Evaluating the ecological consequences of heavy metal contamination in soil induced by spent engine oil and palm oil mill effluents for sustainable development

Abstract

This study assessed the ecological consequences of heavy metal contamination in soil induced by spent engine oil (SEO) and palm oil mill effluents (POME) in Ebonyi State, Nigeria. Concentrations of zinc, nickel, mercury, manganese, lead, iron, copper, chromium, and cadmium were analyzed across contaminated and uncontaminated sites. The research, conducted at Ebonyi State University’s Presco Campus, employed rigorous sampling and analytical methods. Results revealed that soil contaminated with spent engine oil effluent exhibited elevated mean concentrations of zinc, nickel, manganese, lead, iron, copper, chromium, and cadmium compared to the palm oil mill effluent and control sites. Conversely, mercury concentrations were higher in soil contaminated with palm oil mill effluent. Comparative analyses highlighted unique dynamics, such as lead concentrations being highest at the control site, challenging general trends observed for other metals. Importantly, none of the mean concentrations exceeded the WHO acceptable limits at the time of the study, indicating compliance with internationally recognized safety thresholds. The findings underscore the need for tailored environmental management strategies, considering specific contaminants associated with each effluent type. Continuous monitoring is crucial to ensure sustained adherence to safety standards and prevent potential future exceedances. This study contributes a valuable understanding of the nuanced ecological impact of industrial effluents on soil quality in Nigeria, emphasizing the importance of sustainable practices for environmental protection.