Mercury in Soil around a 2,600 MW Coal-Fired Super Thermal Power Plant in India and Human Health Risk Assessment

Abstract

Coal-fired power plants are major emitters of mercury, a toxic element of global concern, to the atmosphere. Although more than 100 coal-fired power plants exist in India, only a limited number of studies have assessed mercury levels in the soil surrounding these power plants. Here, we report the concentrations of mercury in the soil around a 2,600 MW coal-fired “super thermal power plant” in southern India and conduct a human health risk assessment for exposure to soil mercury. It was found that concentrations of mercury in soil were less than or similar to those observed in India or other parts of the world (2.4–40.2 µg/kg). Assessment of soil quality indexes, contamination factors (CFs), and geoaccumulation indexes (IGEO) suggests soil to be enriched in mercury compared with a local background (CF = 1–9, IGEO < 0 to >3). Concentrations of mercury in soil were inversely correlated with the distance from the power plant, but intermediate increases were also observed, owing to the interfering influences of an opencast coal mine, ash pond, or urban area. Human health risk assessment indicates that infants are at higher risk than adults, but the overall health hazard remained low (hazard index <0.05).