The hydrochemistry of water resources in selected mining communities in Tarkwa

Abstract Tarkwa is one of the most heavily mined localities in Ghana. Mining activities are associated with the release of toxic chemicals into the environment which pollute water resources in mining communities within the catchment of mines. The study was undertaken in communities within the catchment of three mining companies in Tarkwa to find out the impact of mining on the water quality of these settlements. The research was conducted by taken water samples of both surface and groundwater within these communities for laboratory analysis using Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectrophotometer (AAS) to determine the concentration levels of elements in the water. The analysis showed that, concentration levels of certain elements namely, iron, cadmium, copper, cyanide, arsenic and zinc were beyond allowable limits of World Health Organization (WHO), Ghana Standards Board (GSB) and Ghana Water Company (GWC) guidelines for drinking water in certain samples confirming the communities' perception that, their water resources are polluted owing to the mining activities. Excess levels of iron and arsenic were found in 65% of samples, cadmium 23%, copper 58%, cyanide 12%, and zinc 42%. Concentration levels of 3.75 mg/l and 1.76 mg/l of iron and arsenic were detected in certain samples. Maximum concentration level for cadmium was 0.37 mg/l, copper 7.45 mg/l, cyanide 8 mg/l and zinc 10.2 mg/l. Toxicity level of other elements such as mercury, lead, chloride, nitrates and others was low. Except mercury and cyanide whose presence in the environment is introduced by mining activities, the presence of other elements in water resources is mobilized from weathered rocks of the underlying geology.