Environmental Impacts of Pb/Zn Mining in Enyigba, Abakaliki, Nigeria

Environmental geochemical studies at Enyigba Pb-Zn mining district near Abakaliki, SE Nigeria were undertaken to characterize the distribution of Heavy Metals in rocks, mine dumps and soils, and the impact of mining activities on water sources. The geochemical studies included sampling, partial leach tests and chemical analysis for As, Cd, Ca, Co, Cu, Mn, Ni, Pb and Zn using UV-Spectrophotometer (for rocks, dumps and soils) and Atomic Absorption Spectrophotometer (AAS) (for water). Contents of these metals in Average Shale, Crust and Normal Soil were used as control. Results revealed high concentrations of some of the metals in the sampled media with decreasing concentrations with distance from known Pb/Zn mining sites for mostly Cd, Pb, As and Ni. Their potential environmental risks evaluated using enrichment and contamination factors, indices of geoaccumulation, contamination and metal enrichment showed generally high values for Cd, As and Pb. Compared with permissible limits and standards generally, the concentration is in order Cd> Pb> Cu> As> Co> Zn> Ni (for rocks), Cd> As> Pb> Zn> Co> Cu> Ni (for dumps) and Cd>> Cu>Co> Pb> As> Ni> Zn (for soil).