Stepánka Stánová1 (email@example.com), Martin Mihaljevic2 (firstname.lastname@example.org), Ondrej Sebek3 (email@example.com) & Jirí Kuhn2 (firstname.lastname@example.org)
1 U.F.R. des Sciences de la Vie, de la Terre et de l' Environnement, 3 place Victor Hugo, 13331 Marseille, Cedex 03, France.
2 Institute of Geochemistry, Faculty of Science, Charles University, Albertov 6, 128 43 Praha 2, Czech Republic.
3 Laboratories of the Geological Institutes, Faculty of Science, Charles University,
Albertov 6, 128 43 Praha 2, Czech Republic.
Elevated levels of metals often occur in the wastes from galvanizing industries (Fergusson, 1991). Vinor river basin (Prague district - Czech Republic) is well-known for its anthropogenic metal pollution. High concentrations of toxic metals in bottom sediments were observed,especially Cr (15,000 mg kg-1), Zn (8,000 mg kg-1), Cd (2090 mg kg-1; SebekCadmium and other heavy metals originate from PAL Kbely (machine factory), where these metals were used for steel protecting. Because of high toxic effects of Cd, geochemical investigation of polluted sites and study of heavy elements in plants have been initiated.
Element partitioning among the geochemical phases in sediments was studied to indicate the risk of toxicity and the nature of the geochemical controls over heavy metal mobility. The original contaminated sediments were strongly anoxic. Following the dam reconstruction, originally anoxic sediments were aerated, dried and frozen. Partitioning of heavy elements in sediments was studied with respect to previous history e.g. drying and freezing of sediment samples. Data from leaching experiments have shown that oxidation drastically changes the binding form especially for Cd and Zn in the sediments. After drying, the stable fraction of Cd and Zn in the sediment decreased, which could have resulted in mobilisation of the heavy metals into surface and subsurface water reservoirs.
High concentrations of heavy elements were found also in plants growing on dried basin sediments (Stánová, 1995). The increase of heavy element concentrations in plant tissues and high accumulation factor ([Me]plant / [Me]soil) were observed especially for osiers (Salix sp.) and poplars (Populus sp.). Accumulation factor varies with the plant type and each element with the exception of Cu.
For copper, chromium, cadmium and zinc it was found that [Me] roots> [Me] shoots. [Me] roots< [Me]shoots was observed for Pb, Hg, Ni, Co and Mn. In contrast to heavy metal accumulation patterns, the ratio for iron ([Fe]roots /[Fe]shoots) depends on the plant type only. While most of the element contents in the plant tissue increase during vegetation season, contents of Cu decrease during vegetation time.
Fergusson, J.E. The Heavy Elements: Chemistry, Environmental Impact and Health Effects. (Pergamon Press , Oxford, 1991).
Sebek, O. Speciation of metals in streams sediments of the Vinor river (in Czech). MSc. thesis, Faculty of Science, Charles University, Prague (1993).
Stánová, S. Heavy elements in the plants in the Vinor river watershed (in Czech). MSc. thesis, Faculty of Science, Charles University, Prague (1995).
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