Assessment of heavy metals contamination and pollution around mining sites of Anka, north-west Nigeria

Abstract

Artisanal mining is a common practice in Anka communities, North-West Nigeria, and this has brought about serious environmental and health concerns in the area. This study assessed the concentration of heavy metals in the rocks, soils, sediments and plants in the mining environment of Anka. Thirty two samples were collected and analysed for K, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb using Energy Dispersive X-ray Fluorescence. The results obtained showed the heavy metal concentration in rock > soil > sediment > plant. The evaluation of the contamination factor in soil and sediment revealed that all the samples were severely contaminated. The results of geo-accumulation index revealed that the contamination with heavy metals was generally higher in rock and soil; followed by sediment while plant samples accounted for the least contamination. The result of the contamination factor and pollution index of soil and sediment indicated severe contamination and pollution respectively. The contamination assessment was complemented with the use of contamination degree and the modified contamination degree indices. The assessment of contamination factor and potential ecological risk from heavy metal in both soil and sediment was shown to come majorly from Pb, Ni and Cu. Active mining sites found in Dareta, Daki Takwas, Dan Kamfani and the processing areas of Abare, Dan Kamfani, Dateta and Abare were identified as areas with high heavy metal pollution risk. These results generally show that artisanal mining and processing in the study area pose significant environmental risk to the local population and the environment.