Conceptual Model for Arsenic Distribution and Its Relationship with Groundwater Depth

International Journal of Research and Scientific Innovation (IJRSI) | Volume VII, Issue X, October 2020 | ISSN 2321–2705

Conceptual Model for Arsenic Distribution and Its Relationship with Groundwater Depth

Alexander Kwaku Banson¹, Richard Kwasi Amankwah², and Samuel Agyarko Ndur^3
1Perseus Mining Ghana Limited, Ghana,
^2,3 University of Mines and Technology, Ghana

Abstract: In this study, arsenic distribution in groundwater and its relationship with the depth of groundwater was studied. During the study, water samples were taken from wells and community boreholes in the Obuasi Municipality. The samples were analyzed, and models were developed to provide a better understanding of arsenic distribution and groundwater depth. The study concludes that, at greater depth in community boreholes (CBH > 50 m), there is a positive correlation of depth with total arsenic indicating total arsenic mobilization whereas in shallower depth (wells and CBH < 50 m) the correlation is not very clear suggesting total arsenic may be mobilized or demobilized depending on prevailing conditions. There is contribution of microbial activity in the mobilization of arsenic in the groundwater. Arsenite mobilizes with increasing borehole depth and demobilizes with decreasing borehole depth. In wells, there appear to be two arsenite groups all negatively correlated with depth. There is positive correlation between carbonate and silicate weathering and arsenic distribution in the order Wells > shallow MBH > deep MBH > shallow CBH > deep CBH. Shallow monitoring boreholes (MBH) appear to mobilize arsenic through silicate weathering and deep MBHs and CBHs generally mobilize arsenic through carbonate weathering, whilst shallow CBHs and wells appear to mobilize arsenic through a combination of carbonate and silicate weathering. There is therefore the need to identify areas with suitable deep aquifers where there is adequate knowledge of the recharge mechanism and the soil profile to determine protected aquifers for location of new boreholes.

Keywords: Arsenic Groundwater Depth Conceptual Model

I. INTRODUCTION

Arsenic can be found in over 200 minerals in the form of arsenate, arsenites, arsenides, sulphides and oxides (Smedley et al., 2002). The concentration of this metalloid in surface water and groundwater is increasing through among others the use of arsenical pesticides, mining, processing, oxidation-reduction of soil minerals and burning of fossil fuels (Ferguson et al., 1972 and Igboamalu et al., 2018). The greatest concentrations of the element tend to occur in sulphide minerals such as arsenopyrite (FeAsS) (Smedley, 1996). Groundwater pollution by arsenic is a serious threat to mankind all over the world (Igboamalu et al., 2017 and Smedley et al., 2007). Studies have linked long-term exposure to arsenic in drinking water to cancer of the bladder, lungs, skin, kidney, liver, and prostate (Anon., 2001).

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