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Insights on nitrate sources at Dome C (East Antarctic Plateau) from multi-year aerosol and snow records

TitoloInsights on nitrate sources at Dome C (East Antarctic Plateau) from multi-year aerosol and snow records
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione2014
AutoriTraversi, R., Udisti R., Frosini D., Becagli S., Ciardini Virginia, Funke B., Lanconelli C., Petkov B., Scarchilli Claudio, Severi M., and Vitale V.
RivistaTellus, Series B: Chemical and Physical Meteorology
Volume66
ISSN02806509
Parole chiaveaerosol composition, aerosol formation, Antarctic plateau, antarctica, boundary layer, Chemical composition, dome, East Antarctica, ice cover, irradiance, nitrate, Snow, spatial resolution
Abstract

Here we present the first multi-year record of nitrate in the atmospheric aerosol (2005-2008) and surface snow (2006-08) from central Antarctica. PM10 and size-segregated aerosol, together with superficial snow, have been collected all year-round at high resolution (daily for all the snow samples and for most of aerosol samples) at Dome C since the 2004/05 field season and analysed for main and trace ionic markers. The suitability of the sampling location in terms of possible contamination from the base is shown in detail. In spite of the relevance of nitrate in Antarctic atmosphere, both for better understanding the chemistry of N cycle in the plateau boundary layer and for improving the interpretation of long-term nitrate records from deep ice core records, nitrate sources in Antarctica are not well constrained yet, neither in extent nor in timing. A recurring seasonal pattern was pointed out in both aerosol and snow records, showing summer maxima and winter minima, although aerosol maxima lead the snow ones of 1-2 months, possibly due to a higher acidity in the atmosphere in mid-summer, favouring the repartition of nitrate as nitric acid and thus its uptake by the surface snow layers. On the basis of a meteorological analysis of one major nitrate event, of data related to PSC I extent and of irradiance values, we propose that the high nitrate summer levels in aerosol and snow are likely due to a synergy of enhanced source of nitrate and/or its precursors (such as the stratospheric inputs), higher solar irradiance and higher oxidation rates in this season. Moreover, we show here a further evidence of the substantial contribution of HNO3/NOx re-emission from the snowpack, already shown in previous works, and which can explain a significant fraction of atmospheric nitrate, maintaining the same seasonal pattern in the snow. As concerning snow specifically, the presented data suggest that nitrate is likely to be controlled mainly by atmospheric processes, not on the daily timescale but rather on the seasonal one. © 2014 R. Traversi et al.

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URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-84930959465&doi=10.3402%2ftellusb.v66.22550&partnerID=40&md5=4b8bbcc6b4127e45126f14a9bf5defe8
DOI10.3402/tellusb.v66.22550
Citation KeyTraversi2014