Heavy metal pollution in soils and plants in conditions of Slovakia

Accumulation of potendtially toxic chemical compounds and elements, particularly heavy metals in the soils, has great influence on the quality of the soils and environment. The sources of soil-heavy metal pollution in Slovakia are mainly due to geochemical occurrences (mostly mountainous regions) and metallurgical activities. The effect of pesticide and fertiliser application is comparatively lower. Strongly polluted areas occupy only 0.4% of total soils in Slovakia. Common heavy metals in the terrestrial environment are Pb, Hg, Cd, Cr, Cu, Ni and Zn, and some of them such as. Cr, Cu, Ni, Zn are essential for plant growth while Pb, Cd and Hg are non-essential for plant growth and among the most toxic heavy metals. The reactions and the toxicity effects of the potentially toxic elements depend on pH, CEC, quantity and quality of humus, texture, redox conditions and interactions between the solid and liquid phases. The results concerning soil and plant pollution depend significantly on the extraction methods. The plant uptake of heavy metals partly correlates with the total content of heavy metals in soil. The highest correlation coefficient was determined between the soil available heavy metal content and plant contends where 0.05M EDTA was used as the extraction solution. High plant uptake of heavy metals resulted in the decrease of biomass quantity and quality of plants. The increased amount of toxic heavy metals in food plants resulted in the yield decrease by about 50%. Pollutants were accumulated in plant biomass only on strongly polluted soils.