Oxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaign
Oxygen isotope mass balance of atmospheric nitrate at Dome C, East Antarctica, during the OPALE campaign
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DOI：
10.5194/acp-16-2659-2016
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发表时间：
2015-09
影响因子：
6.3
通讯作者：
J. Savarino;W. Vicars;M. Legrand;S. Preunkert;B. Jourdain;M. Frey;A. Kukui;N. Caillon;J. G. Roca
中科院分区：
文献类型：
--
作者：
J. Savarino;W. Vicars;M. Legrand;S. Preunkert;B. Jourdain;M. Frey;A. Kukui;N. Caillon;J. G. Roca
抽象的。大气硝酸盐的稳定氧同位素组成的变化是研究对流层氧化过程的新工具。它们对决定大气氮氧化物（NO + NO2 = NOx）命运的途径提供了定性和定量的限制。臭氧中独特的17 O过量（Δ 17 O = δ 17 O − 0.52 × δ 18 O），通过氧化作用转化为NOx，是研究NOx转化过程中特别有用的同位素指纹。限制在氮氧化物循环的17 O过量的传播是至关重要的，在极地地区，那里存在的可能性，延长大气调查的冰川间冰期的时间尺度使用深冰芯记录的硝酸盐。在这里，我们提出了在Dome C（东南极高原）在2011年/2012年夏季收集的大气硝酸盐的综合同位素组成的测量。硝酸盐同位素分析首次与硝酸盐生产中涉及的关键前体（NOx，O3，OH，HO 2，RO 2等）相结合。以及直接观测到的地表臭氧的可转移Δ 17 O，这是在整个2012年使用我们最近开发的分析方法在Dome C测量的。假设硝酸盐主要是在夏季通过OH + NO2途径产生的，并利用OH和NO2的同时测量，我们计算出硝酸盐的Δ 17 O特征约为（21-22 ± 3）‰。这些值低于27至31 ‰之间的测量值。预期和观测到的Δ 17 O（NO3−）值之间的差异表明存在一个未知的过程，该过程对东南极地区的大气硝酸盐收支有重要贡献。然而，不能完全排除系统误差或错误的同位素平衡传递函数。
Abstract. Variations in the stable oxygen isotope composition of atmospheric nitrate act as novel tools for studying oxidative processes taking place in the troposphere. They provide both qualitative and quantitative constraints on the pathways determining the fate of atmospheric nitrogen oxides (NO + NO2 = NOx). The unique and distinctive 17O excess (Δ17O = δ17O − 0.52 × δ18O) of ozone, which is transferred to NOx via oxidation, is a particularly useful isotopic fingerprint in studies of NOx transformations. Constraining the propagation of 17O excess within the NOx cycle is critical in polar areas, where there exists the possibility of extending atmospheric investigations to the glacial–interglacial timescale using deep ice core records of nitrate. Here we present measurements of the comprehensive isotopic composition of atmospheric nitrate collected at Dome C (East Antarctic Plateau) during the austral summer of 2011/2012. Nitrate isotope analysis has been here combined for the first time with key precursors involved in nitrate production (NOx, O3, OH, HO2, RO2, etc.) and direct observations of the transferrable Δ17O of surface ozone, which was measured at Dome C throughout 2012 using our recently developed analytical approach. Assuming that nitrate is mainly produced in Antarctica in summer through the OH + NO2 pathway and using concurrent measurements of OH and NO2, we calculated a Δ17O signature for nitrate on the order of (21–22 ± 3) ‰. These values are lower than the measured values that ranged between 27 and 31 ‰. This discrepancy between expected and observed Δ17O(NO3−) values suggests the existence of an unknown process that contributes significantly to the atmospheric nitrate budget over this East Antarctic region. However, systematic errors or false isotopic balance transfer functions are not totally excluded.