ARL News

Mercury in Air – New Reports Are Questioning Earlier Assumptions


July 12, 2004

New observations of the chemistry of power plant plumes raise questions about proposed mercury emission control strategies.

On a global scale, coal fired power plants are the largest source of mercury in the air. They emit mercury in two main forms, relatively unreactive elemental mercury vapor and compounds that are far more reactive. It is the reactive compounds that most rapidly deposit to the surface and get entrained into the food chain. If these emissions of reactive gaseous mercury were eliminated, it has been assumed that the level of the reactive mercury compounds in air immediately downwind would be reduced and hence that the loadings to local ecosystems would also be reduced. However, at a recent meeting (in Slovenia) several papers reported the finding that the reactive mercury emitted in power plant plumes is quickly converted to the elemental (unreactive) form. The results of studies to answer the questions that then arise will determine which of several alternative control strategies would work best. The problem will likely require international attention, as well as regional controls.

These reports are exceedingly timely, since an integrated Mercury program is presently being constructed as a part of the PBA/PPBES process. Clearly, there is great need for the kind of research that OAR scientists are promoting.

Contact information: Mark Cohen
Phone: (301) 713-0295