ABSTRACT

Rivers are the important sources of water all around the world. River water can be contaminated with heavy metal loads from weathered soils and rocks, mining and metallurgical releases and industrial release. Heavy metals pollution in aquatic ecosystems has become a global concern due to their potential toxic effect and ability to bioaccumulate in aquatic ecosystems. Ossah River was studied from January to June 2018 in three stations and compared with national and international standards to evaluate its heavy metal contents as well as assess its potential human health risk. The water samples were collected from below the water surface using a 1 liter sampler and were transferred to a prewashed plastic bottle where they were acidified with Nitric acid. Eight (8) heavy metals (Iron, Manganese, Zinc, Copper, Chromium, Cadmium, Nickel and Lead) were evaluated using Atomic Absorption Spectroscopy (AAS). The range of metal concentrations recorded were as follows: iron (1.11 2.98 mg/1), Manganese (0.09 0.38 mg/1), Zinc (0.55 1.33 mg/l)5 Copper (0.03 0.30 mg/1), chromium, (0.02 0.11 mg/1), Cadmium (0.02 - 0.08 mg/1), nickel (0.01 0.04 mg/1), lead (0.02 - 0.14 mg/I). Some values ofthe metals recorded such as (Fe, Mn, Zn5 Cr and Cd) exceeded national and international standards and warranted Health Risk Assessment. One way analysis of variance (ANOVA) test showed that there were significant differences in the metals in the stations. Correlation analysis showed positive and significant relationship among the metals while pH showed negative significance with some metals. The human health risk assessment showed that Hazard Quotient of Fe, Mn, Zn, Cr, Cd and Ni were all greater than unity and poses a health risk to both adults and children exposed to the river water through ingestion. The heavy metal contamination observed in this study was of anthropogenic source including sand mining and vegetable oil effluent discharge and can be regulated.