Contaminant Levels and Ecotoxicological Effects in Sediments of the River Odra

Abstract

AbstractThe large‐scale analysis of contaminant levels in sediments in the Odra river basin during the study period from 1997 to 1999 showed that sediment quality varies according to the prevailing anthropogenic impacts. The levels of PAHs, Zn, and Cd in the Upper Silesian coal‐mining and metallurgy district are by a factor of four above the quality targets (Zielvorgaben) defined by the Working Group on Water of the German Federal States. In the Lower Silesian district that is dominated by non‐ferrous metallurgy, Cu and Hg were found in concentrations of a factor of three above the target values. Downstream of the inflow of the river Warta, the concentrations of Cd and of nutrients continue to increase, what suggests impacts of the electrotechnical/electronics industries around Poznan and emissions from agriculture.Temporal trends were recorded for heavy‐metal concentrations in sediments near Widuchowa. The maximum was observed in the year of the flood event 1997. Cd and As levels were nearly double the median throughout the study period. The flood wave transported contaminated sediments downriver. After the flood, the levels dropped below the values measured in the time before this event.In the German river reach, the flood had a diluting effect for organic contaminants, that continued with view to PCBs until 1999. The PAH load, however, rose again, because the anthropogenic activities on the upper river course continued.The ecotoxicological effect of sediments is tested by means of bacteria, algae, and daphnia in pore waters and elutriates. Algal toxicity was repeatedly observed in pore waters from all study areas, in those from the headwaters and Widuchowa also in combination with bacteria toxicity. Elutriates of sediments from the headwaters did not show inhibiting effects. PAHs are considered to play a major role in the toxicity of Odra sediments.