对流层活性卤素化学:充满机遇和挑战的研究领域

活性卤素物种(RHS)参与大气对流层中许多化学过程，影响许多重要物种的源和汇，在大气对流层化学中起着十分重要的作用，因此对流层活性卤素化学成为近年来国际大气化学研究的重要前沿研究领域。RHS在对流层的外场观测方法主要包括化学放大、大气压化学电离质谱（APCIMS）、长程差分吸收光谱（DOAS）、雾室和湿法化学分析法、光解法、碳同位素的比率法等。各种观测方法表明大气边界层中存在着不同种类的RHS，特别在海洋边界层、极地边界层和盐湖地区。RHS的浓度有较大的变化范围（10-12~10-10）。RHS可引起一些VOCs的氧化，影响HOx和NOx的反应，减少对流层O3，并对硫的氧化和汞化学有较大的影响。对流层RHS的源主要为有机卤素化合物的排放和海盐气溶胶的释放。在讨论RHS在对流层的循环转化的基础上，归纳总结出一个示意图；提出了现有的主要科学问题，进而展望了今后的研究前景。

REACTIVE HALOGEN CHEMISTRY IN THE TROPOSPHERE: A RESEARCH FIELD WITH MANY OPPORTUNITIES AND CHALLENGES

Reactive halogen species(RHS) is involved with many chemical processes in the atmospheric troposphere.It affects the sources and sinks of many important species in the atmosphere,and plays a significant role in the tropospheric chemistry.RHS chemistry in the troposphere is recently an important frontier research field in the international atmospheric chemistry research.The main field measure techniques of RHS in the troposphere include chemical amplification,atmospheric pressure ionization mass spectrometry(APIMS),differential optical absorption spectroscopy(DOAS),mist chamber and wet chemical detection,photolysable halogen detector(PHD) and the isotopic ratios.Various observation methods show that different kinds of RHS exist in the atmospheric boundary layer,particularly in the marine boundary layer,polar boundary layer,and over the regions of salt lake.RHS concentrations vary from 10~(-12) to 10~(-10).RHS can cause oxidation of some VOCs,influence the reaction of HOx and NOx,and make the loss of O_(3).RHS impacts on the oxidation of sulfur and on mercury chemistry.The source of RHS in the troposphere is mainly from the emission of organic halogen and from the release of sea-salt aerosols.The cycle and transformation of RHS in the troposphere are summarized.Main scientific problems are put forward,and research prospect is made.