硝酰氯的大气化学

Atmospheric Chemistry of Nitryl Chloride

硝酰氯(nitryl chloride,ClNO2)是大气中一种重要的气态污染物,对大气氧化性、一次污染物的降解和二次污染物的生成具有重要影响,并在全球氮循环和氯循环中扮演着不可忽视的角色。本文归纳了ClNO2的基本物理化学性质及其在大气中的生成和去除机制,并介绍了实验室研究和外场观测中ClNO2的主要测量方法。在此基础上,本文总结了过去十几年报道的ClNO2在实际大气中的时空分布特征,通过分析实验室模拟和外场观测的研究结果系统讨论了ClNO2非均相生成的机制、产率及其影响因素,探讨了ClNO2对氯自由基、大气氧化性以及臭氧和硝酸盐形成的影响。我们指出,ClNO2既耦合了气相化学和非均相化学,又耦合了夜间大气化学和日间光化学,在我国大气复合污染中可能起着非常重要的作用。最后,本文提出了ClNO2大气化学研究中尚待解决的关键科学问题,并简要讨论了该领域的未来发展方向。

As an important reactive trace gases in the troposphere,nitryl chloride(ClNO2)has significant impacts on atmospheric oxidation capacity,the degradation of primary pollutants and the formation of secondary pollutants,and plays indispensable roles in global cycles of both nitrogen and chlorine.In this paper,we introduce basic properties of ClNO2 as well as its formation and removal mechanisms in the troposphere,and describe in brief techniques currently used in laboratory and field work to measure ClNO2.In addition,we review spatial and temporal distributions of tropospheric ClNO2 over the globe as reported in the last 10~20 years,discuss in a systematical manner chemical mechanisms and environmental factors which determine its heterogeneous formation in the atmosphere via critical analysis of important results from laboratory studies and field measurements,and summarize impacts of ClNO2 on chlorine radicals,atmospheric oxidation capacity as well as the formation of O3 and nitrate aerosol.We emphasize that ClNO2 couples gas phase chemistry and heterogeneous chemistry,and also couples nocturnal atmospheric chemistry with daytime photochemistry,thus very likely playing an important role in the formation of air pollution complex in China.Important questions which remain to be answered to better understand atmospheric chemistry of ClNO2 are outlined at the end,and we also discuss in brief how these questions can be addressed in future work.