Studies on chemistry and cycles of halogens in the troposphere

在这个项目中，我们做了几个项目。它们包括：（1）无机卤素的测量及其大气行为，（2）卤素测量的发展及其在大气中的应用，（3）卤代挥发性烃的大气行为，（4）气溶胶中卤代有机物及其分析，（5）非甲烷烃的碳同位素分析，（6）卤素在气/水界面中的动力学及其相互作用，（7）生物源卤烃的形成机理和循环。我们利用洗涤器技术建立了一个新的分析系统来测量卤烃气体。通过使用该方法，观察到从海盐颗粒形成卤素气体。我们还观察到白天海洋大气中Cl^2浓度的降低和HCl气体的增加。本文研制了一台用于测定Br^2和Cl^2的化学电离质谱仪。利用该仪器进行实验室实验，我们观察到由于Cl的吸收，在海盐颗粒表面形成了Br^2气体。我们还证实了通过与臭氧反应从海盐中释放出卤素气体。从太平洋收集的海水和空气样品进行了分析，使用吹扫和陷阱GC/质谱。我们发现，卤素化合物的季节变化与最大值在8月/9月在西北太平洋。在海洋气溶胶中，我们首次发现了卤代有机酸和醛，包括溴代琥珀酸和氯代琥珀酸。前者在北太平洋西部靠近亚洲大陆的海域浓度较高，而后者在中太平洋海域浓度升高。根据太平洋地区的观测资料，提出了新发现的卤代有机物的光化学生成模式和有机气溶胶的演化模式。

In this program, we conducted several projects. They include (l) measurements of inorganic halogens and their atmospheric behaviors, (2) development of halogen measurement and its application to the atmosphere, (3) atmospheric behaviors of halogenated volatile hydrocarbons, (4) halogenated organics in aerosols and analysis of organic aerosols, (5) carbon isotopic analysis of non-methane hydrocarbons, (6) dynamics and interaction of halogens in air/water interface, and (7) formation mechanism and cycles of biogenic halocarbons.We made a new analytical system to measure hologen gases by using scrubber technique. By using this method, a formation of halogen gases from the sea salt particles was observed. We also observed a decrease in the concentration of Cl^2 and an increase of HCl gas in daytime in the marine atmosphere. A chemical ionization mass spectrometer that was designed for the measurement of Br^2 and Cl^2, has been made in this study. Using this instrument for laboratory experiment, we observed the formation of Br^2 gas on the surface of sea salt particles as a result of Cl uptake. We also confirmed the release of halogen gases from the sea salts by the reaction with ozone. Seawater and air samples collected from the Pacific Ocean were analyzed for holocarbons using a purge and trap GC/mass spectrometry. We found a seasonal change of halogen compounds with maxima in August/September in the western North Pacific. In the marine aerosols, we identified, for the first time, halogenated organic acids and aldehydes, including bromosuccinic and chlorosuccinic acids. The former acid showed higher concentrations in the western North Pacific near Asia continent, whereas the latter increased in the central Pacific. Based on the observations over the Pacific, we proposed a photochemical formation model for the newly rescovered halogenated organic compounds and an evolution model of organic aerosols.