Assessment of Physicochemical Contaminants in Waters and Fishes from Selected Rivers in Nasarawa State, Nigeria

Abstract

Levels of physicochemical parameters (pH, phosphate, chloride, nitrate, bicarbonate, turbidity, conductivity, alkalinity, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, temperature, total hardness and total solid) and microbiological properties were determined in the water samples collected from Rivers Doma, Farinruwa and Mada in Nasarawa State, Nigeria using standard analytical techniques. Metals (Na, K, Ni, Cu, Mg, Fe, Ca, Zn, Pb, Cd, As, Se, Cr and Mn) were also determined from two different fish species (Tilapia zilli and Clarias lazera) caught from these three rivers using atomic absorption spectrophotometer (AAS). The results of physicochemical analyses showed that phosphate and nitrate ions were not present in the water samples during dry season but present in the wet season. Other physicochemical parameter values fall within WHO standard limits. Microbiological tests revealed that Rivers Doma and Mada were not safe for drinking. Magnesium had the highest concentrations in the bodies of two fish species irrespective of the season when the fish was caught followed by calcium while the least concentrated metal was arsenic. Lead and cadmium in the fish samples were not within the detectable range of AAS. Nickel level in the fish sample from Mada River during dry season exceeded the WHO maximum tolerable limit. Therefore, source protection is proposed for these bodies of water for the benefit of mankind because they were not safe for human consumption.