Antarctic winter mercury and ozone depletion events over sea ice
Artikel i vetenskaplig tidskrift, 2016

During atmospheric mercury and ozone depletion events in the springtime in polar regions gaseous elemental mercury and ozone undergo rapid declines. Mercury is quicldy transformed into oxidation products, which are subsequently removed by deposition. Here we show that such events also occur during Antarctic winter over sea ice areas, leading to additional deposition of mercury. Over four months in the Weddell Sea we measured gaseous elemental, oxidized, and particulate-bound mercury, as well as ozone in the troposphere and total and elemental mercury concentrations in snow, demonstrating a series of depletion and deposition events between July and September. The winter depletions in July were characterized by stronger correlations between mercury and ozone and larger formation of particulate-bound mercury in air compared to later spring events. It appears that light at large solar zenith angles is sufficient to initiate the photolytic formation of halogen radicals. We also propose a dark mechanism that could explain observed events in air masses coming from dark regions. Br-2 that could be the main actor in dark conditions was possibly formed in high concentrations in the marine boundary layer in the dark. These high concentrations may also have caused the formation of high concentrations of CHBr3 and CH2I2 in the top layers of the Antarctic sea ice observed during winter. These new findings show that the extent of depletion events is larger than previously believed and that winter depletions result in additional deposition of mercury that could be transferred to marine and terrestrial ecosystems.

elemental mercury

ozone

Antarctica

Ozone

surface

Mercury

Depletion event

springtime depletion

molecular halogens

dissolved gaseous mercury

tropospheric bro

polar sunrise

coastal antarctica

Sea ice

arctic-ocean

Meteorology & Atmospheric Sciences

Environmental Sciences & Ecology

atmospheric mercury

Författare

Michelle Nerentorp

Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

Katarina Gårdfeldt

Kemi och kemiteknik, Energi och material, Oorganisk miljökemi

B. Jourdain

Université Grenoble Alpes

Katarina Abrahamsson

Göteborgs universitet

Anna Granfors

Göteborgs universitet

Martin Ahnoff

Göteborgs universitet

A. Dommergue

Université Grenoble Alpes

G. Mejean

Université Grenoble Alpes

H. W. Jacobi

Université Grenoble Alpes

Atmospheric Environment

1352-2310 (ISSN)

Vol. 129 125-132

Ämneskategorier

Kemi

Miljövetenskap

DOI

10.1016/j.atmosenv.2016.01.023