NASAのインスタグラム(nasa) - 1月16日 03時57分

Vigorous mixing in the air above large cracks in Arctic sea ice that expose seawater to cold polar air pumps atmospheric mercury down to the surface, finds a NASA field campaign. This process can lead to more of the toxic pollutant entering the food chain, where it can negatively affect the health of fish and animals who eat them, including humans.

Scientists measured increased concentrations of mercury near ground level after sea ice off the coast of Barrow, Alaska, cracked, creating open seawater channels called leads. The researchers were in the Arctic for the NASA-led Bromine, Ozone, and Mercury Experiment (BROMEX) in 2012.

The mercury-pumping reaction takes place because open water in a lead is much warmer than the air above it, according to study lead author Chris Moore of the Desert Research Institute, Reno, Nev in a paper reporting the discovery published in Nature on Jan. 15. Because of that temperature difference, the air above the lead churns like the air above a boiling pot.
Almost all of the mercury in the Arctic atmosphere is transported there in gaseous form from sources in areas farther south. Scientists have long known that mercury in the air near ground level undergoes complex chemical reactions that deposit the element on the surface. Once the mercury is completely removed from the air, these reactions stop. However, this newly discovered mixing triggered by leads in the sea ice forces down additional mercury to restart and sustain the reactions.

Image Credit: University of Hamburg, Germany
#ice #nasa #flights #arctic #seaice #mercury #earth #pole #alaska #bromex

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