Assessment of Physicochemical Constituents of Abattoir Effluents from Jimeta-Yola Abattoir and Their Impacts on Dissolved Oxygen Levels in River Benue, Adamawa State, Nigeria

Abstract

Abattoir effluents can alter the physicochemical condition of receiving waters and affect dissolved oxygen (DO). This manuscript presents an assessment of physicochemical constituents of abattoir effluents from Jimeta-Yola Abattoir and their impacts on dissolved oxygen levels in River Benue, Adamawa State, Nigeria. A descriptive field and laboratory assessment was conducted at three locations—upstream, the effluent discharge point and downstream—in River Benue around Jimeta-Yola Abattoir from February to July 2026. Three individual samples were collected monthly at each location, homogenised into one composite sample, and each composite was analysed in triplicate. Temperature, pH, electrical conductivity, turbidity, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), total dissolved solids (TDS), nitrate, phosphate, iron (Fe), zinc (Zn) and lead (Pb) were determined using standard procedures. Six-month mean DO concentrations were 3.72 mg/L upstream, 3.61 mg/L at the discharge point and 9.71 mg/L downstream. Wet-season DO was lower than dry-season DO at all locations, while wet-season BOD and COD were generally higher. Phosphate, Fe and Pb exceeded the adopted benchmark values at all locations. Several parameters were higher upstream than at the discharge point, indicating that the observed loading was not attributable solely to the abattoir discharge. Overall, the results indicate parameter-specific and spatially variable water-quality conditions, with localised oxygen stress at the discharge point and substantial downstream oxygen recovery. Continued monitoring and improved effluent management are warranted.