A while back my daughter was busy with a project concerning the Inuit people, and to give her an idea of what living in the high North looked like, we watched Robert J. Flaherty's epic 1922 documentary Nanook of the North. I was doubly interested because I had been reading about how the Inuit diet (high in animal fats) made cancer and coronary diseases practically non-existent until modern processed foods were introduced.
As unhealthy as processed foods may be, reverting to the traditional diet would probably be suicide. It has been known for quite a while that dioxins and other toxic substances from all over the world are accumulating in the Arctic food web, but now it appears that the decline in Arctic sea ice is causing a direct increase in another toxic substance: mercury.
Last week a paper was published in the Journal of Geophysical research by Son V. V. Nghiem et al., called Field and satellite observations of the formation and distribution of Arctic atmospheric bromine above a rejuvenated sea ice cover. From the press release:
Drastic reductions in Arctic sea ice in the last decade may be intensifying the chemical release of bromine into the atmosphere, resulting in ground-level ozone depletion and the deposit of toxic mercury in the Arctic, according to a new NASA-led study.
The connection between changes in the Arctic Ocean's ice cover and bromine chemical processes is determined by the interaction between the salt in sea ice, frigid temperatures and sunlight. When these mix, the salty ice releases bromine into the air and starts a cascade of chemical reactions called a "bromine explosion." These reactions rapidly create more molecules of bromine monoxide in the atmosphere. Bromine then reacts with a gaseous form of mercury, turning it into a pollutant that falls to Earth's surface.
Bromine also can remove ozone from the lowest layer of the atmosphere, the troposphere. Despite ozone's beneficial role blocking harmful radiation in the stratosphere, ozone is a pollutant in the ground-level troposphere.
A team from the United States, Canada, Germany, and the United Kingdom, led by Son Nghiem of NASA's Jet Propulsion Laboratory in Pasadena, Calif., produced the study, which has been accepted for publication in the Journal of Geophysical Research-Atmospheres. The team combined data from six NASA, European Space Agency and Canadian Space Agency satellites, field observations and a model of how air moves in the atmosphere to link Arctic sea ice changes to bromine explosions over the Beaufort Sea, extending to the Amundsen Gulf in the Canadian Arctic.
"Shrinking summer sea ice has drawn much attention to exploiting Arctic resources and improving maritime trading routes," Nghiem said. "But the change in sea ice composition also has impacts on the environment. Changing conditions in the Arctic might increase bromine explosions in the future."
The upper panel shows a bromine explosion observed by scientists at the University of Bremen on March 14, 2008 over Alaska and the Beaufort Sea. The lower panel shows sea ice cover at the time, as measured by NASA's QuikScat spacecraft. Image credit: NASA-JPL/Caltech/University of Bremen/University of Washington.
Dioxins, flame retardants, Bisphenol A, bromine 'explosions', mercury. What a legacy we leave behind...