The Use of Pollution Indexes to Discriminate between Natural and Anthropogenic Heavy Metals in Soils

anglais. The aim of current study is the use of pollution indices to assess the influence of (1) the bedrocks, as a natural source of heavy metal in soil developed above them, and (2) anthropogenic pollutions (ore mining and processing) of the soil. The research was conducted in two areas, varying in terms of geological setting and type of land use, in the Upper Silesia Industrial Region, Southern Poland. The total Zn, Pb and Cd contents (ICP-OES) for 39 topsoil samples were measured. All metal contents exceeded, from 2.5– to 42.4–fold, geochemical background levels. The selected pollution indices such as CF, CD, PLI and Igeo were calculated to indicate deterioration of topsoil quality due to metal pollution. Depending on the index used, we determined very high to moderate topsoil contamination. The influence intensity of particular metals differs between studied areas. It follows the order Pb > Cd > Zn for shallow historical mining area and the sequence Zn > Cd > Pb for area of deep mining and processing. Based on Igeo values, we consider that the heavy metal content in the topsoil developed over the shallowly occurring ore bodies in dolomites is mainly (60%) connected with natural presence of metals, while in the area where ore bodies are more deeply buried, the 90% of metal load is related to anthropogenic sources. Finally, we come to a conclusion that the realistic assessment of soil quality, according to heavy metal content, is possible only with the combined use of various pollution indices.

anglais. Pollution indexes, Heavy metals, Soil contamination, Geogenic and Anthropogenic origin

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