大气中总活性氯物种新检测方法及应用研究

Atmospheric active chlorines have been confirmed as one important source for atom radical Cl in the troposphere, and plays pivotal roles for removing atmospheric pollutants and producing of secondary pollutants. Although several technologies have been used to research the atmospheric active chlorines, all the environmental processes of the active chlorines are hard to be understood well due to the limited observed data and species for the active chlorines. The existing monitor technologies still have some problems. The air pollution of O3 produced from photochemical reactions is very severe in the Northern China region. The recent observation results indicate that the produced Cl atoms enhanced the daily concentration of the O3 production rate by 19%. According to the theory principle that the atom Cl easily produced from the photolysis of active chlorines can quickly abstract a hydrogen from alkanes to form HCl, a new detcetion method will be developed to observe all the species of active chlorines in the atmosphere. The method is a system including photoactive conversion section (PC), stripping coil capture section (SC) and ion chromatography detector section (IC). The total concentrations of atmospheric active chlorines can be detected sensitively. Basing on the monitor system, the concentration and variation characteristics of the whole active chlorines in the typical areas of the Northern China region will be studied. These results could be helpful to evaluate the influence of the active chlorines on regional atmospheric oxidants formation from photochemical processes.

大气中活性氯物种是对流层大气Cl原子的重要来源，在大气污染物去除以及二次污染物形成方面发挥着至关重要作用。尽管人们已利用多种监测技术开展大气中活性氯物种的研究，但有限的观测数据和观测物种不足以全面深入认识活性氯物种的大气环境行为，且现有监测技术仍存在诸多不足。我国华北地区夏秋季光化学臭氧污染严重，该地区最新的有限观测结果表明大气中活性氯物种对该地区大气臭氧生成的贡献可高达19%。申请者基于大气中活性氯物种极易光解产生Cl原子，且Cl原子可与烷烃发生快速摘氢反应生成HCl的原理，拟研发一套新的检测方法——光解转化（PC）-螺旋管吸收（SC）-色谱检测（IC）系统，可实现大气中总活性氯物种的高灵敏可靠检测；拟采用所研发的检测系统，在华北典型地区开展大气中总活性氯物种的观测研究，获得研究地区大气中总活性氯物种的浓度水平及变化特征，为评估其对大气光化学氧化剂形成的影响提供重要科学依据。

大气中活性氯物种是对流层大气Cl原子的重要来源，在大气污染物去除以及二次污染物形成方面发挥着至关重要作用，且目前相关研究仍相对缺乏。本研究通过光化学转化以及湿法吸收和离子色谱检测，建立了大气中活性氯高灵敏可靠检测方法，并在华北农村地区开展外场观测，发现该地区大气中活性氯当量浓度为0~7.5ppb，平均值为1.9ppb。本研究发现了小麦秸秆老化过程中存在明显的醛酮类化合物排放，成功建立了主要醛酮类化合物的老化排放参数化方程，估算其排放对区域大气中白天OH自由基、HO2自由基、O3水平分别增加了0.4%、19.9%和12.3%。本研究通过系统外场观测发现华北农村地区大气臭氧生成的敏感化学处于VOCs控制区以及VOCs和NOx共同控制区，并探究大气VOCs的主要来源。该项目的实施对揭示华北地区大气污染成因提供了重要的科技支撑，对区域空气质量改善具有重要科学以及现实意义。