncertainties are considered.

136Climate, Meteorology and Chemical DepositionClimate data can be considered as being reliable, with any uncertainties due mainly tomeasurement errors. The main uncertainty is due to the resulting interpretations madeand due to comparisons with the results from other sites; that has been judged to be low.Snow thickness values represent the average for the island, due to the values being averagesover an observation line of 20 single measurement points on different vegetationtypes. Ground frost has been measured similarly using from five to eleven measuringpoints, however significant differences may result depending on the soil type and atmosphericconditions at each point.The chemical deposition data from MRK plots has been collected for a short period oftime. The results from the deposition collectors and needle samples should be analysedthoroughly together in order to get a better understanding of the origins and behaviourof different elements. Attention should also be paid on the recorded activities on theconstruction sites and their possible effects to the results.In the climate change studies, both spatial and temporal scales are large and resolutionslow. The past climates of the last glacial maximum and more recent events can betraced with moderate accuracy from so-called proxy data (e.g., the markings from icesheets, tree rings, etc.) and historical records.Topography, Bathymetry and Shoreline DisplacementThe topography is now presented by 1 m and 5 m resolution grids. This might be toocoarse from the point of view of detailed combination of different types of data. However,for the purpose of this summary report it has been considered adequate. Bathymetryis presented based on the navigational charts that lack detailed data near shorelineand on areas deeper than 10 m. In the modelling for illustrating the past topographicaldevelopment, sedimentation and erosion processes are not included. Those processesmight be important especially when considering the river channels and current and formerdepressions.Overburden and Sea SedimentsThe principal uncertainties in understanding the types and origin of the overburden andsea bed can be summarised (Posiva 2005):Interpretation of acoustic/seismic surveys of seabed sedimentsInfluence of recent anthropogenic effectsDetermination of the location of sub-seabed lineaments and their correlationwith extrapolations made in the geological structure mapsVariation in overburden thickness and stratigraphyThe majority of the detailed data on the overburden are available for the central parts ofthe island, where the investigations have been focused. However, it is likely that thevariation in the stratigraphy or properties of the overburden over the whole island is

137quite minor. Despite that, it should be born in mind that it is possible that the anisotropyin the overburden sediments may influence groundwater flow, especially near the surface,resulting in the potential need for more detailed modelling in the future, after moreinformation on the overburden is obtained from the investigations.The soil samples from KK pits have not been taken by soil layers (humus, eluvial, illuvialbasal till) but by depth classes which makes the comparison difficult. It is also difficultto take different processes into account (leaching, weathering, etc.).The soil solution monitoring has experienced some technical problems at the initialisationphase. The situation is going to be improved for the summer of 2007.To reduce uncertainties, the geochemical database by Geological Survey of Finland,which contains information of till, lake sediments, stream sediments and groundwatercould be used. With help of the database estimates for whole study site could be obtainedand the Olkiluoto specific results benchmarked. These databases are based on asparse grid, but, for example, the southwest Finland clay soil data could be comparedwith other Finnish sites (sub and supra-aquatic areas). In clayish soils the concentrationsof elements are usually higher due to differing water-carrying capacity etc.Mass balance flow calculations at drainage area level could also help in reducing theuncertainties. By calculating the input and output of elements, it could be estimatedwhat kind of organic and inorganic reactions are taking place in the soil and water andconclusions could be made of the mobility of elements and compounds and the geochemicalchanges in the drainage area. It is probable that the drainage areas are going tochange in the future (recharge – discharge).Considering the characterisation of the seabed sediments, uncertainties are associatedwith underlying units containing clay-rich horizons, which result in difficulties in interpretingecho sounding surveys. In some basins, and also in the areas where the sea flooris covered by sandy/gravely lag, Ancylus Clay can be indistinguishable from other relatedsediments in such surveys. Sometimes recent mud and sub-recent mud/clay sequencesare nearly indiscernible, and are present as a transparent layer with faint stratification;the resulting structure is similar to that shown by the Litorina Clay, with whichit could be confused (Posiva 2005).Furthermore, there was no data on site-specific chemical properties of the sea sediments.A recommendation was prepared for the analyses of future sediment samples.The grain size should be analysed in order to distinguish between clay types (e.g.,Ancylus clay/sulphid clay). It would also be useful to obtain information of the age ofthe sediments. Concentrations should be measured according to the following list: Heavy metals Nutrients Radioactive materials (to complement the database summarised in Ikonen2003, Roivainen 2005, and Haapanen 2005, 2006) Organic compounds, e.g., tin compounds

