Nitrate deposition and preservation in the snowpack along a traverse from coast to the ice sheet summit (Dome A) in East Antarctica

• Published in: The Cryosphere
• Main Authors: Shi, Guitao, Hastings, Meredith G., Yu, Jinhai, Ma, Tianming, Hu, Zhengyi, An, Chunlei, Li, Chuanjin, Ma, Hongmei, Jiang, Su, Li, Yuansheng
• Format: Text
• Language: English
• Published: 2019
• Subjects: Antarctic; East Antarctica; Antarc*; Antarctica; ice core; Ice Sheet
• Online Access: https://doi.org/10.5194/tc-12-1177-2018; https://tc.copernicus.org/articles/12/1177/2018/

Antarctic ice core nitrate (NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="5c4cefaf8b78d41c1ce2f2ef151f712f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00001.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00001.png"/></svg:svg> ) can provide a unique record of the atmospheric reactive nitrogen cycle. However, the factors influencing the deposition and preservation of NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="53e1f98be2cdf70dbe180d95894fc6b5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00002.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00002.png"/></svg:svg> at the ice sheet surface must first be understood. Therefore, an intensive program of snow and atmospheric sampling was made on a traverse from the coast to the ice sheet summit, Dome A, East Antarctica. Snow samples in this observation include 120 surface snow samples (top ∼ 3 cm), 20 snow pits with depths of 150 to 300 cm, and 6 crystal ice samples (the topmost needle-like layer on Dome A plateau). The main purpose of this investigation is to characterize the distribution pattern and preservation of NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="0723f17b5be9fc41c36a5585631feb47"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00003.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00003.png"/></svg:svg> concentrations in the snow in different environments. Results show that an increasing trend of NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="8c72af1edd6d67ed562efcaf5163d22b"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00004.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00004.png"/></svg:svg> concentrations with distance inland is present in surface snow, and NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a6a4c5911a740e8377438efb607d4b86"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00005.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00005.png"/></svg:svg> is extremely enriched in the topmost crystal ice (with a maximum of 16.1 µ eq L −1 ) . NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="1933cd4f78557ae19e1c84fa4d0b5473"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00006.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00006.png"/></svg:svg> concentration profiles for snow pits vary between coastal and inland sites. On the coast, the deposited NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="78ed0f7e81615226176402cdd6a1afd5"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00007.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00007.png"/></svg:svg> was largely preserved, and the archived NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M11" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="fa1148a5a7ab62133104fb46bf612014"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00008.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00008.png"/></svg:svg> fluxes are dominated by snow accumulation. The relationship between the archived NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ee54bb0fff66afdafaf51bed1fde360d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00009.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00009.png"/></svg:svg> and snow accumulation rate can be depicted well by a linear model, suggesting a homogeneity of atmospheric NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="a192f22c747584054322d55d69a940ca"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00010.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00010.png"/></svg:svg> levels. It is estimated that dry deposition contributes 27–44 % of the archived NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="ad57fe4a8dcf7ebabf2d1e48d90b5292"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00011.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00011.png"/></svg:svg> fluxes, and the dry deposition velocity and scavenging ratio for NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M15" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="9f81e901bf06635e082f559a787da68a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00012.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00012.png"/></svg:svg> were relatively constant near the coast. Compared to the coast, the inland snow shows a relatively weak correlation between archived NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M16" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="06954914259a113e7faaa0d01a8ee756"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00013.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00013.png"/></svg:svg> and snow accumulation, and the archived NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="5a2143864edd3f7cf8f1639018917994"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00014.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00014.png"/></svg:svg> fluxes were more dependent on concentration. The relationship between NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M18" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="2a83a52cafded6cc529076279999d0cd"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00015.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00015.png"/></svg:svg> and coexisting ions (nssSO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M19" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="49798bc14746e7788afe38c7f4bc425f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00016.svg" width="13pt" height="17pt" src="tc-12-1177-2018-ie00016.png"/></svg:svg> , Na + and Cl − ) was also investigated, and the results show a correlation between nssSO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M22" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">4</mn><mrow><mn mathvariant="normal">2</mn><mo>-</mo></mrow></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="13pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="d290f1661057ae2dbc6fb8878fe6c5e2"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00017.svg" width="13pt" height="17pt" src="tc-12-1177-2018-ie00017.png"/></svg:svg> (fine aerosol particles) and NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M23" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d4917cb251612ae03efebb0a66479930"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00018.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00018.png"/></svg:svg> in surface snow, while the correlation between NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M24" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d615913ec88b34ee0c05b0f0374db64d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00019.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00019.png"/></svg:svg> and Na + (mainly associated with coarse aerosol particles) is not significant. In inland snow, there were no significant relationships found between NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M26" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d96e0e0e6a6172a7d34ac185b1d0a8a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00020.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00020.png"/></svg:svg> and the coexisting ions, suggesting a dominant role of NO <math xmlns="http://www.w3.org/1998/Math/MathML" id="M27" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mn mathvariant="normal">3</mn><mo>-</mo></msubsup></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="9pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="d4f68d92324ab64740c52d46a6e06853"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-12-1177-2018-ie00021.svg" width="9pt" height="16pt" src="tc-12-1177-2018-ie00021.png"/></svg:svg> recycling in determining the concentrations.