ASSESSMENT OF HEAVY METALS IN WATER, SEDIMENTS AND TISSUES OF CITHARINUS CITHARUS FROM LOWER RIVER NIGER AT AGURO, AJAOKUTA, KOGI STATE

This study assessed the concentration and bioaccumulation of heavy metals in water, sediment, and fish tissues from the Lower River Niger at Aguro, Ajaokuta, Kogi State, Nigeria. The specific objectives were to determine heavy metal concentrations in water and sediment, evaluate bioaccumulation in Citharinus citharus, and assess potential human health risks from consuming contaminated fish. Primary data were collected through water, sediment, and fish samples from three sites along the river in May, June, and July. The samples were analyzed using Atomic Absorption Spectrophotometry (AAS) for metals like iron (Fe), lead (Pb), nickel (Ni), chromium (Cr), cadmium (Cd), and zinc (Zn). The findings show that Fe concentrations in water peaked at 11.679 mg/kg in July, exceeding the WHO guideline of 0.300 mg/kg, while Pb and Ni concentrations surpassed WHO limits at all sites across the three months. Sediment analysis revealed that Fe ranged from 168.282 mg/kg to 244.800 mg/kg, with Cd peaking at 0.841 mg/kg in July. In fish tissues, Fe concentrations were highest in gills (51.121 mg/kg), followed by viscera (48.403 mg/kg), and muscle (34.921 mg/kg). The Estimated Daily Intake (EDI) for zinc in gills reached 2.99 × 10⁻² mg/kg/day, while the Target Hazard Quotient (THQ) for Cr in gills was 0.127, signaling a moderate health risk. The study concludes that heavy metal contamination in the Lower River Niger poses significant ecological and human health risks, particularly during the rainy season. It recommends stricter regulation of industrial discharge, regular sediment dredging, public health campaigns on fish consumption, and continuous environmental monitoring to mitigate the long-term impacts of heavy metal pollution.