Evaluation And Characterization Of Trace Metals Contamination In The Surface Sediment Using Pollution Load Index (PLI) And Geo-Accumulation Index (Igeo) Of Ona River, Western Nigeria

Abstract

Evaluation and Characterization of Trace Metal Contamination in the Surface Sediment Using Pollution Load Index (PLI) and Geo-accumulation Index (Igeo) Index of Ona River was conducted for six months. From the result of this study, the mean values of lead ranged between 0.004 mg/kg and 0.330 mg/kg, while the mean iron was highest (5.05 mg/kg) in station 4 and lowest (2.26 mg/kg) in station 5. The mean chromium value ranged from 0.007 mg/kg (station 1 and 2) to 0.021 mg/kg (station 3 and 4). The mean copper was highest (3.97 mg/kg) in station 1 and lowest (0.008 mg/kg) in station 2. Analysis of variance (ANOVA) revealed the same trend in spatial variation of these heavy metals. There was a significant difference (P 0.05) in iron among the study sampling station. The PLI values recorded for all the stations were below 1. Thus the sediment of the study stretch that Ona River is unpolluted. The Igeo values for chromium and iron fall in class '0' in all the five sampling stations, indicating that there is no pollution from these metals in the Ona River sediments, lead fall in class '3' in station 4indicating moderately to heavily contaminated condition and class '0'in station 1, 2, 3 and 5 and copper fall in class '3' in station 4 and 5, in class '6' in station 3 indicating extremely contaminated condition. The Igeo values were consistent with those derived for PLI. All trace metals had concentrations below the EPA regulatory limits for sediment except iron. From the results of this study, sediment quality reflects the impacts of anthropogenic activities on quality of the river. However, the continuous build-up of the metal contaminants can be checked if relevant government agencies ensure strict compliant of industrial standards which stipulate treatment of industrial waste before discharging such contaminated effluents/wastes into River. Therefore, perpetual assessment is highly recommended to minimize the potential health hazards of the people who surely depend on the River water for fishing and agricultural purposes.