Accumulation, distribution and ecological risk assessment of heavy metals in sediments, case study: Shadgan wetland

Evaluating the metals concentration and their environmental risk for pollution monitoring is necessary to maintain the quality and the health of the ecosystem. In this study, the distribution and ecological risk assessment of heavy metals in the sediments of the estuaries around the petrochemical units were investigated. The purpose of this research is the pollution value and ecological risk assessment of heavy metals in the sediments in Shadgan wetland. A systematic method of random classification was used to determine the sampling points and 36 sediment samples were collected and transferred to the laboratory for analysis. Preparation and complete digestion of sediments were performed according to standard Mopam instructions. For analyze to of samples, was used ICP-OES model 730-ES device. Important environmental indicators such as the geochemical index (Igeo) and ecological risk index (ERi) were calculated. Based on the results obtained, mean concentrations of Ni, Pb, Hg, and V were 55.8, 8.5, 6.9 and 88.7µg/g, respectively. The research results showed that distribution pattern of heavy metals in the sediments was V>Ni>Pb>Hg. Based on Muller's geochemical index, pollution degree was severe contamination for nickel and lead, severe to very severe contamination for mercury, and moderate contamination for vanadium. The ecological risk index (ERi) analysis showed that the risk situation is considerable for Ni, Pb, and Hg and moderate for V. It can be concluded that the Shadgan wetland is contaminated with heavy metals due to the inflow of effluents from petrochemical industries. The use of modern treatment plants, decomposition of pollutants and the use of raw materials with a lower percentage of pollutants in wastewater management are necessary to reduce pollutants.