138When comparing the sea sediment map with the forest soil map (polygons) it is clearthat there is a discrepancy in the data generalisation in one sector or both. It is mostlikely that the poor offshore data in sea sediment mapping has produced an overestimateof rocky areas in the sea North of Olkiluoto Island. Correspondingly it has not beenpossible to collect acoustic-seismic data within the islands south of Olkiluoto. A newsounding is recommended to be carried out in the near future, since the distance betweenstudy lines is too wide. It would also be reasonable to establish a study line thatstretches from land to sea. There is no data on erosion and sedimentation areas in thenearby waters of Olkiluoto Island, except single sedimentation rate values in (Mattila etal. 2006). The large-scale information on the sedimentation and erosion in the basin ofthe Bothnian Sea is very coarse and not found useful as such.Forests and Other Terrestrial HabitatsThe general description of the forest resources on Olkiluoto island via, for example, sitetype, age class, and tree species distributions can be considered accurate with the currentlyavailable multi-layered data. It must be remembered, however, that forest inventoryresults are always based on sampling and models: while it is easy to observe theage, diameter, height and species of one tree, deriving further variables like stem volumeand obtaining all those characteristics for one sample plot, one stand, or whole forestarea like Olkiluoto requires estimation. This is not a problem, since tools for forestinventory calculations have been developed for a long time, and are based on largeamounts of data and accumulated knowledge of the relationships of parameters. Theground vegetation coverages and species frequencies can also be considered relativelyaccurate. In the case of terrestrial vegetation, the greatest uncertainties are in the nutrientconcentrations and biomasses (or carbon) of trees and other plants. The former variableis laborious to sample and analyse, and the latter is based on a long series of models: from a few stem measurements (breast height diameter, height) to tree volume,from tree volume to total tree biomass, from biomass to carbon, and from visually analysed plant cover to plant biomass, from plant biomass to carbonA common problem is that fine roots make a considerable amount of plant biomass, butmaking estimates of their amount is very difficult. New models developed byHelmisaari et al. (2007) were used here. There are currently no proper tools for estimatingthe biomass (and consequently, carbon) of the bush layer of forests. Ground vegetationsamples, used for nutrient analyses, were taken only of those parts that are commonlyused as bioindicators, or that can be compared with reference data from otherstudies. Here, however, these nutrient results were used only in the description on thenutrient status. For carbon estimates generic values were used.The forest processes are monitored in only two plots at the moment, therefore the mostdetailed site-specific results (e.g. litterfall) cannot be considered to represent the forestsof the whole of Olkiluoto Island, and were not used here. However, these results couldbe used for benchmarking generic relationships used for the whole site.

139In Finland, a lot of generic forest inventory and monitoring data exists, which can beused to benchmark the site-specific results. This has been done when reporting foreststand parameters (FET-plots; compared with the figures of Southwest Finland ForestryCentre in Saramäki & Korhonen (2005)) and FEH plot nutrients. As well, analyses ofthe samples from the forest intensive monitoring plots (FIP) have been compared withresults from similar site types. With respect to biomass and carbon analyses, severalways to calculate the dry masses of tree components exist. Furthermore, results from afew thoroughly analysed stands in other locations in Finland can be used to validate theecosystem modelling results.There are currently no measurement plots with detailed plant cover analyses in the treelessparts of the terrestrial habitats: arable lands, shores, gardens, roadside buffers etc.The only exception are treeless mires.The mires are few and of several mire types, which means that they differ from theirnutrient status, peat accumulation rate etc. More intensive studies concern Olkiluodonjärviand some forested measurement plots only, and few general conclusions can bemade. The peatland surveys of Geological Survey of Finland could be used to obtaindata from relatively similar peatlands in nearby areas.New data that could be helpful in future assessments are: Expansion of the measurement plot network to shore vegetation. Sample trees to obtain local estimates for biomass, carbon and nutrients in stemsand twigs. Samples from all parts of the ground vegetation (below and above ground). Local measurements of carbon cycles, e.g., soil respiration. The monitoring of litter production should be extended to other forest habitatsfor future modelling purposes.FaunaOn the one hand, the basic wildlife survey data on Olkiluoto is clearly lacking temporalcontinuity, and, on the other hand there are substantial gaps in the data on specific settingsor specific taxons. Some factors causing uncertainty are listed below:The fauna assessments are based on a somewhat limited number of local wildlifesurveys. Estimates of the numbers of small and medium-sized mammals arerelatively uncertain.There is not any fixed follow up series regarding terrestrial wildlife on the island,nor systematic comparisons between Olkiluoto and ecologically similarneighbouring areas.Variation within and between years makes the estimates of the contribution offauna to the terrestrial pools and flows difficult.No valid research on amphibians or reptiles has been made on the Olkiluoto Island.There only study on insects small in scale and short in duration.There has been no research on the effect of the Olkiluoto plant cooling waters towaterfowl and seabirds.

