An assessment on metal pollution in soils and native plants in Foromad mining area (East Meyamey, Semnan province)

The present study was initiated to assess the concentration and contamination level of arsenic, chromium, nickel, copper, zinc and lead in the soils and native plant species around the Foromad mining area (Eastern Meyamay, Semnan province). 15 surface soil samples and 5 dominant plant species were randomly collected from study area and their total concentration of metals along with the physicochemical parameters of the soil samples were measured using standard methods. The mean concentrations of arsenic, chromium, nickel, copper, zinc and lead in the soils are found as 9.90, 1182.5, 697.75, 32.10, 60.73 and 6.51 mg/kg, respectively. The maximum concentration of chromium, nickel and arsenic was measured in the mining area where the extracted mine wastes are piled. Based on the calculated geochemical indices (enrichment factor, geoaccumulation factor and pollution load index), the soils of Foromad mining area are heavily contaminated in terms of chromium and nickel. The results of multivariate statistical methods (correlation analysis and principal component analysis) indicated that chromium, nickel, arsenic and copper were derived mainly from anthropogenic sources. The calculation of source proportion of metals in the soils also confirmed that more than 70% of nickel and chromium, 67% of arsenic and 53% of the copper contents are roughly contributed from the anthropogenic sources. Comparing the average concentration of heavy metals in plant samples with their corresponding toxic ranges in plants also showed that chromium, arsenic and lead are within the safe and the normal range, respectively, while copper and zinc are within the toxic range and nickel metal is far beyond its toxic range. Based on the calculated biogeochemical indices (BCF and TF), Artemisia species among others can be considered as a potential candidate to remediate the nickel-contaminated soils.