Environmental contamination caused by mercury is a serious problem worldwide. The study was conducted in order to identify Hg contamination in soil, technosoil from dumps, groundwater, and surface water in the surroundings of the abandoned Hg deposit of Malachov in Central Slovakia. Soil from the Malachovský brook valley was classified as cambi-soil (rendzina). The highest Hg concentrations (44.24 mg kg(-1)) were described in the soil from the mining area at the Vel'ká Studňa locality. In the groundwater, the maximal Hg content is 0.84 μg L(-1), and in the surface water it is 394 μg L(-1). The speciation study proved that in most samples, Hg occurs in the form of cinnabarite. The release of Hg into the environment as a consequence of weathering is limited.

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Acidity in surroundings of the abandoned Ľubietová-Podlipa Cu-deposit depends predominantly on the geochemical behaviour (weathering) of particular minerals (mainly pyrite). The article presents the results of measurements of basic physicochemical parameters - pH and Eh in technogenic sediments and in surface and drainage water of a dump-field. Although the dump material shows a significant amount of mobility-able metals and thus also a potential to form acidity, a massive AMD formation in future is not probable.

The more than 200 years old dump-fields at closed Cu (Ag) deposit Ľubietová are situated near the village settlement. Heavy metal space distribution is controlled by geochemical behaviour of the elements, depend on their content, solubility, migration and sorption ability. The major sources of metals to the country components (soil, technogenous sediments, groundwater, surface water, plants…) may be classified according to expected solubility of primary minerals. The content of heavy metals in sediments and soils at the studied dump-field shows irregular distribution. Also the heavy metal contamination of the surface water and groundwater was studied both in the rainy as well as during the dry periods. The speciation of As and Sb proved in the water presence both of As 3+ and Sb 3+ as well as the less toxic As 5+ and Sb 5+ species. In the soil and sediments prevail As 5+ and Sb 5+ species while in the water is often dominant the As 3+ and Sb 3+ form. The article also presents some results of the plant tissue degradation study under heavy metal contaminated conditions at dump-fields. The dump sediments and the primitive soil formed locally on the surface of the technogenous sediments show only limited acidification potential. The Fe 0-barrier installation at bottom of the down part of the valley seems to be a good solution for the groundwater decontamination.

The article presents the results of leaching experiments regarding the comparison of chemical and biological-chemical leaching of ores from the Sb-(Au-) base metal deposit Pezinok (Malé Karpaty., the Western Carpathians) under the same conditions in solution. Discussed are the differences between chemical and biological-chemical leaching activity. The extent and the kinetics of the biological-chemical leaching of the technogenous sediments from the setting-pits are significantly higher than those without bacteria.