Mercury in the Atmosphere

Mercury emissions to the atmosphere due to precious metal mining and processing has been, until very recently, considered to be of relatively little importance compared with direct discharges into soils, tailings and rivers. However, better understanding of the whole production process, emission factors and the total amount of mercury involved has shown that Hg emission to the atmosphere from this type of mining is the most important source of this pollutant to the environment (Pfeiffer and Lacerda 1988; Hacon et al. 1990; Lacerda and Salomons 1991). It was shown in the last chapter that Hg emissions to the atmosphere represent 45 to 87% of the total Hg emitted from precious metal mining and may account for a global input of 200–420 tons year-1. These figures represent a contribution that can reach from 6 to 11% of the global anthropogenic atmospheric emission of mercury to the biosphere of 3550 tons year-1 (Nriagu 1990).