Year-round records of bulk and size-segregated aerosol composition in central Antarctica (Concordia site) – Part 1: Fractionation of sea-salt particles
Multiple year-round records of bulk and size-segregated composition of aerosol were obtained at the inland site of Concordia located at Dome C in East Antarctica. In parallel, sampling of acidic gases on denuder tubes was carried out to quantify the concentrations of HCl and HNO<sub>3</...
Main Authors: | , , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-11-01
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Series: | Atmospheric Chemistry and Physics |
Online Access: | https://www.atmos-chem-phys.net/17/14039/2017/acp-17-14039-2017.pdf |
Summary: | Multiple year-round records of bulk and size-segregated
composition of aerosol were obtained at the inland site of Concordia located
at Dome C in East Antarctica. In parallel, sampling of acidic gases on
denuder tubes was carried out to quantify the concentrations of HCl and
HNO<sub>3</sub> present in the gas phase. These time series are used to examine
aerosol present over central Antarctica in terms of chloride depletion
relative to sodium with respect to freshly emitted sea-salt aerosol as well
as depletion of sulfate relative to sodium with respect to the composition
of seawater. A depletion of chloride relative to sodium is observed over
most of the year, reaching a maximum of ∼ 20 ng m<sup>−3</sup> in
spring when there are still large sea-salt amounts and acidic components
start to recover. The role of acidic sulfur aerosol and nitric acid in
replacing chloride from sea-salt particles is here discussed. HCl is found
to be around twice more abundant than the amount of chloride lost by
sea-salt aerosol, suggesting that either HCl is more efficiently transported
to Concordia than sea-salt aerosol or re-emission from the snow pack over the
Antarctic plateau represents an additional significant HCl source. The
size-segregated composition of aerosol collected in winter (from 2006 to
2011) indicates a mean sulfate to sodium ratio of sea-salt aerosol present
over central Antarctica of 0.16 ± 0.05, suggesting that, on average,
the sea-ice and open-ocean emissions equally contribute to sea-salt aerosol
load of the inland Antarctic atmosphere. The temporal variability of the
sulfate depletion relative to sodium was examined at the light of air mass
backward trajectories, showing an overall decreasing trend of the ratio
(i.e., a stronger sulfate depletion relative to sodium) when air masses
arriving at Dome C had traveled a longer time over sea ice than over
open ocean. The findings are shown to be useful to discuss sea-salt ice
records extracted at deep drilling sites located inland Antarctica. |
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ISSN: | 1680-7316 1680-7324 |