The river and lake sediments contamination in Slovakia is closely related to industrial and agricultural activities. Two kinds of industry had extraordinary role in the past. One of them is related to metal processing and production starting with ore mining and ending with metal casting and rolling, the next one is chemical industry.
One of the most significant sediment contamination cased by chemical industry is the PCB pollution of the írava lake sediment which is discussed in details in other contribution of this workshop.
During the last millennium the ore mining and processing was probably the most important industry in the current Slovak territory. Most of the ore mines are located in the Slovenské Rudohorie Mountains (the Slovak Ore Mountains). Although most of the mines were closed in the 90s, the stream sediments still remain heavily polluted by heavy metals, especially by Hg, Cu, As, Sb and Ba, as it is very well documented by the Geochemical Atlas of Slovakia (Bodis and Rapant, 1999). In my contribution I will discuss more in details the upper part of the Hornád river basin, where the main heavy metal pollution sources are the Rudnany and Slovinky ore mines and the sludge deposits related to the ore processing units nearby the abovementioned ore mines. The less important but still significant contamination sources are the Kovohuty copper foundry and the related industrial waste deposit in the city of Krompachy. These industrial sites are polluting the Hornád river sediments down to city of Kosice, including the Ruzin River dam sediments.