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It’s been difficult to explain patterns of toxic mercury in some parts of the world, such as why there’s so much of the toxin deposited into ecosystems from the air in the southeastern United States, even upwind of usual sources.
A new analysis led by researchers at the University of Colorado Boulder shows that one key to understanding mercury’s strange behavior may be the unexpected reactivity of naturally occurring halogen compounds from the ocean.
“Atmospheric chemistry involving bromine and iodine is turning out to be much more vigorous than we expected,” said CU-Boulder atmospheric chemist Rainer Volkamer, the corresponding author of the new paper published in the Proceedings of the National Academy of Sciences. “These halogen reactions can turn mercury into a form that can rain out of the air onto the ground or into oceans” up to 3.5 times faster than previously estimated, he said.
The new chemistry that Volkamer and his colleagues have uncovered, with the help of an innovative instrument developed at CU-Boulder, may also help scientists better understand a longstanding limitation of global climate models. Those models have difficulty explaining why levels of ozone, a greenhouse gas, were so low before the Industrial Revolution.
“The models have been largely untested for halogen chemistry because we didn’t have measurements in the tropical free troposphere before,” Volkamer said. “The naturally occurring halogen chemistry can help explain that low ozone because more abundant halogens destroy ozone faster than had previously been realized.”
Ocean wave and spray image via Shutterstock.
Read more at: http://www.colorado.edu/news/releases/2015/06/29/atmospheric-mysteries-unraveling#sthash.Sg2W8VgV.dpuf
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