140Only via thorough and methodical survey programme is one able to rule out the between-yearvariations, enhance the accuracy of assessments and finally develop consistentmodels. A fair example of a proper scrutiny particularly in the case of birds andmammals can be found from SKB's studies. Annual surveys have been performed in thevicinity of nuclear power plants Forsmark and Oskarshamn between 2001 and 2005(e.g., Truvé & Cederlund 2005, Green 2005, 2006).To improve the data basis, the following actions are recommended as a coherent campaignto be further developed into effective monitoring: Mapping and classification of habitats concerning fauna. Literature study of weights, concentrations, production and consumption by species. Systematic survey on the abundance of mammals and birds on the island. Basic research on the insects on the island. Basic research on the status of reptiles and amphibians on the island. Systematic comparison between Olkiluoto and ecologically similar neighbouringreference areas, attention should be paid, for example, on the effects of theinfrastructure on terrestrial fauna, and the effects of thermal effluent on waterfowland marine mammals.For better site understanding, the effects of thermal effluent on waterfowl, seabirds andmarine mammals, and also the actual significance of mortality increase due to powerlines could also be examined more thoroughly, even though this is not relevant for thepost-closure safety of the repository.Carbon Cycle in Terrestrial EnvironmentThe carbon cycle is quite well understood but there still remain many uncertainties(Liski 1997, Monni et al. 2004, 2006, Peltoniemi 2005):Stock changes are difficult to measureMeasurements are laborious and expensiveHigh spatial variationDynamic character of the stocksDecomposition processes in soils are complexOrganic matter consists of innumerable amount of different compounds andcompound groupsWide range of fast and slow processesSystem boundariesSea EnvironmentConcerning the sea environment, the temporal continuity is good, but some data isclearly lacking. The sparse network of measuring points makes current sea results byfuture lake areas only indicative.

141The effects of the Olkiluoto nuclear power station on the state of the surrounding seaarea are studied with the help of physico-chemical and biological variables. The chemicalvariables include nitrogen, pH, conductivity and nutrient concentrations. The monitoringdoes not include determination of organic carbon, which is a key variable forecosystem modelling.The biological variables include phytoplankton, bottom fauna, fish stocks and aquaticflora. The species and biomass of phytoplankton are studied at the observation siteSEA08 (Target area 3a) six times during the open-water season. Samples are also takenfrom all the other observation sites at all sampling times, but these are combined toform a composite sample for the open-water season. The seasonal distribution of phytoplanktonshould be studied at more than just one sampling site to establish in more detailthe differences between the cooling water discharge area and other parts of the seaarea. The monitoring activities also lack one integral part of the food chain, i.e. thezooplankton that feeds on the phytoplankton and serves as a source of food for fish.Furthermore, fish stocks have not been studied from the point of view of the ecosystem,but from that of fisheries.The load coming into the sea area is known relatively well, with the exception of theamounts of substances leaching from the near-catchment. Monitoring of the wetdeposition has been started in the terrain environment. There was a considerabledifference between the site-specific deposition results and the generic results. Since thequality of bottom sediments is poorly studied, the potential release of the nutrients fromsediments to water is not known.Reports found on the modelling of flow conditions in the waters near Olkiluoto arefocused on the needs of the nuclear power plant (Koponen et al. 1995, Koponen &Ylinen 1999) or the development of Rauma harbour relatively far south from the site(Koponen et al. 1998) and are not descriptive in the terms of flow conditions overall inthe region. Thus the transport of suspended solids and nutrients is not known.The following recommendations were given to reduce the uncertainties: Organic carbon should be added to the analyses. The seasonal distribution of phytoplankton should be studied at more than justone sampling sites to establish in more detail the differences between thecooling water discharge area and the other parts of the sea area. Studies on the species and amount of zooplankton should be started so as tohave a more detailed picture of the structure and functioning of the ecosystem. The structure and amounts of fish stocks should be studied in more detail bymeans of test fishing and seine-fishing of fry. The volume and quality of runoff waters from nearby catchments should bemonitored in the area during different seasons for perhaps two to three years. The results of atmospheric deposition measurements should be complementedby placing some deposition collectors near the coastline and on islands andislets.

