Evaluating sediment metal pollution and risk indices efficiency in interpreting stream sediment pollution around abandoned barite mine sites, Southeastern Nigeria. – C. I. Adamu
This study assessed the efficiency of sediment metal pollution and risk indices in interpreting sediment metal contamination associated with barite mining activities in parts of Oban Massif and Mamfe Embayment, Southeastern Nigeria. Results of the stream sediment analysis showed enhanced levels of As, Ba, Cu, Fe, Pb, and Zn relative to background values as contained in control samples and average shale values (ASV). In spite of the high concentrations of Ba and Fe, they have very low extraction rates (ER< 10%) in sediment samples and are not major threat to the aquatic system. Evaluation of enrichment factor (EF), background enrichment index (BEI), pollution load index (PLI) and degree of contamination (CD) revealed varying degrees of sediment metal contamination ranging from low (Mn, Ni) to extreme (Ba, Pb). The ecological risk factor (Er) indicated that Al, Fe and Mn fell within the low risk category; Ni and Zn fell within low to moderate risk; Cr fell within low to considerable risk category; Ba and Cu fell within low to high risk while As and Pb fell within considerable to very high risk and high to very high risk categories respectively. The mean risk index (RI) ranked the mine sites in decreasing order of potential risk of sediment metal pollution as Nde> Alese> Iyametet> Okumuretet> Akpet 1=Ibogo. The significant positive correlation of extraction rates with Er (0.84) and RI (0.85) indicates that risk index is the most efficient method in interpreting sediment metal pollution in the study area.