Occurrence of heavy metals in the waters of a heated reservoir (the Rybnik Reservoir, southern Poland)

The range of changes in the occurrence of heavy metals in the water was very wide, no seasonal trend being assessed in the changes of their content. The content of copper diminished with increasing depth of the sampling layer. In the water layer near the bottom an increase in the content of iron and manganese was observed. For the remaining metals no uniform direction of changes in their content depending on water depth was determined. An increased average level of zinc and copper was maintained in the Rybnik Reservoir in relation to the norms for purity class I, the mean content of the remaining metals not exceeding the norm. -Authors