Anthropogenic sources and environmentally relevant concentrations of heavy metals in surface water of a mining district in Ghana: a multivariate statistical approach

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.

Gold Mining in Igun Ijesha, Southwest Nigeria: Impacts and Implications for Water Quality

“…The guideline value for cadmium is given as 0.003 mg/L in Science Publications AJES drinking water by both the World Health Organization (WHO, 2004) and the Nigerian standard for drinking water quality (SON, 2007). Previous studies show maximum levels in groundwater to be 0.003 mg/L (Kortatsi, 2004;Armah et al, 2010) and 0.06 mg/L (Oluwasanya and Martins, 2006). Maximum levels in surface water were less than 0.05 mg/L (Kuma and Younger, 2004;Yem et al, 2013).…”

Assessing the Impact of an Operating Tailings Storage Facility on Catchment Surface and Groundwater Quality in the Ellembele District of the Western Region of Ghana

“…Chronic and acute poisoning by arsenic due to exposure to elevated concentrations is a common occurrence. High arsenic concentration in TSF-DW could be attributed to leaching of the element by cyanide from arsenopyrite ore mined by ARL (Armah et al, 2010). Welch, Lico, & Hughes (1988) reported that arsenic is an important auxiliary contaminant in mine waters, particularly where the ore bodies contain arsenopyrite as is the case at ARL.…”

“…Contents of TSFs could therefore be highly contaminated and are therefore not discharged directly into the environment in conformity with international best practice for mining industries. It is therefore imperative to properly manage tailings as they constitute a major source of release of many trace elements and other contaminants into the environment (Armah et al, 2010).…”

Prospective Health Risk of Exposure to Fine Particulate Matter and Its Elemental Composition in Shoe Industries in Agra

“…Mn and Pb are also associated with Zn (r=0.99 and 0.82) indoors, which may due to the emissions of paints, varnishes usage, in leather industry, along with polluted road dust [33]. The high correlations between heavy metals in air may reflect the fact that these heavy metals had similar pollution levels and similar pollution sources such as shaving, buffing and anthropogenic activities [34,35].…”