Editor’s comments

A bromine explosion occurred on March 13, 2008 across the western Northwest Territories in Canada. In the image the bromine explosion is represented in the foreground by the red-orange areas, while the green shades at high altitudes on the mountains represent areas where there was no increase in bromine.

Salty sea-ice and sunlight results in the release of bromine into the atmosphere which initiates a sequence of chemical reactions called a “bromine explosion.” A bromine explosion rapidly creates bromine monoxide in the atmosphere. Bromine monoxide catalyzes the destruction of ozone and reacts with gaseous mercury leading to the deposition of solid toxic mercury on land, snow and ice.

A NASA team used the topography of mountain ranges in Alaska and Canada as a ruler to measure the altitude at which the explosions took place. Their research has shown that the Alaskan Brooks Range and the Canadian Richardson and Mackenzie mountains stopped bromine from moving into Alaska’s interior. Most of these mountains are lower than 2,000 meters, so it was determined that bromine explosions are confined to the lower troposphere.

The researchers related the bromine release to sources on the surface and then tied bromine release to recent changes in Arctic sea ice that have led to a much saltier sea ice surface. Young sea-ice is much saltier than older sea-ice (Over time physical processes reduce the concentration of salts.) providing more salt sources to drive bromine releases. Young sea-ice also contains more frost flowers, clumps of ice crystals up to four times saltier than ocean waters. Because of the trends in the Arctic to younger sea-ice it is projected that bromine explosions will increase in the Arctic leading to reduced ground level ozone and more toxic mercury deposition.
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, D00S05, 15 PP., 2012