RD&D-Programme 2004 - SKB

• Further refinement of today’s wetland models.
• Studies of the hydrology of mires and wetlands.
Data will primarily be generated by the site investigations.
20.7 Aquatic ecosystems
Knowledge concerning the dominant transport processes in the aquatic ecosystems – i.e.
running water, lake and sea – are relatively good /20-63/. The most important work with
regard to these environments is to use and develop models and modelling tools that can handle
the knowledge and to gather data from the sites in order to parameterize the models. Model
development and transport processes are described in previous paragraphs, and data from the
site investigation is described in section 20.11.
In many potential discharge areas, the radionuclides will pass a sediment layer. In this way, the
sediments in the sea, rivers and lakes will at least potentially exercise a strong influence on the
transport of radionuclides to biota. The permeability and adsorption of the sediment affect the
pattern of dispersal and dilution. A marked change in redox conditions, salinity and biological
activity takes place in the boundary layer between sediment and water, which can influence
the radionuclide flow. In the short term, these processes will probably reduce radionuclide
discharge and result in lower doses. In the long term, however, radionuclides can accumulate,
only to be released later due to land uplift, resuspension and the like, resulting in higher doses.
Furthermore, the organisms that live in sediments are exposed to elevated levels, which can
then be passed on in the food chains, for example via fish to man.
Conclusions in RD&D 2001 and its review
See section 20.2.
Newfound knowledge since RD&D 2001
A project at the Department of Limnology at Uppsala University has studied Eckarfjärden
in Forsmark for the past few years /20-26, 20-27, 20-64 to 20-66/. Many interesting results
show how the internationally and nationally unusual oligotrophic hardwater lakes work. An
initial systems ecology model of Eckarfjärden has been constructed, and results with a bearing
on radionuclide transport will be evaluated. The work has provided guidance on how other
lakes in the area should be investigated in the site investigations /20-67 to 20-69/, see below.
The measurements of above all water chemistry in the site investigation programme /20-25/
have provided not only data for the models, but also valuable information on process rates
and seasonal dynamics. The mapping and characterization of lakes in the site investigation
programme /20-70/ has furthermore provided a perspective on how commonly occurring these
lakes are. The limnology department has published its work in international journals /20-65,
20-71/ during the period and also disseminated the information to e.g. the Swedish
Environmental Protection Agency /20-72/ and other forums /20-73/.
The systems ecology models have been further refined in a doctoral project at the Department
of Systems Ecology at Stockholm University, see section 20.4 /20-17/. Field studies concerning
the importance of bioturbation (stirring caused by animals) in Baltic Sea sediments and how it
affects radionuclide cycling have also been conducted /20-42/.
A database of investigations and results from marine inventories of flora and fauna on shallow
bottoms over the past 30 years has been compiled /20-74/ in order to be able to compare sitespecific
data to national data. The work will be supplemented by a compilation of data from the
Kalmarsund area. The site investigations in Oskarshamn have examined fauna and flora on the
bottoms around the Simpevarp Peninsula /20-75/.
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