Section âGroundwater in Sedimentary Basinsâ - Latvijas UniversitÄte

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In order to identify sample spoiling during storage due to freezing or aerationwhich can result in calcium carbonate precipitation, the results need to be checkedfor consistency of concentration of Ca 2+ and HCO 3-ion concentrations in (mgekv/l).If the changes are severe and correlate for both ions, then the results should beconsidered as a bad mistake. It’s possible that TVC won’t spot this deviation(Fig. 2. and 3.).Fig. 2. TVC value of monitoring well No. 1492 at Inčukalns. Only one bad measurementcan be identified using TVC.Fig. 3. Cl - , HCO 3-and Ca 2+ concentration (mg/L) at monitoring well No. 1492 at Inčukalns.Two coherent drops in the Ca2+ and HCO3- concentrations suggest that CaCO3 precipitatedfrom the sample during the storage possibly due to sample freezing or loss of CO 2gas.We speculate that the proportion of incorrect analyses in the data base are similarfor the monitoring wells where long term series of observations are available andother well types where only one or a few groundwater samples have been collectedand analysed. If this is so, the overall quality of the groundwater composition database can be quantified and considered when performing statistical or individualanalyses of water composition data.References1. Mokrik, R., Mazeika, J. 2002. Palaeohydrogeological reconstruction of groundwaterrecharge during Late Weichselian in the Baltic basin. Geologija, 39, 49-572. Ingebritsen, S. E., Sanford, W. E., Neuzil, C. E. 2008. Groundwater in geologic processes,2nd ed. Cambridge. Cambridge University Press, 5363. Levina, N., Levins, I. 2005. Pazemes ūdeņu pamatmonitorings, 2004, Rīga. Latvijas Vides,ģeoloģijas un meteoroloģijas aģentūra, 345Session of Geology – Section “Groundwater in Sedimentary Basins” 31
TRACE ELEMENTS IN GROUNDWATER IN LATVIA:EXISTING DATA AND FIRST NEW RESULTSInga RETIĶE, Andis KALVĀNS, Aija DĒLIŅA, Alise BABRE,Baiba RAGA, Eleonora PĒRKONEUniversity of Latvia, Faculty of Geography and Earth Sciences, e-mail: inga.retike@gmail.comThe territory of Latvia is a part of the Baltic Artesian (Sedimentary) Basin whichcan be subdivided into three major water exchange zones: freshwater (active waterexchange), saline (delayed exchange), and brine (stagnant) hydrogeological zones,in considering the water chemistry and intensity of water connection betweenaquifers. The occurrence of trace elements in groundwater can be due to naturalsources such as dilution of water bearing rocks, surface impact or anthropogenicinfluence.An extensive set of data about groundwater in Latvia is available from thebeginning of the 1960’s and contains mainly information about groundwaterlevels, major ion chemistry and physical parameters. It is impossible to test thequality of the old data on trace element concentration from geological mapping andhydrogeological exploration during Soviet times. The more recent studies containmainly data about the Quaternary sedimentary aquifer and are limited to the activewater exchange zone. A lack of available trace element data in the deeper strata ledto the implementation of this study.The aim of this study is to determine the distribution and sources of traceelements in groundwater in Latvia and compare the results with the major ionchemistry data and WHO and EU potable water standards. At the end of this studythere will be new data about approximately two hundred groundwater samples.Groundwater samples from monitoring and supply wells, as well as boreholes andsprings, were analyzed by total x-ray fluorescence (TXRF) and atomic absorptionspectroscopy (AAS) techniques to determine the concentration of trace and somemajor elements. The contents of cations and anions, pH, electrical conductivity(EC), redox potential (ORP), TDS and dissolved oxygen were analysed to assessthe quality of groundwater.Generally, the concentration of trace elements in uncontaminated shallowgroundwater samples is bellow WHO and EU potable water standards. Previousstudies suggest that uranium, arsenic, cobalt, and copper in groundwater can oftenbe derived from agricultural fertilizers and due to the high flux of nitrate presentin infiltrating water, some metals can be released from deposits (Gosk et al.,2006). The influence of the lithology of aquifer deposits on concentrations of traceelements is statistically significant only in cases where aquifer deposits are richin organic matter or contain well-soluble minerals. Some exceeding trace elementconcentrations are associated with gypsum dissolution in shallow groundwater32 The 70 th Scientific Conference of the University of Latvia
Page 1 and 2: The 70 th Scientific Conference of
Page 4 and 5: CONTENTSRein VaikmäeThe state of a
Page 6: THE STATE OF ART AND NEW TRENDSIN T
Page 10 and 11: There are a number of boreholes pen
Page 12 and 13: • The principal parameters of the
Page 14 and 15: • For aquifers, along the borderl
Page 16 and 17: were perturbed and the sensitivity
Page 18 and 19: Fig. Geological occurrence of the U
Page 20 and 21: WATER FILLED UNDERGROUND OIL SHALE
Page 22 and 23: If we use underground water pool wa
Page 24 and 25: compiled if groundwater level monit
Page 26 and 27: 2-It was discovered that the source
Page 28 and 29: If we assume that the model was bui
Page 30 and 31: But there is more: the absolute con
Page 34 and 35: samples. Studies show that the conc
Page 36 and 37: The groundwater extraction trend in
Page 38 and 39: ENVIRONMENTAL SITUATION IN THE AREA
Page 40 and 41: Otaņķi. The first two experimenta
Page 42 and 43: Fig. 1. Sites of new samples for CF
Page 44 and 45: amount increased continuously. The
Page 46 and 47: BAB V1 GEOMETRICAL MODEL:INTEGRATIN
Page 48 and 49: THE SENSIBILITY ANALYSIS OF CL - AN
Page 50: INVESTING IN YOUR FUTUREThe session

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Section âGroundwater in Sedimentary Basinsâ - Latvijas UniversitÄte