Exploring the Impact of Cemetery Leachates on Groundwater Quality in Benin City Metropolis, South-South Nigeria

Abstract

Worldwide, research conducted under various time frames and environmental circumstances consistently identifies leakage from cemeteries as a significant contributor to groundwater contamination. The study evaluated the quality of groundwater from selected boreholes around second cemetery in Benin City metropolis, using electrical resistivity approach and water quality assessment method. Groundwater samples were collected randomly from fifteen (15) different boreholes around second cemetery. The water samples were analyzed in triplicates to obtain the mean value and standard deviation of each water quality test parameters. For the analysis of the water quality data, the average weighted index method was employed to estimate the overall water quality index (WQI) of individual boreholes. Factor analysis was use to analyse the information content of the water quality indicators in order to get reasonable information on the critical water quality parameters that requires adequate attention towards improving the overall groundwater quality around second cemetery. The spatial distribution of the WQIs was determined using Inverse Distance Weighting (IDW) while hydro-geochemical facies were inferred using an adaptation of the Piper-Hill diagram. The profile maps from both traverse obtained from the electrical resistivity data confirmed the cemetery operations as the source of the leachate plume resulting to the contamination of the subsoil. Evaluation of the WQIs indicated that more than 70% of the water samples collected around second cemetery was unsuitable for consumption and the degree of suitability of the borehole water was found to be positively correlated with distance from the cemetery. The outcome of the principal component analysis (PCA) revealed that; calcium, electrical conductivity, iron, dissolved oxygen, nitrite, chloride, pH, nitrate, sodium, zinc, sulphate, copper and carbonate are the parameters mostly affected by necroleachate from human decomposition. Hydrochemical analysis result shows that the origin and geochemical composition of the groundwater varied spatially. The types of water that have been identified include Ca-Cl₂, Mg-Cl₂, Ca-Mg-Cl₂, and Mg-Ca-SO₄.