Assessment of Heavy Metals Contamination of Surface Water and Sediment of a Tropical Manmade Lake Southwestern Nigeria (Published)
Developing countries including Nigeria are faced with increase generation of domestic, industrial, and agricultural wastes that enter into the surrounding water bodies; and pollutants settle on the sediment (the ultimate sink of contaminant in aquatic environment). These large amount of chemical substances (including heavy metals) released into aquatic environments has put it at risk which could inadvertently pose serious public health hazard. This study assessed the heavy metal concentrations of the surface water and sediments of Dandaru Reservoir, in Ibadan, Nigeria. The level of contamination of lake water and sediment were use to determine the degree of pollution and its potential effects on the environment and public health. Physical and chemical parameters and heavy metals were determined in the lake water using standard methods from April, 2015 to March, 2016 at five different sites of human activities. The physico-chemical parameters determined were within the limits specified by NESREA and WHO. All metals that were assessed were present in water and sediments (except nickel which was not determined in sediment). Metal concentration in the water followed the following trend Mn,>Fe>Pb>Ni>Zn>Cu>Co>Cd>Cr. Also, metal accumulation in sediments was Fe>Zn>Mn>Pb>Cu>Co>Cd>Cr. The average Igeo class for the sediments in all the stations was 0-2 indicating uncontaminated to moderately contaminated levels. The concentrations of Pb, Cd, Ni and Mn in water exceeded the NESREA AND WHO standards for domestic water use and aquatic life. These could have adverse effects on the environment and health of people that utilize the water and fish of the Dandaru Reservoir. Effective monitoring of the livelihood activities and discharges into the reservoir are recommended to prevent further deterioration of the reservoir.
Keywords: Contamination factor, Dandaru Reservoir, Geo-accumulation Index, Heavy Metals, Sediment
Using EF, PLI and Igeo for the Assessment of Heavy Metal Pollution and Sediment Quality of Asejire Reservoir, Southwest Nigeria (Published)
Asejire Reservoir is the largest lake in Southwest Nigeria, supplying domestic and industrial water to more than two million inhabitants of Ibadan and adjoining villages and towns in Oyo and Osun States. A study on the characteristic of sediment quality was conducted to evaluate the heavy metal content of the reservoir. Twenty stations were selected, sampled and analyzed using standard methods.Standard pollution indices such as Igeo, Enrichment Factor, Contamination Factor and Pollution Load Index were deployed to assess the level of heavy metals contamination in the reservoir. The result showed that the sediment was slightly acidic across the study stations, with low conductivity and organic matter content. The heavy metals order of dominance was: Fe>Pb>Cu>Zn>Mn>Ba>Ni>Cr. The mean concentration levels of all the heavy metals were lower than mean background value except Fe and Pb. Analysed data shows that the sediments in the area are rich in Fe with Igeo values > 6, high enrichment and contamination factor. Igeo and CF levels of Pb indicate moderate to no pollution, while other heavy metals indicated low calculated Igeo, EF and CF respectively. The calculated PLI values for all the heavy metals in all the location were < 1, indicating low anthropogenic contamination by these elements and suggesting that the heavy metals were derived mainly from natural sources such as bedrock materials and weathering processes.
Keywords: Asejire, Geo-accumulation Index, Heavy Metals, Pollution Load Index, Sediment