Assessing the seasonal dynamics of nitrate and sulfate aerosols at the South Pole utilizing stable isotopes

Journal of Geophysical Research D: Atmospheres
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Abstract

Atmospheric nitrate (NO3 = particulate NO3 + gas‐phase nitric acid [HNO3]) and sulfate (SO42−) are key molecules that play important roles in numerous atmospheric processes. Here, the seasonal cycles of NO3 and total suspended particulate sulfate (SO42−(TSP)) were evaluated at the South Pole from aerosol samples collected weekly for approximately 10 months (26 January to 25 October) in 2002 and analyzed for their concentration and isotopic compositions. Aerosol NO3 was largely affected by snowpack emissions in which [NO3] and δ15N(NO3) were highest (49.3 ± 21.4 ng/m3n = 8) and lowest (−47.0 ± 11.7‰, n = 5), respectively, during periods of sunlight in the interior of Antarctica. The seasonal cycle of Δ17O(NO3) reflected tropospheric chemistry year‐round with lower values observed during sunlight periods and higher values observed during dark periods, reflecting shifts from HOx‐ to O3‐dominated oxidation chemistry. SO42−(TSP)concentrations were highest during austral summer and fall (86.7 ± 73.7 ng/m3n = 18) and are indicated to be derived from dimethyl sulfide (DMS) emissions, as δ34S(SO42−)(TSP)values (18.5 ± 1.0‰, n = 10) were similar to literature δ34S(DMS) values. The seasonal cycle of Δ17O(SO42−)(TSP) exhibited minima during austral summer (0.9 ± 0.1‰, n = 5) and maxima during austral fall (1.3 ± 0.3‰, n = 6) and austral spring (1.6 ± 0.1‰, n = 5), indicating a shift from HOx‐ to O3‐dominated chemistry in the atmospheric derived SO42−component. Overall, the budgets of NO3 and SO42−(TSP) at the South Pole were complex functions of transport, localized chemistry, biological activity, and meteorological conditions, and these results will be important for interpretations of oxyanions in ice core records in the interior of Antarctica.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Assessing the seasonal dynamics of nitrate and sulfate aerosols at the South Pole utilizing stable isotopes
Series title Journal of Geophysical Research D: Atmospheres
DOI 10.1029/2019JD030517
Volume 124
Issue 14
Year Published 2019
Language English
Publisher AGU
Contributing office(s) National Research Program - Eastern Branch, WMA - Earth System Processes Division
Description 17 p.
First page 8161
Last page 8167
Other Geospatial Antarctica, South Pole