Distribution of Nickel, Copper and Cobalt in the Grain Fractions of Bottom Sediments of the Sokołda River and its Tributaries (Poland)

In recent years, the interest in the occurrence of heavy metals in the natural environment has been observed. The heavy metal contamination can lead to serious environmental problems. The aim of the study was to estimate the total content of heavy metals: Ni, Cu and Co, in the surface layer of the bottom sediments of the Sokołda river and its tributaries, and to determine the relationship between the grain size and scope of their metal content. Determination of metals in the bottom sediment samples was performed by means of atomic absorption spectrometry (ASA). The research on the Sokołda river and its tributaries showed low levels of Ni, Cu and Co. It was proven that the majority of studied metals were contained in the smallest clay fraction <0.02 mm. On the other hand, the least studied metals were accumulated in 1.0–0.2 mm and 0.2–0.1 mm fractions. The 1.0–0.2 mm and 0.2–0.1 mm fractions contain around 80% of the tested metal forms, while the 0.02–0.063 mm and <0.02 mm fractions – only a few percent. This speaks for the determination of metals in the 1.0–0.1 mm fraction, that contains both coarser and clay fractions, and thus most reliably reflects the actual load of pollutants carried by the sediment. Studies have shown that the main sources of pollution in the Sokołda river catchment are primarily surface runoff, and to a lesser extent, wastewater (municipal and industrial).