[Heavy metal content in sediment samples taken from drinking-water reservoir (author's transl)].

Sediment samples were taken from the small preliminary catchment basin of the Wahnbachtal reservoir at Siegburg, extracted under mild conditions with nitric acid and hydrogen peroxide and analysed for their content of heavy metals. The sediment sample of the most recent date showed the highest concentrations of metal, that of older date revealed lower values, but by far the lowest metal content was found in the clay of the former valley. The high metal contents in the sediment are not only to be attributed to human influence but are primarily caused by the lead and zinc ores in the catchment area. The hygienic significance of these results is to be seen in the remobilization processes which could lead to an undesirable increase of metal concentrations in the raw water fed to the drinking water treatment plant.