Assessment of Physico-chemical Parameters and Heavy Metal Concentrations in Well Water of Logo 2 Area of Makurdi, Nigeria

Abstract

In this study, the concentration of six heavy metals (HMs) in well water: Cadmium (Cd), Copper (Cu), Lead (Pb), Manganese (Mn), Nickel (Ni), and Zinc (Zn) were determined from ten hands dug wells in Logo 2 area of Makurdi, Nigeria for samples labelled A to J using the flame Atomic Absorption Spectrophotometer (AAS) model PG 990. Sample dissolution was carried out using the open acid digestion method. The results obtained showed that HM concentrations in the wells in this area were in the following ranges Cd 0.0072 – 0.0149 mg/L; Mn 0.0413 – 0.6117 mg/L; Ni 0.0013 – 0.0157 mg/L and Zn 0.0758 – 0.4975 mg/L; while Cu and Pb were undetectable for all wells. The concentrations of HMs in the wells studied were arranged in descending order as Mn>Zn>Cd>Ni. Cd showed 100% contamination above World Health Organization (WHO) and National Industrial Standards (NIS) Maximum Permissible Guidelines (MPGs) for all the wells assessed, Ni and Zn had all their values 100% below the Maximum Permissible Guidelines set by WHO and NIS while Mn concentrations of 4 samples of the wells (40%) fell above the MPGs and 6 samples of the wells (60%) fell below the MPGs for Mn set by WHO and NIS. The physicochemical parameters: pH, temperature, Dissolved Oxygen (DO), Total Suspended Solids (TSS), and turbidity assessed in this study all fell below the permissible levels for drinking water guidelines of WHO and NIS. The study shows that well water in this area is safe for drinking with respect to the physicochemical parameters, Ni and Zn but not safe for Mn and Cd while Cu and Pb were not detected. The authors strongly recommend proper health education and sensitization against the domestic usage of water from hand-dug wells in this densely populated area to prevent residents of the area from health risks associated with heavy metal contamination of well water presently patronized by the majority of them since HMs are non-biodegradable and bio-accumulate. Also, laws governing Environmental Impact Assessments and wastes management in cities and towns should be strengthened, and strictly implemented to curb the web of the utilization of waters from such wells.