Anthropogenic mercury emissions in South Africa: Coal combustion in power plants

South Africa is regarded as a country with the 2nd highest mercury (Hg) emissions in the world. This assumption is based on estimates of total Hg emissions derived primarily from gold mining and coal combustion. The potential sources of Hg to the South African environment were assessed by focussing particularly on coal combustion at the countryʹs coal-fired power plants. Mercury emission estimates were based on the total amount of coal burned in all power plants per year (112.3 Mt y−1), the Hg content of South African coals (0.2 ppm) and the emission control devices used in each power plant. Results indicate that Hg emissions arising from South Africaʹs coal-fired power plants (ranging between 2.6 and 17.6 tonnes y−1, with an estimated average emission of 9.8 tonnes y−1) are significantly lower than suggested in the literature (approximately 50 tonnes y−1). The calculated emission factor (ranging between 0.02 and 0.16 g Hg tonne−1 coal burned) and per capita estimates (0.24 g Hg person−1 y−1 R−1, where R is the fraction of total electricity generated from coal) fall within the range of values reported for Hg inventories derived in other countries and indicate that Hg emission estimates for coal-fired power plants presented in this paper are more reliable than those published previously.