The distribution of heavy metals in sediments in the lake Talska of Lithuania

Abstract

The intensification and development of industrial processes has harmful effects of human activities on nature and entire environment. Having performed the assessment of contamination of environmental components, especially geological environment (soil, sediments from bottoms of water bodies, including sapropel), it is possible to make a quantitative evaluation of the scope of anthropogenic influence and often the hazardousness of such influence on biota and people. Heavy metals enter water reservoirs and, at the same time, sapropel from atmosphere and with surface-water and underwater. Part of heavy metals, which are found in deeper deposits of sapropel, have built up naturally in the course of complex hydro-chemical and hydro-biological processes, which formed over thousands of years when the atmosphere and waters were not as polluted as they are today. A large number of sediment samples representing most of the active accumulation areas in Lake Talksa of Lithuania were studied for total copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), lead (Pb) and manganese (Mn). Quantities of most heavy metals in sapropel decline noticeably with depth, if compared to the surface layer. The lowest concentrations of heavy metals arc discovered at a depth of 200-250 cm. The trend of declining concentration of heavy metals in sapropel layers with depth is obvious throughout the section.