Assessment of Leachate Pollution Index and Greenhouse Gas Emission at MSW Dumpsites along Ganga River at Varanasi, India

Abstract

Recent scientific attention has shown serious concern towards municipal solid wastes (MSW) as a source of greenhouse gases and concentrated leachate. We studied the leachate pollution index (LPI) and emission fluxes of two greenhouse gases (CH4 and CO2) at two municipal solid waste dumpsites situated along the Ganga River at Varanasi (India). The LPI is a quantitative tool by which the leachate pollution data of dumping sites can be reported uniformly. Concentration of nutrient ions (Ca2+, Mg2+, Na+, K+, NO3-, Cl-, PO43- ) and heavy metals (Cd2+, Fe2+, Cu2+, Pb2+, Ni2+, Zn2+, Co2+, Mn2+ ) in leachate varied with season with values being highest in rainy season. Total dissolved solids, conductivity and salinity in leachate showed a similar trend. Leachate pollution index was found to be 87.19 and 82.56 at KZP and BPS sites respectively. The LPI was much higher than the permissible limit at both the sites indicating high contamination potential for surface and ground water and risk to human health. Among all the study metals, Pb was found in abundance at Site 1. The emission flux of CH4 ranged from 10.73 to 96.74 mg m-2 h-1 and that of CO2 from 17.28 to 321.89 mg m-2 h-1. Emission flux of both the greenhouse gases increased with rising moisture and temperature. The rates were higher at young landfill site and between-site differences in the emission of CH4 and CO2 were significant. The study has relevance establishing landfill associated contamination to Ganga River and reducing uncertainties in greenhouse gas emission estimates in India.