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- Armah, Frederick A., et al.
(författare)
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Anthropogenic sources and environmentally relevant concentrations of heavy metals in surface water of a mining district in Ghana: a multivariate statistical approach
- 2010
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Ingår i: Journal of Environmental Science and Health. Part A: Toxic/Hazardous Substances and Environmental Engineering. - : Informa UK Limited. - 1093-4529. ; 45:13, s. 1804-1813
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Tidskriftsartikel (refereegranskat)abstract
- The levels of heavy metals in surface water and their potential origin (natural and anthropogenic) were respectively determined and analysed for the Obuasi mining area in Ghana. Using Hawth's tool an extension in ArcGIS 9.2 software, a total of 48 water sample points in Obuasi and its environs were randomly selected for study. The magnitude of As, Cu, Mn, Fe, Pb, Hg, Zn and Cd in surface water from the sampling sites were measured by flame Atomic Absorption Spectrophotometry (AAS). Water quality parameters including conductivity, pH, total dissolved solids and turbidity were also evaluated. Principal component analysis and cluster analysis, coupled with correlation coefficient analysis, were used to identify possible sources of these heavy metals. Pearson correlation coefficients among total metal concentrations and selected water properties showed a number of strong associations. The results indicate that apart from tap water, surface water in Obuasi has elevated heavy metal concentrations, especially Hg, Pb, As, Cu and Cd, which are above the Ghana Environmental Protection Agency (GEPA) and World Health Organisation (WHO) permissible levels; clearly demonstrating anthropogenic impact. The mean heavy metal concentrations in surface water divided by the corresponding background values of surface water in Obuasi decrease in the order of Cd > Cu > As > Pb > Hg > Zn > Mn > Fe. The results also showed that Cu, Mn, Cd and Fe are largely responsible for the variations in the data, explaining 72% of total variance; while Pb, As and Hg explain only 18.7% of total variance. Three main sources of these heavy metals were identified. As originates from nature (oxidation of sulphide minerals particularly arsenopyrite-FeAsS). Pb derives from water carrying drainage from towns and mine machinery maintenance yards. Cd, Zn, Fe and Mn mainly emanate from industry sources. Hg mainly originates from artisanal small-scale mining. It cannot be said that the difference in concentration of heavy metals might be attributed to difference in proximity to mining-related activities because this is inconsistent with the cluster analysis. Based on cluster analysis SN32, SN42 and SN43 all belong to group one and are spatially similar. But the maximum Cu concentration was found in SN32 while the minimum Cu concentration was found in SN42 and SN43.
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| 2. |
- Armah, Frederick A., et al.
(författare)
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Impact of Floods on Livelihoods and Vulnerability of Natural Resource Dependent Communities in Northern Ghana
- 2010
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 2:2, s. 120-139
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Tidskriftsartikel (refereegranskat)abstract
- Sub-Sahara Africa is considered to be most vulnerable to climate variability including flooding. The frequency and severity of floods in Northern Ghana over the last decade has increased considerably. Through qualitative modelling the paper explores the impact of floods on natural resource dependent communities in Northern Ghana. Simplified causal loop diagrams are used to conceptualise flood-induced coping strategies in the study area. The results indicate that some characteristics of the socio-cultural environment appear to mitigate risk and reduce vulnerability. In this context, the role of social networks in enhancing livelihood security is essential. The paper concludes that both in case of seasonal variations in agricultural output and floods, individuals that have effectively diversified their livelihoods, both occupationally and geographically, are less sensitive than individuals who mainly achieve entitlement to food via crop cultivation. However, diversification in this case, is effective only in the short term.
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