Various elements are accumulated in bottom deposits in concentrations that significantly exceed the levels observed in lake water. Under certain conditions, this can lead to secondary contamination of water, posing threat to aquatic organisms. The aim of this study was to evaluate the spatial distribution of Pb, Zn and Cr pollutants in the bottom deposits of Lake Sunia. The investigated water body is situated in the Olsztyn Lakeland western part of the Masurian Lakeland), approximately 30 km north of the city of Olsztyn, in the municipality of Swiatki. The lake has a total area of 111.6 ha and a maximum depth of 8.8 m. The inflow to and the outflow from lake are situated in its south-western and north-western part, respectively. The lake features a bay which is separated from the main water body by a shallow zone. Its catchment area comprises mainly agricultural land. The total area of supply of lake is 450 ha of which inflow catchment area is 70 ha. Most of the catchment area is agricultural land (91%), and in particular arable land, the rest of the area (5%) are the barren, and trees (4%). the area of the lake is dominated by power-sandy loam soil in the passing sands and clay loam strong little sandy. In terms of particle size are a summary of the soil that is difficult permeable to water and nutrients. Taking into account the valuation of soil classification in the vast quantities of soil are included in the class IVa, IIIa and IIIb. The average content of organic matter in the lake was determined at 24%. Significant accumulation of organic matter results from intense inflow of biogenic substances from farmed areas in the catchment. The average concentrations of trace elements in the analyzed water body were arranged in the following series: Cr < Pb < Zn, and their ratios were determined at 8.1 < 22.9 < 45.2. Higher levels of heavy metals were observed the profundal zone, whereas lower concentrations of the analyzed elements were noted in littoral zone sediments.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
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