大气硝酸盐中氮氧稳定同位素研究进展

受人类活动和工农业快速发展的影响,大气硝酸盐(NO_3^-)污染越来越严重且已成为世界范围内的环境问题之一。探究大气NO_3^-的稳定同位素组成(δ15N,δ18O和Δ17O),可以为深入理解大气氮循环、有效控制大气NO_3^-污染提供有力依据。综述了目前大气NO_3^-不同来源NOx的δ15N值、NO_3^-的δ15N季节变化特征及主要影响因素,总结了大气中不同氧化剂的δ18O值和Δ17O值,归纳了全球范围内部分大气NO_3^-中δ18O值和Δ17O值的时空分布特征及可能影响因素,回顾了NO_3^-同位素分析测试技术的主要进展,在前期工作基础上提出未来大气NO_3^-稳定同位素研究应更多关注NO_3^-的氧化生成机制(不同类型氧化剂同位素组成时空差异)、不同NOx来源的δ15N组成、借助化学模型开展大气NO_3^-循环过程等方面的研究。

Review of the Study on the Stable Isotopes of Nitrogen and Oxygen in Atmospheric Nitrate

Due to the emissions from intensive human activities and rapid development of industry and agriculture,atmospheric nitrate(NO3^-) contamination is becoming more serious and now is a worldwide environmental problem. The isotopic compositions of NO3^-(δ^15 N,δ^18 O and Δ^17 O)can deliver more information than the concentration alone,i.e.,the nitrogen and oxygen isotopes can suggest the sources of NO3^- and oxidation capability of the atmosphere,providing a powerful tool for investigating atmospheric nitrogen cycling and atmospheric NO3^- pollution control. The δ^15 N of different sourced NO3^- in the atmosphere,as well as the seasonal variation of δ^15 N(NO3^-)and the associated mechanisms were reviewed. In addition,the oxygen isotopes of various oxidants and NO3^-(δ^18 O and Δ^17 O) in the atmosphere were summarized,and the global distribution patterns of the oxygen isotopes of NO3^- were discussed. Lastly,the available analysis techniques of isotopic compositions of NO3^- were reviewed. Based on the research progress of NO3^- isotopes in the atmosphere,it was suggested that further investigations should focus on measuring the isotopic compositions of oxidants and NOx from different sources,characterizing the production mechanisms of NO3^-,as well as investigating chemical recycling between NOx and NO3^- with the aid of atmospheric chemical models.