Risk Assessment and Ranking of Heavy Metals in the Sediments of Sarcheshmeh Copper Mine Using FDAHP and ELECTRE Methods

Heavy metals are considered the serious pollution source for the environment because of their stability, atomic and biological accessibility problems. The sediments of Sarcheshmeh copper mine in Iran contain high concentrations of these pollutants. Thus, environmental evaluation and ranking them based on emission levels are important for timely environmental measures with the lowest operating costs. The first aim of this study is to evaluate the environmental risk of these sediments by determining the contamination factor, pollution load index, enrichment factor and Geoaccumulation index. The second aim is ranking these metals based on the level of risk critical using the Multi-Attribute Decision Making (MADM) method. Method: In this study, first, by determining risk evaluation indices, heavy metals contamination (Co , Cu , Mo , Zn , Cr , Mn , Ni , Pb , Ti and Fe ) in the sediments of Sarcheshmeh copper mine which conduce to the tailings dam was assessed. Then, by collecting expert opinions on the relative importance of each indicator mentioned in the environmental contamination risk of heavy metals, through final weighting of the indices using Fuzzy Delphi Analytic Hierarchy Process (FDAHP), ranking and clustering of heavy metals in the sediments of the study area were performed using ELECTR method. Results: Based on the results measuring the risk evalution indices, the intensity of contamination related to these metals was in order of Zn> Cu> Fe> Mo> Pb > Mn > Cr, and all the metals except for copper, zinc and iron were almost cited to be in the unpollutant limit. Also based on ranking results, the ten risks were clustered in seven categories with copper, iron and zinc having the highest pollution and critical risk amongst the heavy metals in the studied sediments, respectively. Conclusion: Considering the boilers with high energy consumption and low efficiency in this factory, the replacement of old boiler with the new one through CDM project is cost effective.