Radionuclide and trace element contamination around Kolaghat Thermal Power Station, West Bengal - Environmental implications

The Kolaghat Thermal Power Station (KTPS), located at Mecheda in Midnapur District, West Bengal is one of the largest thermal power stations in eastern India. Combustion of coal in the KTPS generates large quantities of ash that are disposed-off in vast areas of land adjoining the power station. Geochemical and radiometric analysis of the pond ash has been undertaken to assess the quantity of toxic elements that are likely to contaminate the soil and the groundwater system. Trace element analysis reveals that toxic elements (Pb, Cu, Ni, Fe, As) are sufficiently enriched in pond ash than their crustal abundances, and preferably in the lighter size fractions. Radionuclides (U, Th) also show enrichment of 3-5 times in coal ash compared to their crustal average and are much higher than in the pond ashes of other thermal power plants in India. Chemical analysis of the water samples collected from tubewells near the ash ponds reveals high concentration of trace elements (Al, Li, Ni, Fe, As, Zn, B, Ag, Sb, Co, Si, Mo, Ba, Rb, Se, Pb V, Cr, Cu, Cd, Mn, Sr), whose distribution is mainly controlled by the ash deposited in the area. Among these elements, Al, Li, As, Zn, Ag, Sb, Si, Mo, Ba, Rb, Se and Ph show higher concentration in the tube-well waters near the ash pond, implying significant input from the ash pile. The enrichment of some elements (Al, Fe, As and Mn) above WHO guidelines for drinking water denotes significant contamination of the groundwater from the toxic elements leached from the ash pile.