The Onyi River in Nigeria is polluted by heavy metals from the cement industry, leading to high levels of toxic metals in its sediments. The researchers measured metal concentrations, organic matter, and sediment size to assess quality. Downstream sediments had higher levels of Co, Cd, Cr, Cu, Ni, Pb, and Zn, with Cd exceeding safety guidelines. Pollution indexes indicated sediment deterioration, and contamination levels were moderate. The river showed some capacity to purify itself, with varying effectiveness for different metals.