Factors influencing the accumulation of Pb in sediments of deep and shallow dam reservoirs

The study determines the differences in Pb accumulation in sediments of dam reservoirs with respect to locations of the old river beds and their depth (deep Czorsztyn Reservoir and shallow Goczałkowice Reservoir in southern Poland). Parameters (grain size, organic matter content and reservoir depth) that may influence the spatial distribution of Pb concentrations in the sediments were analyzed. Based on the hierarchical cluster analysis, sediment samples from the reservoirs were ranked with respect to particle size distribution. We found differences in the spatial distribution of grain size and organic matter in the studied reservoirs, caused mostly by the topography of these reservoirs. The spatial distribution of Pb concentrations in the sediments of the Czorsztyn Reservoir (range 4.8-35.8 μg g^-1) and the Goczałkowice Reservoir (range 11.3-59.4 μg g^-1), regardless of their average depth and their type (dimictic, polymictic), depends on the distribution of silty clay and clay fractions, organic matter and reservoir depth. Therefore, Pb spatial distribution was more regular in the Czorsztyn Reservoir than in the Goczałkowice Reservoir. Locations of the old river beds had a significant impact on the Pb distribution in the sediments of both reservoirs.