Geo-Accumulation Indices of Heavy Metals in Soil and Groundwater of Kanpur, India Under Long Term Irrigation of Tannery Effluent

Soil and groundwater from long-term (> 50 years) tannery effluent irrigated areas of Kanpur were analyzed and significant buildup of heavy metals such as Cr, Ni, Cd, Pb, Zn, and As in the range of 252-972, 23-30, 2.3-14.1, 23.7-58.8, 138-338 and 6.8-11 mg kg(-1), respectively in soil was found. Few groundwater samples in the effluent irrigated areas also exhibited high Cr concentration above the permissible limit of United States Environmental Protection Agency. The tannery effluents contained 1.53-57.3 ppm Cr, 0-0.12 ppm Ni, 0-0.02 ppm Cd, 0-0.07 ppm Pb, 0-0.48 ppm Zn and 0-0.03 ppm As. The Geo-accumulation index (I-geo) revealed that soil samples were unpolluted to moderately polluted with Cu, Ni, Zn, Pb and As; moderately polluted in case of Cd; and heavily to extremely polluted by Cr.