142The flow condition models should be retrieved, if possible, or newcorresponding models established and quantitative analyses should be done forthe area far enough around Olkiluoto.The study of the nutrient fractions in sediment should be implemented in orderto estimate the importance of the nutrient release from the sediment.12.3 Consistency Between Different DisciplinesDuring the initial workshop in June the following interaction matrix was constructed(Fig. 12-2) that illustrates the connections judged important to include in the integratedbiosphere description and interpretations of data. At present, most of these are consideredat least implicitly, but more effort to the integration is clearly needed both in thefuture versions of this report and within the environmental monitoring programmes. Inthis matrix, land use is omitted, but it is an important factor to be considered especiallyfor habitats of fauna.0 1 2 3 40 Climate Deposition Deposition, climateClimate, part of habitatDeposition, climate,resuspension ofsediments1Sea/land distribution,(soil respiration)Overburden (incl.soil water, groundwater)both terrestrialand aquaticSoil type, groundwater/moisture conditions,nutrients etc.,organic matter content,microbesHabitat, (land use)Sediment type, nutrientsetc, runoff,erosion, sedimentation,resuspension2 EvapotranspirationMicrobes, litterfall,throughfall, regulationof conditionsTerrestrial vegetationHabitat (food supply)Littoral zone3Bioturbation, excretionEatingTerrestrial and avianfaunaMoving between,(food supply)Bioturbation, erosion,4Sea/land distribution, sedimentation, bottomevaporation, sea spray vegetation/fauna, seaLittoral zone, seasprayMoving between,(food supply)Aquatic (fauna/flora,water)spray0 1 2 3 4Figure 12-2. Interaction matrix for biosphere assessment.

14312.4 Overall JudgementThe overall view of the presented sector by sector analyses is presented here. Out of thesectors of current biosphere presented in this report, the terrestrial vegetation onOlkiluoto Island has been measured with the greatest extent and intensity. However, thedeeper in detail in the processes we go, the less is known: the Forest Intensive MonitoringPlots produce data of the cycling of matter and nutrients, but they cover currentlyonly two habitat types and the time series are short. Relatively lot is known also of theoverburden, but due to the more laborious measurements and disturbance to the studyobject, the spatial coverage can never be as good as with terrestrial vegetation. The temporalcoverage is about the same as with vegetation, but the soil profiles and chemicalconcentrations tell more on the historical development than in the case of vegetation.The terrestrial fauna is currently described only with the few site-specific data, andsome groups have not been inventoried at all. The temporal coverage is best in the caseof sea ecosystems, but there the spatial coverage is poor and the uncertainties large.The report concentrates on the current biosphere of Olkiluoto, which will be only asmall part of the future area of interest, and the importance of the sea areas of present,gradually transforming to limnic and terrestrial systems due to the land uplift, will increasefrom the point of view of the Safety Case. The vegetation of current Olkiluotowill also gradually change in the future as the land up-lift proceeds. Current OlkiluotoIsland is, however, the best reference to the nearby future terrestrial areas, and knowingits soil, soil/vegetation interactions and the phases of the vegetation succession will mirrorthe future processes. Furthermore, the description of current Olkiluoto servesevaluations of the environmental impact.The analysis results of each sector have generally been benchmarked with referencedata in other parts of southern Finland. In few cases the results from Olkiluoto weredifferent from the reference sites but it was not yet clear whether this was due to itscoastal location or the fact that it is the site of major construction works and large-scalepower production. More emphasis should be put on discussing this question in the futurefield inventory reports (as it has already been done in many cases), based on theexisting literature and the expert knowledge of the authors.All site-specific data have at least been considered of in this report, most of them havealso been used and summarised. Some first time monitoring studies, such as the soilsurvey and mapping of vegetation nutrition by FEH plot network (Tamminen et al.2007), have been accomplished since the Baseline and Site Description reports (Posiva2003, Posiva 2005), but no results contradictory to the previous have been obtained.Results presented in this report have been preliminary benchmarked across the disciplines.Generally, the results were consistent in this sense. The largest disagreementsnoticed were between the soil survey on the island and the acoustic-seismic sea sedimentinventory. There is also a difference in the regional deposition results and the sitespecificwet deposition results, but these may be issues of measured quantities and spatialvariations.

