Pollution Status Evaluation and Hydrogeochemical Facies Characterization of Surface and Groundwater Resources in Ishiagu Mining District, Southeastern Nigeria

Abstract

In this study, the impact of the continued uncontrolled mining of lead-zinc on the nature and quality of water sources in the Ishiagu Mining District of Southeastern Nigeria was evaluated. Fifteen water samples within the proposed influence zone at which the mine tailing can contaminate the water sources were targeted. These include samples collected from natural surface waters and groundwater as well as man-made reservoirs. The collected water samples were subjected to physicochemical analyses to ascertain the presence of possible contaminants. The results of the water sample analysis show that the mean values of pH, electrical conductivity and temperature are 4.09, 1.50µs/cm, 27.13 ⁰C, 0.09 µg/l respectively while the bacterial oxygen demand stood at 66.59 mg/l. Also, The chemical parameters-Na^+, Ca²⁺, Mg²⁺, K⁺ , Cl^-, HCO^3-, NO^3-, SO^4- and PO^4-had average concentration values of 186.82 mg/l, 100.56 mg/l, 16.52 mg/l, 5.09 mg/l, 687.95 mg/l, 194.54 mg/l, 1.85 mg/l, 0.90 mg/l and 0.11 mg/l respectively. Five water groups were discriminated based on characterization in the Piper trilinear diagram which include; Calcium-Chloride (Ca²⁺ + Mg²⁺ and Cl^- + SO₄²⁺), Magnesium-Bicarbonate (Ca²⁺ + Mg²⁺ and HCO₃^-), Sodium-Chloride (Na⁺ + K⁺ and Cl^- + SO₄^{2 -}), Calcium-Bicarbonate (Ca²⁺- HCO₃^-) and Calcium-Sulphate. These results indicate that the Ishiagu Mining District is hydrochemically acidic due to acid mine drainages resulting from mining activities in the area. The results also reveal that the mining zones serve as water source areas and zones of groundwater recharge. The surface water and groundwater resources in the study area have been directly impacted by mining activities in the area as evident in the results of sodium, sulphate, chloride, nitrate and carbonate which are above the WHO permissible limits for drinking water. This renders the water unsuitable for consumption as they pose serious health risks to human beings.

Keywords: Mining, groundwater, surface water, contamination, lead-zinc

DOI: 10.7176/JEES/11-2-10

Publication date: February 28^th 2021