Studies on chemistry and cycles of halogens in the troposphere

在这个项目中，我们进行了几个项目。包括(L)无机卤素及其大气行为的测量，(2)卤素测量的发展及其在大气中的应用，(3)卤化挥发性烃的大气行为，(4)气溶胶中的卤化有机物和有机气溶胶的分析，(5)非甲烷烃的碳同位素分析，(6)卤素在空气/水界面的动力学和相互作用，(7)生物卤化物的形成机理和循环。用这种方法观察到海盐颗粒形成卤素气体。我们还观察到海洋大气中Cl2浓度在白天下降，而HCl气体浓度在白天增加。研制了一台用于测量Br2和Cl2的化学电离质谱仪。利用该仪器进行了实验室实验，观察到了海盐颗粒表面因吸氯而形成的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。用吹扫捕集GC/MS分析了从太平洋采集的海水和空气样品中的全碳化合物。我们发现西北太平洋卤素化合物的季节变化在8/9月达到最大值。在海洋气溶胶中，我们首次鉴定出卤代有机酸和醛，包括溴琥珀酸和氯丁二酸。前者在靠近亚洲大陆的西北太平洋表现出较高的浓度，而后者在中太平洋表现出较高的浓度。基于对太平洋的观测，我们提出了新复盖的卤化有机化合物的光化学形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.