Assessment of Concentrations and Ecological Risk of Heavy Metals at Resident and Remediated Soils of Uncontrolled Mining Site at Dareta Village, Zamfara, Nigeria

Abstract

This study determined the levels of some heavy metals at resident and  remediated soils of uncontrolled gold mining activities with a view to  providing information on the extent of contamination and ecological risk to the resident area. The soil samples were collected from two site at the  resident and one remediated soil, and analyzed for metals (Cr, Ni, Pb, Fe, Cu, Cd and Mn) using Atomic Absorption spectrophotometer (AAS). The concentrations of heavy metals (mg/kg) in residents samples ranged from 1.500-13.30 (Cr), 0.0001-0.05 (Ni), 0.18-3.754 (Pb), 0.0003-0.10 (Fe), 0.0005-0.88 (Cu), 0.0009-0.27 (Cd) and 0.0003-0.0035 (Mn) and for the remediated sample are 12.3000, 0.0001, 1.1989, 0.0002, 0.0006, 0.0003, and 0.0003 for Cr, Ni, Pb, Fe, Cu, Cd and Mn respectively. The calculated geo-accumulation index (Igeo) shows that the soil samples fall under unpolluted to moderately pollute for all the studied metals with respect to all studied sites. Pollution Load Index values (PLI>1) were all less than 1 for each metals in all studied sites, thus indicating perfection. The  contamination factor (Cf) and degrees of contamination (Cd) of the soil samples were very slightly contaminated to slightly contaminated with Cr and Cd; The ecological risk results revealed that site A, B and Remediated samples were fall under low ecological risk index with values of 0.28,
10.28 and 0.33 respectively. The contaminations of these studied metals may not add ecological risk to the local environment.

Keywords: Assessment, Ecological risk Heavy Metals, Uncontrolled Mining