Assessment of heavy metals concentrations in tropical agroecosystem (Wakwa, Adamawa, Cameroon): An Index Analysis Approach

Abstract

A study has been conducted to evaluate the degree of Heavy Metals (HM) contamination on farm soils of Wakwa’s, using enrichment factor (EF), geo-accumulation index (Igeo), pollution load index (PLI), Ecological risk factors (Eⁱ_r), ecological risk indices (PER) and statistical analysis. In this study,  composite  surface agricultural soil samples were collected in 4 sites and analyzed for the concentration of HMs including As, Ba, Co, Cr, Cu, Ni, Mn, Mo, Pb, Sr, V, Y, Zn and Zr. The concentrations of Cr, Zr, Mo and Pb are significantly higher than average shale values in all sites. Sites WK₃ and WK₄ were also contaminated with Ni and V. The EF vary from 0.07 for Sr to 2.35 for Mo and indicate zero to moderate enrichment. Igeo vary from -3.83 for Sr to 1.26 for Mo and indicate zero to moderate contamination. A PLI vary from 0.61 to 0.83 with the highest to the lowest polluted site being WK₄ >WK₃ >WK₂ >WK₁.  All HM present low ecological concern and low potential ecological risk indices. Site WK₄ which is upstream the Lake Piu is the most polluted. Positive and highly significant correlations were observed for several pairs; this could indicate the same source of pollution for most HM. This study concludes that a regular assessment is needed to estimate the risk level of toxic metal contamination in the ecosystem. This study is valuable because it is probably the first work on heavy metal levels in Wakwa locality.