Mobility and toxicity of heavy metals in bottom sediments of Rybnik reservoir

Heavy metals are one of the most important factors among many others in biosphere pollution. Mobility and toxicity of metals associated with bottom sediments are generally affected by metal speciation and sediments compositions. The aims of this study were to investigated the distribution of metal speciation in sediment collected from Rybnik dam reservoir and to asses their toxicity for aquatic ecosystem. The speciation analysis of metal was performed using the three-step method of sequential fractionation by means of the modified BCR technique. Toxicity assestement of the bottom sediment samples was preformed using tests: PhytotoxkitTM, Ostarcodotoxkit FTM, Microtox r. According to the above results, the mobilization potential of heavy metals in sediments in a decreasing order (fraction I+ II): Zn > Cd > Ni > Pb > Cu > Cr. According to the Risk Assessment Code (RAC), the sediments having at low risk (Pb, Cu, Cr), medium risk (Cd, Ni) and high risk (Zn). The analysis of all sediment samples collected from the suited reservoir showed that Classes III (acute hazard 50% = PE < 100%) was represented by 80% samples.