ASSESSMENT OF SELECTED HEAVY METAL CONTAMINATION, MODIFIED DEGREE OF CONTAMINATION AROUND LEAD ZINC MINE IN THE ENYIGBA, SOUTHEASTERN NIGERIA.

Abstract

This paper focuses on heavy metal (Pb, Zn, Cu, Cd and As) contamination, modified degree of contamination in the soils of Enyigba, southeastern Nigeria. Pollution by these metals was examined using several calculation methods: modified degree of contamination and geoaccumulation index. The proposed modified calculation method of degree of contamination, which involves the determination of the arithmetic mean of contamination factors by individual studied metals, revealed moderate contamination to very high contamination by metals. And the modified degree of contamination was moderate to ultra-high. These results were further supported by values obtained from indices of geoaccummulation method of pollution assessment. The spatial distributions of the three main controlling processes- rock weathering/water-rock interaction, mining activities factor and salinity factor across the study area were revealed. This evaluation would serve to create a consistent calculation method as a contribution towards building a consensus on methodologies applicable to the study of polluted soils.