Multi-year record of atmospheric and snow surface nitrate in the central Antarctic plateau

• Published in: Chemosphere
• Main Author: Scarchilli, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier Ltd 2017
• Subjects: Aerosol; Antarctica; Nitrate; Dome C; Stratosphere-troposphere exchange; Surface snow; Antarc*; Antarctic
• Online Access: https://hdl.handle.net/20.500.12079/1766; https://doi.org/10.1016/j.chemosphere.2016.12.143; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011890868&doi=10.1016%2fj.chemosphere.2016.12.143&partnerID=40&md5=7cb7fb5a35d653bf45712dcbdef22588

Continuous all year-round samplings of atmospheric aerosol and surface snow at high (daily to 4-day) resolution were carried out at Dome C since 2004-05 to 2013 and nitrate records are here presented. Basing on a larger statistical data set than previous studies, results confirm that nitrate seasonal pattern is characterized by maxima during austral summer for both aerosol and surface snow, occurring in-phase with solar UV irradiance. This temporal pattern is likely due to a combination of nitrate sources and post-depositional processes whose intensity usually enhances during the summer. Moreover, it should be noted that a case study of the synoptic conditions, which took place during a major nitrate event, showed the occurrence of a stratosphere-troposphere exchange. The sampling of both matrices at the same time with high resolution allowed the detection of a an about one-month long recurring lag of summer maxima in snow with respect to aerosol. This result can be explained by deposition and post-deposition processes occurring at the atmosphere-snow interface, such as a net uptake of gaseous nitric acid and a replenishment of the uppermost surface layers driven by a larger temperature gradient in summer. This hypothesis was preliminarily tested by a comparison with surface layers temperature data in the 2012-13 period. The analysis of the relationship between the nitrate concentration in the gas phase and total nitrate obtained at Dome C (2012-13) showed the major role of gaseous HNO3 to the total nitrate budget suggesting the need to further investigate the gas-to-particle conversion processes. © 2017 Elsevier Ltd