Water quality of Bomadi Creek in the Niger Delta of Nigeria: assessment of some physicochemical properties, metal concentrations, and water quality index

Abstract

AbstractIn this study, some physicochemical properties, concentrations of metals (Pb, Cd, Cu, Zn, Fe, and Mn), and the overall water quality from Bomadi Creek in the Niger Delta of Nigeria were assessed over two seasons. Water samples were collected from designated areas along the course of the river and were prepared for analysis by standard procedures. The ranges of the mean values for some water quality indicators were found to be as follows: pH: 7.40–8.17, turbidity (NTU): 20.5–42.3, total dissolved solids (mg L−1): 27.5–44.7, total suspended solids (mg L−1): 34.1–61.7, dissolved oxygen (mg L−1): 3.07–6.53, biochemical oxygen demand (mg L−1): 0.13–2.77, total hardness (mg L−1): 28.3–60.0, and nitrate (mg L−1): 0.37–0.92. Only the turbidity values exceeded the permissible limit of 5 NTU. The concentration ranges (mg L−1) for the six metal ions determined were: Pb: 0.01–0.02, Cd: 0.01–0.03, Zn: 0.1–0.3, Cu: 0.03–0.07, Fe: 0.6–0.9, and Mn: 0.01–0.05. There were no significant variations in many of the locations between the wet and dry seasons. The comprehensive pollution index values indicated severe pollution of the Creek, with Cd, Fe, and turbidity, identified as the major contributors to the deteriorated water quality. The sources of high loads of Cd, Fe, and turbidity in this river system include discharges from oil production activities, speed boats, illegal bunkering, and domestic waste dumps. Principal component and cluster analysis were used to establish relationships between the various parameters and sites. The risk assessment indicated adverse non-carcinogenic and carcinogenic risks arising from human consumption of the water. The risk is higher for children than adults. Therefore, the Bomadi water is considered unsuitable for drinking and other domestic purposes, and remediation is required.