ARTICLE Geochemical characteristics of sediments from a reservoir (tank) ecosystem in Sri Lanka Rohana Chandrajith Kushani Mahatantila H. A. H. Jayasena H. J. Tobschall Received: 15 August 2007 / Accepted: 18 January 2008 Ó Springer-Verlag 2008 Abstract Major, trace and selected high field strength element geochemistry of fresh-water sediments from the Malagane tank, Deduru Oya basin, Sri Lanka, has been investigated in this study. Sediment samples were collected from 13 locations and analyzed for their elemental distri- bution using the X-ray fluorescence technique. The sediments were characterized by relatively low organic matter, ranging from 4.8 to 16.9%. The elemental distri- butions were compared with those of the average upper continental curst, and it was found that, with a few exceptions, most of the studied elements are either com- parable or depleted. Correlation and principal component analyses were applied to identify the relationships among studied elements. Major elements, most trace and light rare earth elemental distribution show strong positive correla- tion with Al 2 O 3 and TiO 2 , which indicate that the phyllosilicates and heavy minerals in the sediments are the probable hosts for these elements. The results also indicate that the sediments in the Malagane tank are representative of the materials from the metamorphic rocks in the watershed and were subjected to changes within the tank ecosystem. The results obtained from this study are vital for future pollution management of tank ecosystems in Sri Lanka, since information on elemental distribution within the sediments of tank ecosystem is lacking. Keywords Tank sediments Á High field strength elements Á Intermediate climatic zone Á Principal component analysis Á Enrichment factors Introduction Aquatic ecosystems have received significant amounts of contaminants recently due to rapid industrial growth and urbanization. Once released into the aquatic system, con- taminants are transferred to the sediments by adsorption onto suspended matter and subsequent sedimentation (Ha ˚kanson and Jansson 1983). Sediments formed during the weathering processes could be modified markedly during transportation and subsequent deposition by chem- icals of anthropogenic origin (Chapman 1992). Therefore, sediments not only provide a record of catchment inputs, but also information on the watershed pollution and other anthropogenic influences with high local representativity. Studying the composition of surface sediments of the aquatic environment allowed us to understand the fate of the terrestrial materials transported into a basin and the factors responsible for controlling the distribution and geochemistry of sediments (Fo ¨rstner and Wittmann 1981). From among natural aquatic ecosystems, geochemistry of lake sediments has been used effectively and widely to evaluate the catchment weathering (e.g. Jin et al. 2006), environmental changes (Last and Smol 2001) and paleo- climatic reconstruction (e.g. Krishnamurthy et al. 1986; Das 2002). Lake sediments from the industrialized areas and densely urbanized regions, as well as from the rural unpolluted areas, have been extensively researched in the recent years, since they act both as a sink and a source of metals in the aquatic ecosystems. Previous studies have suggested that the anthropogenic inputs of metals could be R. Chandrajith (&) Á K. Mahatantila Á H. A. H. Jayasena Department of Geology, University of Peradeniya, Peradeniya, Sri Lanka e-mail: rohanac@hotmail.com R. Chandrajith Á H. J. Tobschall Institute of Geology and Mineralogy, University of Erlangen-Nu ¨rnberg, Schlossgarten 5, 91054 Erlangen, Germany 123 Paddy Water Environ DOI 10.1007/s10333-008-0133-y