TY - JOUR
T1 - Isotopic constraints on sources, production, and phase partitioning for nitrate in the atmosphere and snowfall in coastal East Antarctica
AU - Shi, Guitao
AU - Li, Chuanjin
AU - Li, Yilan
AU - Chen, Zhenlou
AU - Ding, Minghu
AU - Ma, Hongmei
AU - Jiang, Su
AU - An, Chunlei
AU - Guo, Jingxue
AU - Sun, Bo
AU - Hastings, Meredith G.
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2022/1/15
Y1 - 2022/1/15
N2 - Atmospheric samples and snowfall collected in coastal East Antarctica over two years are used to investigate the sources, production of atmospheric nitrate (NO3−) and its link with snowfall NO3− based upon the isotopic composition of NO3− (δ15N, δ18O, and Δ17O). Snowfall and the atmosphere show similar seasonal trends in concentrations and isotopic composition of NO3−. In summer, atmospheric NO3− is closely associated with snowpack emissions of NOx from photolysis of snow NO3−. In winter, linear relationships between δ15N and δ18O (or Δ17O) of NO3− in both snowfall and the atmosphere indicate mixing between stratospheric inputs and tropospheric sources contributing to NO3−, with stratospheric inputs contributing 55±21% of the atmospheric NO3− budget. The linear relationships suggest that the lower limits of δ15N, δ18O, and Δ17O of stratospheric-sourced NO3− are close to ∼18, ∼120, and ∼45‰, respectively. Concentration correlates well with the isotopic composition of NO3− in winter, indicating less variable contribution of tropospheric sources. A significant linear correlation between δ18O and Δ17O of NO3− suggests a mix of oxidation processes by O3 and H2O/OH which can influence NOx cycling and the production of NO3−. Lower values of Δ17O of atmospheric NO3− were observed during O3 depletion events in September, suggesting that oxygen isotopes of NO3− could be more sensitive to the changes in surface O3 compared to BrO concentrations. Oxygen isotopic composition of NO3− in snowfall is close to that of the atmosphere throughout the year, suggesting that snowfall NO3− can relay information on oxidative chemistry of NOx in the atmosphere. Snowfall δ15N is close in value to that in the atmosphere during winter, but ∼20‰ higher than that in the atmosphere during summer, possibly associated with seasonal changes in the gas-aerosol partitioning of atmospheric NO3−. This suggests that the interpretation of δ15N in snow needs to consider seasonal changes in sources and chemistry.
AB - Atmospheric samples and snowfall collected in coastal East Antarctica over two years are used to investigate the sources, production of atmospheric nitrate (NO3−) and its link with snowfall NO3− based upon the isotopic composition of NO3− (δ15N, δ18O, and Δ17O). Snowfall and the atmosphere show similar seasonal trends in concentrations and isotopic composition of NO3−. In summer, atmospheric NO3− is closely associated with snowpack emissions of NOx from photolysis of snow NO3−. In winter, linear relationships between δ15N and δ18O (or Δ17O) of NO3− in both snowfall and the atmosphere indicate mixing between stratospheric inputs and tropospheric sources contributing to NO3−, with stratospheric inputs contributing 55±21% of the atmospheric NO3− budget. The linear relationships suggest that the lower limits of δ15N, δ18O, and Δ17O of stratospheric-sourced NO3− are close to ∼18, ∼120, and ∼45‰, respectively. Concentration correlates well with the isotopic composition of NO3− in winter, indicating less variable contribution of tropospheric sources. A significant linear correlation between δ18O and Δ17O of NO3− suggests a mix of oxidation processes by O3 and H2O/OH which can influence NOx cycling and the production of NO3−. Lower values of Δ17O of atmospheric NO3− were observed during O3 depletion events in September, suggesting that oxygen isotopes of NO3− could be more sensitive to the changes in surface O3 compared to BrO concentrations. Oxygen isotopic composition of NO3− in snowfall is close to that of the atmosphere throughout the year, suggesting that snowfall NO3− can relay information on oxidative chemistry of NOx in the atmosphere. Snowfall δ15N is close in value to that in the atmosphere during winter, but ∼20‰ higher than that in the atmosphere during summer, possibly associated with seasonal changes in the gas-aerosol partitioning of atmospheric NO3−. This suggests that the interpretation of δ15N in snow needs to consider seasonal changes in sources and chemistry.
KW - Antarctica
KW - atmosphere
KW - nitrate
KW - nitrogen and oxygen isotopes
KW - snowfall
UR - https://www.scopus.com/pages/publications/85119591555
U2 - 10.1016/j.epsl.2021.117300
DO - 10.1016/j.epsl.2021.117300
M3 - 文章
AN - SCOPUS:85119591555
SN - 0012-821X
VL - 578
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
M1 - 117300
ER -