Evaluation of sediment pollution by heavy elements using geochemical data and pollution indicators (case study: Eraghi basin in Esfaryen city)

Due to various activities, heavy metals can be released in the environment and endanger the health of people in the society. Considering the importance of the subject, the present research has investigated the contamination of Araghi catchment basin sediments with heavy elements. For this purpose, 24 sediment samples were collected and the concentration of 11 heavy elements, including arsenic(As), cadmium(Cd), cobalt(Co), chromium(Cr), copper (Cu), iron (Fe), Molibden(Mo), nickel (Ni), lead(Pb), vanadium (V)and aluminium(Al), were studied and pollution indicators were used to measure pollution. Based on the calculation of the enrichment index and according to the classification of Chen (2007), Mo (with an average of 0.91), Cu (with an average of 0.92) and Fe (with an average of 0.96) are among the elements without enrichment (less than 1) and the elements of Pb, Cr, As, Ni, Co and V are in the slightly enriched range in the region. Based on this index and the Anthropogenic Percent, the origin of all the studied elements is in the lithogenic area, which is caused by the weathering and erosion of the rock units of the area. The results of examining the Contamination factor, Modify Contamination Degree, Pollution Load Index and Geoaccumulation Index showed that the sediment samples in the study basin did not show any specific pollution and were classified as non-polluted. The average Ecological Risk index and Modified ecological risk index were obtained as 50.38 and 114.07, respectively, which according to Hakanson's classification, the state of Ecological Risk index and Modified ecological risk index of sediments in the studied area are low for heavy elements.