عنوان مقاله [English]
Mighan playa in the central part of Arak watershed receives heavy elements from urban, industrial and agricultural activities. In order to evaluate the pollutants of Mighan playa, 29 sediment and soil samples were collected from playa and heavy metal concentrations were determined and compared with local and upper crust reference. The mean concentrations were found to be 4.03 mg/kg (for arsenic), 13 mg/kg (for lead), 50 mg/kg (for zinc), 53 mg/kg (for chromium), 33 mg/kg (for copper), 34 mg/kg (for nickel) and 0.21 mg/kg (for cadmium), respectively. The concentration of heavy metals in most samples is lower than their concentration in the crust reference. Individual contamination index, such as contamination factor, determined the degree of contamination in all samples medium for copper and chromium and low grade for other elements. But, indices such as ecological risk, enrichment index, and geological accumulation index were low for all samples. Also, integrated indices such as sum of degree of pollution, ecological risk potential and Nemerow index for sum of elements indicate low degree of contamination. Urban wastewater and industrial and agricultural wastewater are the most important source of heavy metals in the Mighan playa. Therefore, efforts should be taken to reduce heavy elements from pollutants, especially municipal sewage in the vicinity of the Mighan playa.