Trace metal contamination of the Dyje River stretch between Znojmo and Nové Mlýny, Czech Republic

Abstract

The analyses of seven trace metals (Hg, Zn, Ni, Cr, Cu, Pb, Cd) in the water, bottom sediments, macroinvertebrates and fish tissues were conducted at two localities on the Dyje River, Czech Republic, at different distances downstream from the Znojmo Reservoir (at 12 and 31 km) to evaluate a contamination level. The maximum admissible limits were exceeded in Hg in the water and in the case of Ni in bottom sediments at both localities and also in Hg in zoobenthos sample at locality further from the reservoir. In regard to trace metal contamination of fish tissues, it was found that safe limits for mercury, cadmium and lead were not exceeded. Mercury and cadmium contents have declined markedly since the 1990s, but the amount of lead has increased. Human consumption of fish caught in the Dyje River is most limited by concentration of Hg in the fish muscle. The maximum tolerated intake was set as high as 3.80 kg per week.

Keywords

• water quality
• sediments
• mercury
• cadmium
• lead
• chub (<i>Squalius cephalus</i>)