Mahnaz Mohammadi; Kamal Siahcheshm; Saeed Mohammad Sorouraddin
Abstract
Introduction: Oxidation of sulfide-mineralized zones during weathering, intensifies by the biological and chemical reactions and the released acidic mine drainage (AMD) mobilizes toxic and heavy elements from the parent rock and concentrates them in soil or water environment. The village of Doustbaglu ...
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Introduction: Oxidation of sulfide-mineralized zones during weathering, intensifies by the biological and chemical reactions and the released acidic mine drainage (AMD) mobilizes toxic and heavy elements from the parent rock and concentrates them in soil or water environment. The village of Doustbaglu is located in a mountainous area to the northwest of Meshgin-shahr city, has numerous farmlands overlooking the extensive alteration zones. Field studies indicate the fact that unfortunately, especially skin diseases, liver and cancer are prevalent in the area. The importance of knowledge of heavy metal enrichment in soil resources and the high potential of Doustbaglu area for the production of agricultural and horticultural crops and its direct relationship with human health reveals the necessity of conducting this study to evaluate heavy metal contamination and identify possible sources. Material and methods: In this study, total concentration and bioavailability of heavy metals including: As, Cd, Cu, Cr, Pb, Sb, Ni and Zn in 70 surface soil samples were evaluated by ICP-MS analysis. Calculation of contamination rates of soil samples using different environmental indices including modified contamination index, soil heavy metals ecological risk index, pollution load index and Nemerow’s index indicates high contamination occurrence of these elements. Results and discussion: The results of mCd index show high degree of contamination of Cu, Cr, Cd, Pb, Sb, Ni, Zn and As in most samples. High values of the ecological risk index (up to 2076/9), indicate the level of serious contamination risk of some samples. The PLI index in 10 samples showed PLI valuesConclusion: Based on the results of geo-environmental indices, all eight studied elements showed highecological risk potential and significant contamination occurrence in stream sediments and surface horizons ofthe Doustbaglu district.
