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冰川冻土 ›› 2021, Vol. 43 ›› Issue (5): 1344-1353.doi: 10.7522/j.issn.1000-0240.2021.0088

• 冰冻圈与全球变化 • 上一篇    下一篇

氧同位素示踪夏季北冰洋(62.3°~74.7° N)大气硝酸盐形成途径的研究

贺鹏真1,2(),谢周清1,3()   

  1. 1.中国科学技术大学 极地环境与全球变化安徽省重点实验室,安徽 合肥 230026
    2.皖西学院 环境与旅游学院,安徽 六安 237012
    3.中国科学院 城市环境研究所,福建 厦门 361021
  • 收稿日期:2021-07-08 修回日期:2021-10-04 出版日期:2021-10-31 发布日期:2021-12-09
  • 通讯作者: 谢周清 E-mail:hpz@mail.ustc.edu.cn;zqxie@ustc.edu.cn
  • 作者简介:贺鹏真,讲师,主要从事气溶胶大气化学研究. E-mail: hpz@mail.ustc.edu.cn
  • 基金资助:
    国家自然科学基金项目(41941014);自然资源部项目(IRASCC2020-2022-01-01-01);安徽省自然科学基金青年项目(2008085QD184);皖西学院高层次人才科研启动资金项目(WGKQ202001007)

Using oxygen isotopes to trace the formation pathways of atmospheric nitrate over summer Arctic Ocean (62.3°~74.7° N)

Pengzhen HE1,2(),Zhouqing XIE1,3()   

  1. 1.Anhui Province Key Laboratory of Polar Environment and Global Change,University of Science and Technology of China,Hefei 230026,China
    2.School of Environment and Tourism,West Anhui University,Lu’an 237012,Anhui,China
    3.Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361021,Fujian,China
  • Received:2021-07-08 Revised:2021-10-04 Online:2021-10-31 Published:2021-12-09
  • Contact: Zhouqing XIE E-mail:hpz@mail.ustc.edu.cn;zqxie@ustc.edu.cn

摘要:

大气硝酸盐(包括颗粒态硝酸盐和气态硝酸)是一种重要的含氮物质,在北冰洋氮的生物地球化学循环中起着重要作用。然而,目前关于北冰洋上大气硝酸盐形成机制的研究较少,限制了对该地区氮氧化物(NOX)到硝酸盐相关大气化学过程的理解。作为2012年夏季中国第五次北极科学考察的内容之一,本研究采集了科考航线上的大气气溶胶样品,并对北冰洋航段(62.3°~74.7° N)上样品中硝酸盐的氮氧同位素(δ15N,δ17O和δ18O)进行了分析以研究该区域大气硝酸盐的形成过程。观测到的Δ17O(NO3)变化范围为21.7‰~28.8‰,均值为(25.4±2.7)‰;δ15N(NO3)变化范为是-7.5‰~0.8‰,均值为(-4.2±3.0)‰。整体上,Δ17O(NO3)与采样纬度呈现相反的变化趋势,与夜间时长和O3浓度呈现相似的变化趋势;δ15N(NO3)与气温呈现相反的变化趋势。基于化学动力学的分析表明,Δ17O(NO3)的变化可能主要反映的是NO2+OH、N2O5+H2O(aq)、NO3+HC/DMS、NO3+H2O(aq)、XNO3+H2O(aq)(X=Br、Cl、I)等硝酸盐生成途径的变化。基于Δ17O(NO3)的计算表明:低Δ17O(NO3)样品[Δ17O(NO3)=21.7‰~24.5‰,66.2°~74.7° N]的主导反应为NO2+OH,其对硝酸盐的可能平均贡献是68%~81%;对于高Δ17O(NO3)样品[Δ17O(NO3)=27.5‰~28.8‰,62.3°~69.9° N],NO3+HC/DMS、NO3+H2O(aq)和XNO3+H2O(aq)三者一起的贡献最高,可达35%~50%。结合BrO柱浓度的分析表明,XNO3+H2O(aq)反应对高Δ17O(NO3)样品的作用可能不可忽略,该作用有待结合大气化学模型进一步探索。

关键词: 北极, 气溶胶, 硝酸盐, 形成途径, 氧同位素

Abstract:

Atmospheric nitrate (particulate nitrate + gaseous HNO3) plays an essential role in the biogeochemical cycle of nitrogen in the Arctic region. However, there are poor studies on the formation mechanisms of atmospheric nitrate over the Arctic Ocean, which limits our understanding of atmospheric chemical processes related to nitrogen oxides (NOX=NO+NO2) and nitrate in this area. As part of 5th Chinese National Arctic Research Expedition (CHINARE) in the summer of 2012, aerosol filter samples were collected and nitrogen and oxygen isotopes of nitrate (δ15N, δ17O and δ18O) in the filter samples in 62.3°~74.7° N were analyzed to trace the formation pathways of atmospheric nitrate over the Arctic Ocean. The observed daily Δ17O(NO3) (=δ17O–0.52δ18O) varied from 21.7‰ to 28.8‰ with the mean of (25.4±2.7)‰ and δ15N(NO3) ranged from -7.5‰ to 0.8‰ with the mean of (-4.2±3.0)‰. Generally speaking, Δ17O(NO3) showed a opposite trend with the sampling latitude, and a similar trend with the nighttime hours and O3 concentration. While δ15N(NO3) showed the opposite trend with air temperature. Chemical kinetics calculations show that the variation of Δ17O(NO3) may be mainly determined by the role of different pathways in nitrate production rather than the relative importance of O3 and XO (X=Br, Cl and I) in NOX cycling, the latter was estimated to be 0.81~0.90 with the mean of 0.85±0.03. Further analysis based on Δ17O(NO3) showed that NO2+OH pathway dominated nitrate production for samples with low Δ17O(NO3) (=21.7‰~24.5‰, 66.2°~74.7° N), with the mean possible contribution of 68%~81%. For samples with relatively high Δ17O(NO3) (=27.5‰~28.8‰, 62.3°~69.9° N), the together role of NO3+HC/DMS, NO3+H2O(aq) and XNO3+H2O(aq) are the most important, with the mean possible contribution of 35%~50%. Combined with the analysis of BrO column concentrations, it was found that the role of XNO3+H2O(aq) in nitrate production cannot be ignored for high Δ17O(NO3) samples (e.g., Δ17O=28.8‰), the role of which needs to be further explored with the combination of atmospheric chemistry model in future studies.

Key words: Arctic, aerosol, nitrate, formation mechanisms, oxygen isotopes

中图分类号: 

  • O648.18