Martyna A. RZĘTAŁA
University of Silesia, Faculty of Earth Sciences, Bedzinska 60, 41-200 Sosnowiec, Poland, mrz@ultra.cto.us.edu.pl

BASIC COMPONENTS AND TRACE ELEMENTS IN SEDIMENTS IN THE INACTIVE CHANNEL OF THE DUNAJEC RIVER (PIENINY MTS.) AND THEIR GEO-ECOLOGICAL SIGNIFICANCE

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Geochemical tests of sediments were conducted in isolated water bodies in the river channel located in the Szczawnica reach of the inactive branch of the Dunajec River in the Pieniny Mountains. Basic composition and contents of trace elements as indicators of anthropogenic pollution were deter-mined. It was found that the components included in the basic composition of the sediments examined exhibited typical quantitative variation in their average amounts (SiO2 – 57.02%, loss on ignition – 11.72%, Al2O3 – 14.17%, Fe2O3 – 5.74%, CaO – 4.83%, K2O – 2.46%, MgO – 2.05% and Na2O – 1.13%, TiO2 – 0.87%, P2O5 – 0.18%, MnO – 0.11%, S – 0.25%), showing little variability when individual sam-ples were compared. It was found that the content of trace elements in sediments of the inactive branch of the Dunajec River channel meets the geochemical background criteria in the case of Ag, Be, Cd, Hg and is slightly higher than the geochemical background in the case of Pb and Zn while for As, Ba, Co, Cr, Cu, Ni, S, Sr and V the geochemical background is exceeded a few times (As, Ba, Co, Cu, S, Sr), around a dozen times (Ni and V) or several dozen times (Cr); for many elements, the comparison to the geochemi-cal background was not made for the lack of data. The geoaccumulation index (Igeo) indicates that the sed-iments are uncontaminated, moderately contaminated or heavily contaminated with some elements. The contamination factor indicates moderate sediment contamination with arsenic and chromium while Hg, PCBs, Pb, Cd, Cu and Zn are absent. The degree of sediment contamination (Cd=5.2) is low. The content of some trace elements found in sediments of the inactive channel of the Dunajec River branch is higher than the ranges in which these elements are found in the aquatic sediments of the hydrologically active channel of the same river. The enrichment ratio of sediments in the inactive river channel with re-spect to microelements ranges from unity (Zn, Pb) to around a dozen – Cu (IAP = 2.7), Co (IAP = 3.0), As and Sr (IAP = 3.2), Ni (IAP = 3.7), Ba (IAP = 6.8), Cr (IAP = 7.6), S (IAP = 9.6) and V (IAP = 11.6). Sediments in inactive river channels (oxbow lakes) contain a wealth of geoenvironmental information whose signifi-cance is completely different from that which can be read from sediments in hydrologically active river channels.