144Many recommendations for further work have been presented in this chapter. A comparisonof their feasibility and importance is shown in Table 12-1. The gaps in somesectors can be covered by generic data and thus improved with a literature study andpossibly further consolidated by just a benchmarking study at the site. In this report, thelimits set by the modelling approaches were not taken into account, but the aim was todescribe the current biosphere as it is. However, before launching any newmeasurements, the requirements of the Safety Case and monitoring of environmentalimpacts must be considered carefully together with priorising within the overall RTDprogramme.Table 12-1. Evaluation of the recommendations of new measurements or studies givenfor each sector.Domain and recommendationEvaluationClimate, meteorology and chemical depositionResults from the deposition collectors and needleanalyses should be analysed together andcompared with recorded activities on theconstruction sites.Overburden and sea sedimentsObtain till, lake sediment, stream sediment andgroundwater data from the geochemical databaseof GSF.Construct mass balances at drainage area level.Sea sediments should be sampled and analysed forgrain size, age, and elemental concentrations.Carry out a new, more detailed sounding of seabottom.Establish a study line that stretches from land tosea.Why: to get a better understanding ofthe origins and behaviour of elements.Importance: highFeasibility: highWhy: to get estimates for whole studysite and to benchmark the Olkiluotospecific results.Importance: moderateFeasibility: highWhy: to reduce the uncertainties in soilparameters, to find out the organic andinorganic reactions in soil and water,and further to make conclusions of themobility of elements and compoundsand the geochemical changes.Importance: highFeasibility: low to moderate (on the flatterrain exact delineation of the drainageareas and the lack of distinctive ditchesmake an exhaustive study challenging)Why: to obtain knowledge of futureoverburden, and current nutrient releasefrom the sediment to sea water.Importance: highFeasibility: moderateWhy: to get better coverage and todissolve the discrepancy between seasediments and overburden.Importance: highFeasibility: highWhy: to dissolve the discrepancybetween sea sediments andoverburden, and to obtain knowledge ofthe processes during land up-liftImportance: highFeasibility: high

145Table 12-2 cont'd. Evaluation of the recommendations of new measurements or studiesgiven for each sector.Terrestrial vegetationExpand FEH plot network to shore vegetation.Sample some trees for biomass, carbon and nutrientsin stems and twigs.Samples from all parts of the ground vegetation(below and above ground).Local measurements concerning carbon cycles,e.g. soil respiration.Terrestrial faunaMapping and classification of fauna habitatsLiterature study of weights, concentrations, productionand consumption by species.Systematic survey on the abundance of mammalsand birds on the island, completed with comparisonbetween Olkiluoto and ecologically similarneighbouring reference areasBasic research on the status of insects, reptiles andamphibians on the island.Why: to obtain species lists, frequenciesand coverages of shore vegetationImportance: moderateFeasibility: highWhy: to obtain local estimates or calibrationdata for generic modelsImportance: moderateFeasibility: moderateWhy: to get more accurate data on nutrientconcentrationsImportance: moderateFeasibility: moderateWhy: to get more accurate ecosystemmodelImportance: moderateFeasibility: moderateWhy: to be able to calculate fauna biomasses,production, and consumptionby area units and further quantify theecosystem models.Importance: highFeasibility: moderateWhy: to be able to further quantify theecosystem models.Importance: highFeasibility: highWhy: to be able to get more accurateestimates of current situation, and furtherquantify the ecosystem models.Importance: highFeasibility: moderateWhy: to be able to establish basic conditionsand further quantify the ecosystemmodels.Importance: highFeasibility: moderate

