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 increasedsoils tracemetals concentration in many parts of the world. in this article wereport the results of a study onimpacts of agricultural activities on soilaccumulation of cadmium, cobalt, chromium, copper, nickel and lead and risk of metal contamination in hamedan provinceusing contamination factor. the soil samples were collectedsystematicallyfrom agriculture fields with cultivation period of 65, 35 and 20 years. the results showedthe mean concentration of cd, co, cr, cu, ni and pb in the soils was increased withthe cultivation periodand a significant difference was seen between the concentrations of metals, except for pb, in the soil under different cultivation periods. the trendof soils tracemetal accumulation ofcd, co, cr and cu was exponential, whereas for ni and pb, it was quadraticand linear, respectively. also, based on the calculated contamination factors, the soils classifiedas none and none to medium class pollution were generally found in lands with more length of cultivation.the increase of tracemetals concentration in the soil followed the increase in the use of fertilizers in the region. the cultivated soils thus provide awayfor 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.