Publikationsdatum:
2018-11-23
Beschreibung:
During the I997-98 Italian Antarctic Programme (PNRA) summer season, two snow pits were
dug 3km north-westward of the ltalian-French Dome C Station (East Antarctica, 75o 09'S, 123o 06'E,
3200m a.s.l.) and the EPICA project drilling site. These 4 m depth pits were done upwind of the station
to avoid the risk of pollution. In the first pit, after cleaning of walls, a high resolution sampling was
carried out for chemical (anions, cations, organic acids), stable isotope ( d 180 and d D), tritium and
dust (concentration, size distribution, AI concentration) measurements. In the second pit, dug 50cm
apart, visual stratigraphy was done.
The concentration/depth profiles and any eventual correlation between chemical components
were examined to obtain environmental information about primary and secondary aerosol sources,
transport phenomena and any evidence of relevant trends in the temporal series of some components.
Particular attention was spent on the relative contribution of sea spray components (Na+, Cl-, Mg2+)
and substances from biogenic origin (nssSO42- and MSA) to atmospheric aerosol. Using Na+ and MSA
as source tracers, fractionating phenomena induced variations of CI-/Na+ and nssSO42-/MSA ratios
were valued. nssSO42-/MSA relationship with MSA reveals the importance of long range transport
effects and the presence of other nssSO42- sources. Temporal data series for Ca2+, K+, No3-, F- and
some short chain carboxylic acids are also reported. For almost all the components ng/g or sub-ng/g
concentration levels were found, as expected for a station located at a very long distance from the most
part of aerosol sources and at high altitude. Tritium analyses were carried out in order to identify the
peak related to the thermonuclear tests performed in the atmosphere in the early sixties as a reference
horizon for dating purpose. The seasonal signal in the stable isotopes was not observed due to the low
accumulation of this site, but nevertheless the main trends were compared to other Antarctic sites and
to temperature records available from the main East Antarctica automatic weather stations. The dust
concentration, size distribution (Particles Counter) and AI (Atomic Absorption) measurements show
records of continental influences on the Dome C insoluble aerosols.
The very low annual accumulation rate, 3 to 3.5 cm (W.E.) and, probable, wind erosion are the
main reasons of the absence of seasonal variations. Because of this limitation, of more interest is the
correlation of the measured records with the visual stratigraphy. The main topics from these pits
measurements can provide: 1) the sutdy of the last tens years of atmospheric deposition in the Dome C
area, 2) define the atmosphere-snow transport processes, also on the comparison with EPICA ice core,
3) identification of primary and secondary sources at this site.
Repository-Name:
EPIC Alfred Wegener Institut
Materialart:
Conference
,
notRev
Format:
application/pdf
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