Horizontal and vertical variability of heavy metals in the soil of a polluted area.

摘要

The Pribram region belongs to the most polluted areas in the Czech Republic. Atmospheric deposition of potentially toxic elements from lead smelter represents the main source of contamination in this region. The most polluted location intensively used for agriculture situated northeast from the source of contamination was investigated. The individual sampling points were positioned by GPS (Global Positioning System) and representative samples were taken from 0-60 cm split into three 20 cm layers. In the soil samples total Pb and Cd contents, plant available contents of these toxic elements and soil pH were determined. The total Cd content at the investigated site reached up to 13 mg/kg and Pb up to 2500 mg/kg in the top layer. The concentration of both elements decreases with depth and in the 40-60 cm layer the maximum content of only 6 mg Cd/kg and 400 mg Pb/kg was found. The plant available content of Pb and Cd in the soil is related to the pH value. The correlation coefficient of exponential regression for Cd is -0.799 and for Pb is -0.787. The obtained data was processed by Surfer 7 software resulting in digital maps of horizontal and vertical contamination of this location. This observation confirmed the airborne source of soil contamination. However, some of the individual sampling points suggested local geogenic contamination of the soil where more detailed further research is required.