Ecological risk assessment of mercury and other heavy metals in soils of coal mining area: A case study from the eastern part of a Jharia coal field, India

Mercury (Hg) and other heavy metals, such as arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), lead (Pb), manganese (Mn), and zinc (Zn), were analyzed in coal (bituminous), roadside soil, reclaimed mine soil, core zone soil, and reference soil (agriculture soil) along three soil profiles (0-10, 10-20, and 20-30cm) in a coal mining area (Jharkhand, India) inhabited by economically marginalized dense population. Higher toxic metal concentrations in coal (0.47mgHg/kg, 2.81mgAs/kg, and 13mgPb/kg, 2.61mgCd/kg) can cause ecological hazard in the area. Roadside soil has the highest Hg (2.32mg/kg), and core zone soil has the highest Pb (15.7mg/kg) concentration. Hg concentration in roadside soil indicates high potential ecological risk, while Cd contamination in mining area can be put under moderate ecological risk. Roadside soils shows highest Ecological Risk Index (ERI) value of 339, indicating considerable ecological risk, and Hg alone contributes 64% of ERI value. Higher ERI and E-f(i) (Hg) were due to the deposition of coal dust from mining activities and transportation.