Geochemical Distribution of Heavy Metals in Soil around Itakpe Iron-ore Mining Area-a Statistical Approach

摘要

This study becomes imperative in order to determine the degree of soil contamination due to iron-ore mining. Ten surface soil samples were collected and analyzed for major ions and heavy metals during the dry season. Average cation concentration observed was: Ca＞K＞Na＞Mg while the heavy metal average were: Fe＞Ni＞Cd＞Zn＞Cu＞Pb. The regression analysis result indicates generally weak associations among the variables though moderate relationships were observed between Ni-K, Pb-Mg, Pb-Fe and Zn-Cu. Five indices were used for data evaluation: Anthropogenic Factor (AF), Index of Geo-accumulation (Igeo), Enrichment Factor (EF), Contamination Factor (CF) and Pollution Load Index (PLI). Except EF which gave the order of enrichment: Fe＞Ni＞Pb＞Cu＞Zn＞Cd, AF, Igeo and CF reveals this order of contamination: Fe＞Pb＞Ni＞Cu＞Zn＞Cd. PLI shows that the locations experienced various degrees of deterioration in this order: ITK14＞ITK10＞ITK04＞ITK02＞ ITK01＞ITK07＞ITK06＞ITK05 (ITK17) ＞ITK03. R-mode factor analysis suggests that factor one is due to natural and anthropogenic influence while factors two and four are due to natural processes. Factor three points to anthropogenic origin. Q mode factor reveals anthropogenic factor as the dominant influence. R-mode cluster indicates that cluster four is anthropogenic and three natural while clusters two and three are a mixture of natural and anthropogenic sources. Q-mode cluster analysis shows that clusters one, two and three are directly influenced by iron ore mining while four were not. The soils around Itakpe iron ore have experienced various degrees of contamination particularly with reference to Fe, Pb and Ni and locations ITK14, ITK10, ITK04, ITK02 and ITK01. This area needs to be reclaimed and soils treated appropriately while norther and a detailed study on the ecosystem is recommended.