146Table 12-2 cont'd. Evaluation of the recommendations of new measurements or studiesgiven for each sector.Sea ecosystemsAdd organic C to monitoring program.Add more locations to monitor phytoplankton distribution.Start studies on zooplankton.Study structure and amounts of fish stocks in moredetail by means of test fishing and seine-fishing offry.Monitor the volume and quality of runoff watersfrom nearby catchments during different seasonsfor 2–3 years.Extend the deposition collector network to thecoastline and on islands and islets.Establish flow condition models in nearby seaareas.Why: to get site specific knowledge ofcarbon cycling.Importance: highFeasibility: highWhy: to establish the differencesbetween the cooling water dischargearea and the other parts of the sea area.Importance: moderateFeasibility: moderateWhy: to have a more detailed picture ofthe structure and functioning of theecosystem.Importance: moderateFeasibility: moderateWhy: to get data for ecosystem modelling.Importance: highFeasibility: lowWhy: to get site specific data of nutrientload to sea.Importance: highFeasibility: moderateWhy: to get site-specific data of seadeposition.Importance: moderateFeasibility: moderateWhy: to get site-specific knowledge ofthe transport of suspended solids andnutrients.Importance: moderateFeasibility: moderate

14713 CONCLUDING REMARKSThis report describes the biosphere of Olkiluoto Island. The principal area of interest isthe main island of Olkiluoto and surrounding sea regions, where the environmentalstudies have been concentrated. The sea was further divided into basins where lakes willprobably form in future. Some statistics are presented also for a larger area aroundOlkiluoto Island. Temporally this report concentrates on the current biosphere, butconcerns also the historical development and future until the emplacement of the firstspent nuclear fuel disposal canister in 2020.Although some of the nuclear power production related monitoring studies withinTVO's (the power company) programme have been going on from the 1970s, therepository-related environmental monitoring of the Olkiluoto Island has only recentlybeen comprehensive. Consequently, this is the first report summarising the descriptionsof the present biosphere conditions at Olkiluoto thoroughly. According to the mainschedule, the next report is planned to be compiled in 2008/09 followed by a thirdreport in 2011 (Ikonen 2006).Due to the timing of this report at a relatively early point compared with the datacollection and analyses, the main emphasis is on description. The construction andfurther quantification of the ecosystem models was also started here, but must be morethoroughly addressed in the next report. The writing process strengthened theinteraction between the different sectors of the environmental monitoring programme.Before this report, the studies concerning biosphere had been summarised in theBaseline Conditions report (Posiva 2003) and the Site Description report (Posiva 2005).In the following, a brief summary of this work is given sector by sector.Land UseThere have been great changes in the land use in recent years. These have been due tothe construction of the third nuclear power unit (OL3), the overall expansion of thenuclear power production infrastructure, the excavation of the undergroundcharacterisation facility ONKALO and denser ground surface-based site investigationsfor the spent fuel repository.Climate, Meteorology and Chemical DepositionOlkiluoto Island belongs to the continental climate zone, with some local marine influencedue to its location on the eastern coast of the Bothnian Sea. In the spring time, thepresence of the sea lowers temperatures somewhat compared with those inland. In theautumn, the sea provides warmth, so that night frosts are less frequent than in themainland. The snow cover, being less than 20 cm, is usually thinner than at the closestreference sites. The frost layer has been at a depth of 10…70 cm. The duration of thegrowing season has been 180 days on average in recent years.

148The ongoing construction works and the dense network of roads contribute to the recentchemical deposition results: the pH was higher in 2005 compared with 2004, beingslightly above the national level and the concentrations of base cations (Ca, Mg, K andNa), which also contribute to the pH values, were very high compared with the overallsituation in Finland. The pH, NH 4and NO 3values were lower within the forest standsthan in the open areas, which is typical for coniferous stands. The relatively high depositionof Cl with associated Na is due to the proximity of the sea.TopographyThe Olkiluoto Island is characterised by flat topography, with the highest point at 18 mabove mean sea level. The depth of the bedrock surface is variable, but the depressionsare filled with thicker layer of till and the outcrops stick through the modest soil layers.The waters around Olkiluoto are generally shallow and the sea area is relatively open,thus the winds clearly affect the water currents. The current apparent land up-lift rate is6 mm/year.Overburden and Seabed SedimentsSoils at Olkiluoto are weakly developed due to short time span; they emerged from thesea about 500 to 2000 years ago. The overburden is mainly fine-textured till. Mostcommon soil types at Olkiluoto are weakly developed (often podzolised) coarse tomedium coarse Arenosols or fine-textured Regosols, shallow Leptosols and Gleysolscharacterised by shallow groundwater. There is a quite considerable amount of stones,boulders and exposed bedrock. Organic layer on mineral soil sites was classified inmost cases as mor, peat or mull-like peat.The area of mires is minor; the few small-sized mires are young and they have thin peatlayer, ca. 20–50 cm. However, more mires will develop from the easily paludified areasat the current shorelines, especially if covered by clay. The soil water analysis resultsreflect the young age of soils and proximity of the sea, for example, high concentrationsof Cl and Na.Soils at Olkiluoto are on average acid, except for the alder stands growing nearseashores, which are much less acid due to more clayish soils. There are moreexchangeable calcium, magnesium and sodium in the surface soil at Olkiluoto than onthe control plots in southern Finland. Concentrations of base cations, especiallycalcium, correlate with the forest site type. Mineral soil sites have higher nitrogenconcentration and lower C/N ratio than average Finnish forest soils, meaning higher soilfertility. Peat nitrogen concentration and peat C/N ratios indicate satisfactory nitrogenmineralisation conditions. Nitrogen concentration increase and C/N ratio decrease frompoor sites to more fertile site types. All elements, except for Mn, appeared to havehigher concentrations at the Olkiluoto mineral soil sites than at the control plots.

