Assessment of Pb, Zn, As, Ni, Cu, Cr and Cd in Agricultural Soils around Settlements of Abandoned Lead-Zinc Mine in Mkpuma Ekwoku, South-eastern, Nigeria

Abstract

This study was carried out to assess the level, distribution and the contamination status of Pb, Zn, As, Ni, Cu, Cr and Cd in agricultural soils around the settlements of Abandoned Lead-Zinc Mine in Nkpuma Ekwoku, Southeastern, Nigeria. The mean concentrations of the heavy metals, Pb, Zn, As, Ni, Cu, Cr and Cd are 109.55, 210, 1.83, 2.34, 8.24, 12.66 and 8.57 mg/kg respectively. The values obtained were compared with the established soil sediment standard by Canadian Council of Ministers of Environment (CCME). Generally most samples around the abandoned Pb/Zn mine show higher concentration of Pb, Zn, Cd, and Cr compare to individual Effect Range Low (ERL) values of the elements while Cu, and Ni were below both Effect Range Low (ERL) and Effect Range Medium values. However, Cd and Cr exceed the Effect Range Medium of the elements. Pollution Load Index (PLI) was found to be generally low in all the locations whereas the contamination factor (CF) values for metals like Pb, Zn and Cd are >1 while CF values of As, Cu, Cr and Ni are <1. The contamination is most probably resulted from the mineralized veins and mining of the ores.

Keywords: heavy metals; soil contamination; lead-zinc; Mkpuma-Ekwoku