Physiochemical Properties and Levels of Selected Heavy Metals in Some Rivers around Ewekoro Local Government, Ogun State, Nigeria

Abstract

This study examines the physiochemical properties and concentrations of selected heavy metals in selected river waters around Ewekoro, an area characterized by intensive mining and industrial activities, particularly cement production. The research aims to assess the impact of these activities on water quality by analyzing parameters such as pH, electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS), total hardness (TH), and alkalinity, alongside heavy metal concentrations (copper, zinc, iron, lead, cadmium, calcium, arsenic, and nickel). Twelve (12) water samples were collected from three rivers—Akinbo, Alaguntan, and Elebu using atomic absorption spectrophotometry. Results indicate that most physiochemical parameters fall within WHO, NAFDAC, and FOEN permissible limits. Elevated levels of iron (0.18–1.449 mg/L) and lead (up to 0.52 mg/L) were detected, exceeding recommended thresholds. The Heavy Metal Pollution Index (HMPI) revealed localized contamination, with values ranging from 1.14 to 6.69, indicating varying degrees of pollution, particularly in areas influenced by industrial discharges. Low dissolved oxygen levels (2.7–3.66 mg/L) suggest organic pollution, posing risks to aquatic ecosystems. Despite the general compliance with international water quality standards, the elevated concentration of Fe, Pb, TH, and alkalinity highlights potential environmental and public health risks, hence there is a need for continuous monitoring, stringent enforcement of industrial discharge regulations, and targeted remediation strategies to mitigate pollution and protect public health. These findings highlight the critical role of industrial activities in water quality degradation and emphasize the importance of sustainable water resource management in the region.