Emission inventories of atmospheric mercury from anthropogenic sources

Although quite extensive information exists on environmental and health effects of mercury and its behavior in the environment, much less information is available on the emission fluxes of the element, Preliminary studies conclude that on the global scale the Hg emission to the air is comparable with direct inputs of the element to the aquatic environment and are almost a half of the direct releases to the terrestrial environment, Thus, the atmosphere is an important pathway for mercury cycling in the environment. Globally, combustion of fossil fuels to produce electricity and heat is the major source of atmospheric emissions of Hg. Both national and regional emission inventories indicate that the combustion of fuels, particularly coal, emits more than half of the atmospheric Hg in Europe. Major portion of Hg emissions from combustion of fuels is in a gaseous phase. In the combustion zone Hg present in coal or other fossil fuels evaporates in elemental form and then most likely a portion of it is oxidized while in the flue gases. The oxidized forms of Hg can be retained in modern flue gas cleaning systems. Refuse incineration seems to be the second largest source of Hg emissions to the atmosphere. Emission generation process for He during the incineration of wastes is similar to that during combustion of fossil fuels. However, more Hg in the oxidized form is expected from incinerators due to the higher content of chlorine in the wastes compared to fossil fuels.