Occurrence of Microplastics, Pesticide Residues, and Heavy Metals in Surface Water of Kura Local Government Area, Nigeria

This study presents a comprehensive review of the occurrence and interactions of microplastics, pesticide residues, and heavy metals in surface waters, with particular focus on identifying knowledge gaps that necessitate investigation in Kura Local Government Area, Nigeria. The review synthesizes findings from global studies demonstrating that microplastics are ubiquitous in aquatic environments, with abundances ranging from 0.2 to 3.8 items per liter, and that these particles function as effective vectors for both heavy metals and pesticides through sorption mechanisms enhanced by plastic aging and biofilm formation. Agricultural watersheds are identified as multi-contaminant hotspots due to the convergence of plastic debris from farming activities, pesticide applications, and metal inputs from fertilizers and amendments, yet integrated assessments examining all three contaminant classes simultaneously remain exceptionally rare. The literature reveals a severe underrepresentation of West African contexts, with no studies comprehensively characterizing microplastic-pesticide-heavy metal co-occurrence in Nigerian surface waters despite intensive irrigation agriculture in regions like Kura along the Watari River. Critical knowledge gaps include the absence of baseline data on multi-contaminant pollution in Nigerian freshwater systems, lack of field validation for contaminant interaction mechanisms under tropical African conditions, and insufficient understanding of seasonal and spatial distribution patterns in agriculturally dominated watersheds. This review establishes the scientific rationale for integrated field investigations in Kura Local Government Area to quantify contaminant occurrence, assess potential interactions, and support evidencebased water quality management for communities dependent on these critical freshwater resources for drinking, sanitation, fishing, and irrigation.