Assessment of Heavy Metals Contamination and Enzymatic Activity in Pine Forest Soils under Different Levels of Anthropogenic Stress

The aim of this work was to assess heavy metal concentrations and the effects of these metals on soil enzymatic activity in polluted and potentially unpolluted forest areas. The study was performed in typical pine forests located in three heavily polluted (in the immediate vicinity of a zinc smelter, an iron smelter, and a power plant) and three relatively clean sites (a nature reserve, an ecological site, and an unprotected natural forest community) in southern Poland. The research concerned the activity of acid phosphatase, dehydrogenase, beta-glucosidase, and urease. In the soils, taken from the top 0-10 cm layer, we also tested the concentrations of heavy metals (Cd, Fe, Pb, and Zn) extracted with 10% HNO3 and 0.01 M CaCl2, and their pH and organic matter contents. Single pollution index and Nemerow pollution index were also calculated. Nemerow pollution index indicated serious pollution with heavy metals at two sites. The lowest activity of soil enzymes (acid phosphatase, and in particular beta-glucosidase) was found in the site with the highest levels of heavy metals. In this study we found no effect of organic matter on the activity of the selected enzymes. There was a significant effect of pH on the activity of acid phosphatase and beta-glucosidase.