Assessment bioavailability of selected heavy metal concentration and biological control parameter changes in two soils (case study: polluted and non-polluted sites in Iran)

Heavy metal pollution of soil is a serious concern, because such metals have toxicological importance in ecosystems, animal and human health. Metal toxicity depends on the chemical forms in which they exist. The aim of this research is investigation of biological factors and chemical forms of zinc and cadmium in two soils. We used two types of soil (polluted and non-polluted) in pot experiments that were conducted under greenhouse condition (similar to actual condition) as randomized complete factorial design. In according to this aim, the effect of this different on the soil biological factors, chemical properties, cadmium and zinc speciation was investigated in 21 and 49 days after treatment ancubation. Speciation was assayed with four individual extraction methods (distilled water, Ca(NO3)20.2M, DTPA+TEA 0.005M and HNO3 4N) in the bulk soil. The results showed that elements extractable concentration is following that Zn and Cd (HNO3)> Zn and Cd (DTPA+TEA)> Zn and Cd (Ca (NO3)2)> Zn and Cd (distilled water) in two soils. By approximately 91% and 61% of zinc and cadmium concentration is extractable with HNO3, respectively. These results showed one of the factors that caused to dangerous decrease may be related to be in unavailable and residual forms.In this study, zinc is more percent than cadmium in unavailable forms (i.e extractable with HNO3).Non- polluted soil is more microbial activity than polluted soil. Polluted soil was less microbial respiration rate (44%) and dehydrogenase activity (50%) than non-polluted soil