The Elbe river: A special example for a European river contaminated heavily with mercury

Elbe river, running through the Czech Republic and Germany is polluted heavily by a large variety of chemicals, but mercury is the dominant pollutant. Chloralkaline plants in the Czech Republic and in Eastern Germany, as well as an acetaldehyde production, discharged often more than 25 t Hg/year into the river and its tributaries, The measured concentrations for total mercury often exceed 100 mg Hg/kg in sediments or suspended matter, compared to a background of about 0.2 mg/kg. The organic species of mercury encountered are methylmercury compounds in both the sediments and the floodplain soils and dimethylmercury in the soil air. These concentrations vary during the year: the highest concentrations are found in summer, as shown by the analysis of sediment cores. The speciation of mercury changes along the length profile of the Elbe river: as the mercury is transported towards the North Sea, its association with high molecular weight humic substances increases.