INFLUENCE OF HEAVY METAL CONTAMINATION ON SOIL ENZYME ACTIVITIES

Hazardous heavy metal pollution of soils is one of the most important environmental problems throughout the world. In fact, heavy metals have a significant toxicity for humans, animals, plant and microorganisms. Our results indicate that enzymatic activities are a great utility for understanding the negative impacts of heavy metals in soils. Actual and potential dehydrogenase and catalase activities were determined in the 0-10, 10-20, 20-30 and 30-40 cm layers of a soil polluted with heavy metals. Comparing the soil enzyme activities in different seasons, it was found that seasonal differences were registered with higher soil enzymatic activities in the spring and in lower activities in the winter. The enzymatic indicators of soil quality calculated from values of enzymatic activities determined in the six places showed the order: NE/S > SE/E > NE/M > SE/M > NE/B > SE/B. This order means that by determination of dehydrogenase and catalase activities, which are considered as indicators of the global and respiratory activity of soil, valuable information can be obtained regarding fertility status of soils.