149The seabed sediment inventories indicate that there are 30–40% of till, 30–40% of outcropsand the rest mainly Ancylus clay. No data exists at the moment for the chemicalor physical composition of these sediments.Terrestrial VegetationThe number of results concerning terrestrial vegetation has increased considerably sincethe start of monitoring in 2002. The results show that outside the industrial areas, thenature of Olkiluoto resembles that of other coastal regions in southwest Finland.Commercial forests cover most of the Olkiluoto Island. They grow on more fertile sitesthan on average in southwest Finland, but contain also rock outcrops. The forests havelower mean volume and grow faster than in southwest Finland, respectively, becausethey are younger due to the intensive forestry. Spruce accounts for 40% of the volume.The significant areas of natural vegetation are the Liiklanperä old-growth forest area,the Ulkopää-Tyrniemi area, and the shoreline, which supports herb-rich alder stands innatural condition. The vegetation of coniferous forests resembles that of reference sites.There is plenty of dead wood in the Liiklanperä conservation area, a sign of highbiodiversity.Mires are few, mostly drained and represent a wide range of treeless and forested miretypes. The power line from the NPP stretches across the island and its vegetation ischaracterised by bushes and bush-like trees.The macronutrient concentrations in vascular species are relatively similar to the concentrationsmeasured in southern Finland. Vascular plants have lower heavy metal concentrationsthan bryophytes, which have accumulated especially Cu, Ni and Fe from theemissions caused by soil construction and industrial activities. The foliage analysis indicatesthat the tree stands generally have a good nutrient status on Olkiluoto.Trees account for most of the vegetation biomass and carbon. There was on average 7.3kg/m 2 of terrestrial vegetation biomass in forests.Terrestrial FaunaRegarding wildlife species, Olkiluoto Island is a typical representative of coastal forestareas of southwestern Finland. As elsewhere in the forested areas of southern Finlandalso on the Olkiluoto Island the commercial forestry is the single most significant factoraffecting the current wildlife. Nuclear power production and related activities havevarious wildlife effects on the island, but the only actual effect that is characteristicparticularly to the nuclear power production is the local impact of the cooling waterdischarge. The number of bird species is relatively high; northern seashore of the islandis the most valuable waterfowl habitat. Mammalian fauna on the island is similar to thatin the surrounding areas in the mainland. Olkiluoto Island is presumably not importantfor the occurrence of rare species of wildlife. Data of mammals and birds should besupplemented to get a more coherent picture, while data of reptiles, amphibians andinsects is yet lacking.

