Forest fires and other blazes in the United States likely release about 30 percent as much mercury as the nation's industrial sources, according to initial estimates in a new study by scientists at the National Center for Atmospheric Research (NCAR). Fires in Alaska, California, Oregon, Louisiana, and Florida emit particularly large quantities of the toxic metal, and the Southeast emits more than any other region, according to the research. The mercury released by forest fires originally comes from industrial and natural sources.
The paper estimates that fires in the continental United States and Alaska release about 44 metric tons of mercury into the atmosphere every year. It is the first study to estimate mercury emissions for each state, based on a new computer model developed at NCAR. The authors caution that their estimates for the nation and for each state are preliminary and are subject to a 50 percent or greater margin of error. A metric ton is about 10% larger than a U.S. ton.
Mercury emissions from fires. This map shows the annual average (in metric tons) of mercury released by fires for every state except Hawaii. The estimates are based on fires from 2002 to 2006. (Credit: Illustration by Steve Deyo, Copyright UCAR)