Mercury from combustion sources: A review of the chemical species emitted and their transport in the atmosphere

TLDR: In this article, it was shown that emissions of coal combustion sources are approximately 20-50% elemental and 50-80% divalent mercury (HgCl2) and that the partitioning of mercury in flue gas between the elemental and divalent forms may depend on the concentration of particulate carbon, HCl and other pollutants in stack emissions.

Abstract: Different species of mercury have different physical/chemical properties and thus behave quite differently in air pollution control equipment and in the atmosphere. In general, emissions of mercury from coal combustion sources are approximately 20–50% elemental mercury (Hg°) and 50–80% divalent mercury (Hg(II)), which may be predominantly HgCl2. Emissions of mercury from waste incinerators are approximately 10–20% Hg° and 75–85% Hg(II). The partitioning of mercury in flue gas between the elemental and divalent forms may be dependent on the concentration of particulate carbon, HCl and other pollutants in the stack emissions. The emission of mercury from combustion facilities depends on the species in the exhaust stream and the type of air pollution control equipment used at the source. Air pollution control equipment for mercury removal at combustion facilities includes activated carbon injection, sodium sulfide infection and wet lime/limestone flue gas desulfurization.