Determination of heavy metals in water bodies in the Tarkwa and Obuasi mining areas

2009

English

Water is a major pathway through which toxic chemicals such as heavy metals affect plants, animals and man. Gold mining in the study area generates a lot of chemical and other mine wastes, which cause various degrees of environmental damages and constitute a threat to existence human beings, plants, animals and the ecosystem. Chemical wastes generated are soluble in water. Heavy metal pollution from gold mining is difficult to control and unless eliminated or strictly contained in tailing pond, mining remains a major source from which heavy metal pollutants can spread into water bodies and the environment. The long period of mining in the study area has resulted in increased concentrations of heavy metals and other pollutants in water bodies. For example, from 1947 and until 1992, mine effluents have been discharged without restriction into water bodies, soil and air, thereby resulting in the degeneration of the environment (Carboo, 1997; Tufour, 1997 and Tsidzi, 1993). According to Amegbey and Adimado (2003), there have been 11 officially reported cyanide spillages between 1989 and 2003 in the study areas. Recent accounts in the media about cyanide spillages as well as the release of other hazardous chemicals into water bodies from mining operations have necessitated assessment of the levels of heavy metals in water bodies in the study area. Whereas cyanide species in water bodies are photo – degradable, heavy metals on the other hand are not photo – degradable and persist in the environment. The Ghanaian society is constantly faced with three fundamental questions:  What are the risks associated with exposure to heavy metals in water bodies in the study area?  How serious are the exposure?  How well can it be estimated? Obtaining answers to the above questions provide strong justification for a study of this nature to assess scientifically the quality of water bodies in Tarkwa and Obuasi mining areas. The study areas have long histories of mining activities, which have resulted in the release of toxic chemicals into the environment and water bodies. The objectives of this study are therefore:  Determine the levels of heavy metals in streams and rivers in the Obuasi and Tarkwa mining areas.  Determine the levels of heavy metals in alternate source of drinking that has been provided for communities whose source of drinking water have been impacted upon negatively by mining activities in the study areas.  Compare the levels of heavy metals in streams and rivers in the areas with permissible levels of heavy metals in streams and rivers prescribed by GEPA (Ghana Environmental Protection Agency), USEPA (US Environmental Protection Agency) and WHO (World Health Organisation).  To recommend to government and other stakeholders the need to provide alternate potable water for the inhabitants should mining operations in the area cease.

Obiri, S.