Impact of agricultural activities on accumulation of Cadmium, Cobalt, Chromium, Copper, Nickel and Lead in soil of Hamedan province

Use of chemical fertilizers, pesticides and sewage sludge in agriculture lands have increased soils trace metals concentration in many parts of the world. In This article we report the results of a study on impacts of agricultural activities on soil accumulation of Cadmium, Cobalt, Chromium, Copper, Nickel and Lead and risk of metal contamination in Hamedan Province using contamination factor. The soil samples were collected systematically from agriculture fields with cultivation period of 65, 35 and 20 years. The results showed the mean concentration of Cd, Co, Cr, Cu, Ni and Pb in the soils was increased with the cultivation period and a significant difference was seen between the concentrations of metals, except for Pb, in the soil under different cultivation periods. The trend of soils trace metal accumulation of Cd, Co, Cr and Cu was exponential, whereas for Ni and Pb, it was quadratic and linear, respectively. Also, based on the calculated contamination factors, the soils classified as none and none to medium class pollution were generally found in lands with more length of cultivation. The increase of trace metals concentration in the soil followed the increase in the use of fertilizers in the region. The cultivated soils thus provide a way for entrance of trace elements in the human’s food chain. Therefore, monitoring contaminated soils is necessary to control and prevent the risks from contaminated soils.