Geochemistry for sustainable development in Africa: Zimbabwe case study

Abstract

Geochemistry is the geology and chemistry concerned with the chemical composition of, and chemical reactions taking place within, the Earth's crust. While the geology and chemistry of Africa is known the chemical reactions that are taking place are not fully documented yet if documented the geochemistry can be used as a tool for sustainable development in Africa. Most of Africa is in tropical and subtropical regions where a long history of chemical weathering takes place thus changing the surface chemistry and making it particularly fragile. A case study from Zimbabwe is presented here to illustrate how geochemistry can be used for sustainable development of Africa. The study assessed tailings dumps' potential to cause environmental problems related to their geochemistry. An overview of the general levels of potential toxic elements in different dump types is given by this study and the types of dumps and mines that are associated with certain risk elements are outlined. As Africa has the largest tropical area of any continent, it is likely to have many chemical weathering taking place thus a need to continuously study its geochemistry. A catalogue of information regarding Zimbabwean tailings dumps and their geochemistry as well as characteristic of immediate environment was constructed as part of a Masters study. This information was used to predict and model possible dispersion and pollution patterns that are likely to result from the tailings dumps found in the country. Possible environmental problems related to the geochemistry of the dumps are outlined. Different stakeholders who may need to redress problems associated with mine tailings dumps in Zimbabwe can use the information gathered during the course of this study. Short-and long-term impacts of the mines and their waste can also be deduced from the information. The results from this research indicate significantly higher levels of potentially toxic elements in the base metals, minor metals, gold, sulphur and platinum group metal dumps compared to the soils around these dumps. The levels most of potentially toxic elements encountered within the dumps during the course of this study have significant implications to the mining industry and particularly to tailings disposal in terms of the potential to pollute the environment. The major output of the study is data that can be used for sustainable development in ways of managing the environment to ensure continual existence of the mining industry in a sustainable way.