Assessing the groundwater quality of a small-scale mining drainage basin using modified water quality indices

Abstract

This present study was aimed at investigating the effects of mining activities on groundwater quality of Enyigba-Ameri, Nigeria. Assessment of the impacts of mining activities on trace metal pollution in water was carried out using modified trace metal pollution index (m-TPI) and modified ecological risk index (m-RI). Water samples were collected during the pre-mining (PRM) and post-mining (POM) and analyzed for their physicochemical and trace element concentrations. The computed m-TPI for the PRM has a mean positive index (PI) value of 0.950 and a negative index (NI) mean value of −0.081. The m-TPI for POM has a mean PI value of 126.002 and NI mean value of −0.001. The m-RI for Pb+Zn ranged from 7.769 to 175.090 at the POM, and the m-RI for Cd+Zn for the PRM ranged from 8.772 to 47.349. The m-PI results revealed that all the water samples during the PRM were good for drinking and domestic uses but were all of “unacceptable quality” during the POM. Also, the results showed that 12.5%, 50%, 25%, and 12.5% of the water samples were of very high, high, moderate, and low Cd+Zn ecological risk respectively during the PRM. But during the POM, 50%, 12.5%, 12.5%, and 25% of the samples belong to very high, high, moderate, and low Pb+Zn ecological risk respectively. The decrease in the quality of water from the PRM to the PRM suggests anthropogenic pollution of mining activities. Therefore, legislation against indiscriminate waste discharges is recommended to reduce the adverse effects on the water resources.