Assessing the heavy metal contamination in sediments of Mighan playa using pollution indices

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 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 Cu and Cr and low grade for other elements. However, indices such as ecological risk, enrichment factor, and geo-accumulation index were low for all samples. Moreover, integrated indices such as sum of degree of pollution, ecological risk potential and Nemerow index for sum of elements indicate low degree of contamination. Municipal wastewater, 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.