Sources of Arsenic Distribution at Obuasi in Ghana

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

Sources of Arsenic Distribution at Obuasi in Ghana

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

Abstract – There have been various studies to establish the potential sources of arsenic responsible for pollution of surface water and groundwater in the Obuasi Municipality of Ghana. This study seeks to provide better understanding of the identified sources and their characteristics in the study area. In the study rock and soil samples were taken from identified active and inactive arsenic storage structures for analyses of their photomicrographs and selected metal content. Results of photo-micrographic study indicate geologic features of arsenic source minerals such as pyrite, arsenopyrite in different states of oxidation. Other minerals present were pyrrhotite, chalcopyrite, sphalerite, stibnite and galena. It suggests significant potential for acid-mine drainage in the study area. Majority of gangue minerals contain acid-buffering or carbonate-bearing rocks/alterations relevant to control the AMD effect they generate whilst others do not and will therefore rely on the acid-buffering effect of the surface water or groundwater constituents. Arsenic and trace element analysis of tailings dams and tailings footprints around surface water and groundwater suggests that the oxidation of arsenic rich minerals reduces as you move away from the water sources and underscores the importance of water to the oxidation and mobility of arsenic in the study area. Acid base accounting of tailings material from Anglogold Ashanti Obuasi Mine Oxide Treatment Plant (OTP) and Sulphide Treatment Plant (STP) confirms the likelihood of acid mine drainage from the tails of the OTP and STP.

Keywords – Arsenic Photomicrograph Sources Obuasi

I. INTRODUCTION

Legal and illegal exploitation for gold combined with the natural geochemical dispersion from exposed arsenic mineralization has resulted in arsenic contaminated water, animals, plants and soils in the Obuasi Municipality ([1], [2], [3], [4], [5], [6], [7] and [8]). Rock and soil are the main sources of arsenic which are eventually recycle into plants, animals, humans, surface water and groundwater ([2], [9] and [10]). The study area has many government regulated active and inactive arsenic storage sites composed of rock waste dumps, tailings dams, arsenic trioxide storage sites, heap leach sites, some visible dumped rock sheathing for roads and other constructional activities ([3] and [11]). There are also many illegal mining sites scattered across the Obuasi community ([12], [13], [14], [15] and [16]). Studies have identified relationship between arsenic and other tracers in clarified surface water and groundwater [4]. However, its filtration residue and its host mineralogy in areas of close proximity to mining related arsenic storage infrastructure in Obuasi Municipality has not been well studied. This study seeks to provide understanding of the sources and distribution of arsenic and its relationship

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