150Seawater QualityThe water quality in the Olkiluoto offshore is quite typical of the coastal waters of theBothnian Sea although the increased eutrophication is observed locally due to nutrientleach, local wastewater loads, and discharge of cooling waters from the nuclear powerplant. The eutrophic waters flowing from south (Haapasaarenvesi, Rauma) have likelyan impact on the sea area of Olkiluoto. The state of Eurajoensalmi is mainly determinedby the waters brought by the Eurajoki river. The general state of the Bothnian Sea andespecially the substances carried from the mainland (land use) by the rivers and ditchesaffect the water quality and biological production.The cooling waters typically keep the nearby waters unfrozen during the winters in anarea of 3–20 km 2 . In the discharge area the water temperature is 5–7 degrees higher inthe surface layer, and 1-1.5 degrees higher in the deeper layers than in reference areas.During the open water season the differences are smaller and more local. The highertemperature conditions generally increase fish stocks and primary production.The P and N concentrations during the open water season increased until the early2000s in the discharge area. The vertical variation is quite small, but there are higherconcentrations of P and N in the bottom-near water than in other water layers.Marine Flora and FaunaChlorophyll-a, phytoplankton biomasses, primary production in situ and primaryproduction capacity all showed increased production and eutrophy in the 1990s. Thetotal amount of blue-green algae has mainly been small, but during many years therehas been a higher amount in the cooling water intake and discharge areas. The sea floraat the nearby waters of Olkiluoto ranges from algae dominant communities (hardbottoms) to the vascular plant dominant communities (soft bottoms). The effects ofeutrophication can be seen in the area affected by the cooling water.Earlier, the lack of oxygen and the deterioration of the state of the bottom causedchanges in the species composition of bottom fauna and the diversity of species wasreduced and their biomass collapsed. In recent years, better oxygen conditions havebeen reflected in the recovery of bottom fauna communities.The most common fish species are perch and roach. Economically the most importantare perch and pikeperch, followed by pike, roach and Baltic herring. The catch ofsalmon and trout has increased. The cooling waters have an effect of increasing the fishstocks. During the winter months, trout and whitefish have been found in the unfrozenwater area caused by the cooling water.Limnic EcosystemsLimnic ecosytems are currently few on Olkiluoto Island and in its vicinity. There are nonatural lakes on the island. Thus, relevant limnic ecosystems in the surrounding areaswere identified for reference use. Concerning rivers, the situation is different.

151The closest rivers are Eurajoki and Lapinjoki. The watershed of Eurajoki is 1,336 km 2 ,and its lake percentage is 13%. At its upper course Eurajoki is classified as good orsatisfactory in terms of general usability. The middle part of the river is classified aspassable, and the lower part of the Eurajoki river has mainly been satisfactory. Between2000 and 2005, the Eurajoki river carried on average 19.6 tonnes of phosphorus and 619tonnes of nitrogen into the sea annually, originating from agriculture, point sources, andnatural leaching. The Lapinjoki river (watershed 462 km 2 ) has its origins in forest andpeatland areas. The water is brown and rich in humus and contains high levels of ironand organic matter. The general usability of the river is mostly classified as satisfactory.The substance discharges in the Lapinjoki river are mainly caused by diffuse loading. Inthe period 1990–2002, the Lapinjoki river carried on average 5.3 tonnes of phosphorusand 230 tonnes of nitrogen into the sea annually.Confidence and Consistency AssessmentThe confidence and consistency assessment was based on question lists that werecirculated during the writing process. This report focused on describing the biosphere.The qualification and quantification of ecosystem models had just started. Points thatwere emphasised in the confidence and consistency assessment due to the nature of thisreport were Listing applied and available data Listing data types where accuracy is low Listing the main uncertainties and determining their causes Determining unused data that could be used to reduce uncertainty Deciding what new data could be used to reduce uncertainty Overall judgementConcerning most sectors, central parts of Olkiluoto Island have now been studiedintensively. Data from different areas can be used to benchmark each other’s results, forexample, forest inventories vs. soil sampling. Some data sectors are, however, stilltemporally or spatially sparse (e.g., functioning of forest ecosystems) or data is lacking(e.g., some animal groups).The results in this report are based on an abundant amount of measurements andanalyses. Next, more consideration should be put on the interaction between thedisciplines and fine-tuning of the qualitative and quantitative ecosystem models.

152

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APPENDIX A: MEASUREMENT LOCATIONS171Figure A-1. Overburden monitoring sites.

Figure A-2. Terrestrial vegetation monitoring sites.172

Figure A-3. Aquatic monitoring sites.173

174Figure A-4. Acoustic-seismic sea bottom soundings.

175Figure A-5. Reference areas mentioned in the text. Note that both deposition and soilsolution are being monitored in Tammela reference point. Base map: US National Imageryand Mapping Agency (NIMA) Vector Map (VMap) Level 0, obtained fromhttp://gis.ekoi.lt/gis/index.php on Jan 24, 2007.