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A part of Raniganj coalfield, eastern India, covering an area of about 156 km2 (60 mi2), was studied to identify the impact of mining on geoenvironment, in terms of heavy-metal mobilization. Twenty-eight soil samples were taken from four major landuse classes, viz., mining area, land with or without scrub, agricultural field, and social forestry area, and analyzed for pH, electrical conductivity, organic carbon, and heavy metals (Fe, Mn, Zn, Cu, Ni, Co, Cr, Pb, Cd, and As). Intermediate groundwater flow system of the area was inferred through the fitting of polynomial trend surfaces to the water-table elevation data from 55 observation wells for premonsoon, monsoon, and postmonsoon periods. Quantitative analyses of 17 groundwater samples (7 from mining areas and 10 from nonmining areas) were carried out with special reference to heavy metals (Fe, Mn, Zn, Cu, Ni, Co, Cr, Pb, Cd, and As) during these three periods. Twigs of selected planted species used in reclamation of one of the mine spoils in the area were also analyzed for heavy metals (Fe, Mn, Zn, Cu, Ni, Co, Cr, Pb, Cd, and As). Impacts of mining have been measured in terms of erosion and heavy-metal mobilization from mine spoils to the surrounding geoenvironment. Leaching on mine spoils followed by surface runoff contaminated the soil with heavy metals, whereas leaching followed by percolation contaminated the groundwater with heavy metals. Effects were inferred in terms of changing ecosystem. Native plant species like Shorea robusta, Terminalia tomentosa, etc. are being replaced by smaller species like Butea monosperma, which appears to be more tolerant in this changed ecosystem.
Sahadeb De is a research assistant professor at the University of South Carolina, Columbia. He received his B.S., and M.S. degree, and his Ph.D. in geology from the University of Calcutta and his M.S. degree in environmental resource management and his M.E. degree in computer engineering from the University of South Carolina. His areas of expertise include environmental information and decision support systems, natural resources, environmental impact assessment, and management plan.Arup K. Mitra is a professor of geology at the University of Calcutta and acted as head of the department during 1999–2001. He received his Ph.D. from the University of Calcutta, and his present research interests are in the fields of environmental geology and hydrogeology using remote sensing and geographic information system.