Speciation of Arsenic and Determination of Heavy Metal Levels in Drinking Water at Amansie West District
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Date
2013-03-19
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Abstract
A study of arsenic speciation and heavy metals (Zn, Pb, Cd, Hg and Fe) content in drinking water of Amansie West District was conducted. Drinking water samples from boreholes, hand dug wells and streams were taken from 23 communities in the district. Amansie West is a gold mining community with surface mining being the main method used. Anthropogenic activities such as mining, agricultural and urbanization have led to the contamination by arsenic in streams and rivers. As (III) and As (V) in the water samples were separated using hydride generation and detected by flame AAS. Determination of Hg was also made by HG-AAS. Analysis of the other heavy metals were done using flame AAS.
The results obtained showed that the concentration of arsenic in streams, boreholes and hand dug wells fell between 0.24-37.22 μg/L, 13.49-26.41 μg/L, and 24.11-39.43 μg/L respectively. Test of correlation between arsenic concentration and some physical parameters (pH, DO, conductivity and redox potential was done to ascertain any relationship. For speciation study, results showed that arsenic (III) is the dominant inorganic arsenic species. On average, 64% of all inorganic arsenic species was in the more toxic (+3) oxidation state, the rest is in the (+5) oxidation state. There was a strong negative correlation between arsenic speciation and the redox potential.
91 % concentration of Zn, Pb, Cd, and Hg measured was below detection limits. The 9 % that was measured were below WHO acceptable limit for drinking water. However, the concentrations of Fe (0.141 – 1.082 μg/L) in the water samples were high
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A thesis submitted to the School of Graduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirement for the award of Master of Science degree, 2013