Degradation of forest soils in the vicinity of an industrial zone

Abstract

Forest soils near industrial zones can be endangered by acid deposition and by dust deposition containing potentially toxic elements (PTEs). Soils of the study area are acidified and the surface enrichment with Cd, Cu, Pb, and Zn reflects anthropogenic contamination. Two forms of all PTEs were evaluated: potentially mobilized (2M nitric acid extraction) and mobile (0.01M CaCl2 extraction) - the most toxic form. Negligible amounts of Cu and Pb were found in the mobile form. Pb mobilization is decreased by co-emitted bases and Cu mobilization is mainly controlled by soil reaction. These elements represent just a potential risk for the ecosystem. The mobile forms of Cd, Zn, and Mn account for approximately 30% of potentially mobilized forms in organic horizons. These elements could pose a problem to ecosystem vitality. Cd is toxic at small concentration and its content in mobilized form approaches the critical load. Cd can be considered the most dangerous element in the study area. Zn concentration is not reaching the limit value. Mobilization of Zn and Pb is mainly controlled by Ca and Mg content. The highest concentrations of Mn were found in the mineral horizons. It predicates a geogenic origin. The lowest percentage of the mobile form is in mineral horizon and its mobilization is controlled mainly by pH. Based on these results, a direct damage of forest by PTE contamination in the Silesian Beskids can be excluded. Lower contamination level along with acid condition and P deficiency could act as a permanent stress factor. Stressed forest is more predisposed e.g. to frost or insect damage.

Keywords

• acidification
• contamination
• toxic elements