Physicochemical and trace metals characterisation: An impact assessment of Badagry Creek on groundwater quality in Ojo Community, Lagos, Nigeria

Abstract

Groundwater is a major source of water supply with comparative advantages including convenient availability of water close to where it is required, and near excellent natural quality. However, groundwater quality is often compromised by various threats, both of natural and anthropogenic origins, including intrusion from big water bodies like seas. The aim of this study is to assess the possible impacts of Badagry creek on groundwater quality in Ojo community, Lagos. Fifteen (15) groundwater samples were collected from different hand-dug wells during both dry and wet seasons for physicochemical and some trace metal analyses using standard procedures. The physicochemical parameters analyzed included pH, electrical conductivity (EC), total dissolved solids (TDS), anions (NO₃^-, PO₄^3-, Cl^-), and some trace metals (Fe, Zn, Ca, Mg, Cu, Na, Pb, and K). Principal Component Analysis (PCA), Correlation Coefficient, and Cluster Analysis were applied on the data obtained. The concentrations of EC, TDS, and NO₃^-, were observed to be higher above World Health Organization (WHO) permissible limits, with values of 0.94, 0.81, and 2.92% respectively. Very strong correlation coefficient was observed between EC and TDS, Cl^-, and NO₃^-. Four principal components were extracted, and hierarchical dendrogram showed four (4) distinct clusters of wells. Iron and lead had mean concentrations above the WHO allowable limits which portends health risk. The quality of the groundwater investigated was questionable, especially with respect to high concentrations of NO₃^-, pointing at influence from the Badagry creek. Hence, there is need for regular monitoring, to ensure safety of man and sustainable environments.