HFC-134a的大气转化过程模拟研究

HFC-134a is the most abundant HFC in the atmosphere, which is still increasing fast. Affected by many physical and chemical factors, the atmospheric transformation process of HFC-134a obviously shows the regional-distributed characters. Its main degradation product trifluoroacetic acid(TFA) finally accumulates in the aquatic environment and will harm the aquatic ecosystem. HFC-134a is mainly used as the refrigerant of automotive air-conditioner in China. Its consumption and emission are increasing annually, and its atmospheric concentration has obviously exceeded the global background level. However, the research on its atmospheric transformation process has not been reported. In the research, the emission inventory with the spatiotemporal characters will be built, and the related parameters of transformation mechanism will be summed . Besides, the field observations for the atmospheric HFC-134a and TFA concentration will be simultaneously conducted in four Chinese cities. On these bases, the atmospheric transformation process of HFC-134a will be simulated and the modeling results will be evaluated by the observation data. Finally, the model process analysis and sensitivity analysis will be adopted to find the main atmospheric transformation pathways and their key influencing factors. The research results will provide technologic support for evaluating the HFC-134a ecoenvironmental effects and formulating the sound control strategy.

HFC-134a是目前全球大气浓度最高、年增长速率最快的HFCs类温室气体，其大气降解过程受温度、云量等多种物化因素影响而具有明显的区域性特征，主要降解产物三氟乙酸（TFA）最终积累在水体环境中，将会对水生生态系统造成影响。在我国，HFC-134a主要被用作汽车空调的制冷剂，其消费量和排放量逐年增加，大气浓度已显著高于全球本底水平，但其针对其大气转化过程的研究仍未见报道。本研究将从HFC-134a的源排放入手，建立具有时间特征的网格化排放清单；从大气转化的微观层面，归纳化学机理及其相关参数；对我国HFC-134a的大气转化过程进行长期模拟,并采用多个典型城市同步开展的HFC-134a和TFA的外场观测数据，对模拟结果进行验证。最后采用模式过程分析技术和敏感性分析技术，识别主要大气转化途径及其关键影响因素，为评估我国HFC-134a的生态环境影响，制定相应的温室气体应对策略提供科学依据。

作为浓度水平最高、增长速率最快的HFCs 类物质，HFC-134a 的大气排放、浓度水平变化和大气转化过程日益得到国际社会的广泛关注。本研究围绕“HFC-134a的大气转化过程”这一科学问题，采用清单编制方法学、外场观测以及数值模拟技术，研究HFC-134a的大气转化过程，在HFC-134的时空排放特征、大气化学转化机理及其降解产物的演变趋势等方面取得了重要进展。主要成果包括：编制了1995-2030年中国县级尺度汽车空调消费制冷剂HFC-134a的排放清单，揭示了我国HFC-134a的源排放特征；建立了HFC-134a及其降解产物TFA的大气样品采集、预处理和检测方法，持续监测了北京、广州、杭州和兰州四个典型城市大气中HFC-134a的浓度变化，分析揭示了其排放特征与时空分布规律；确定了HFC-134a大气化学转化过程涉及的化学机理及其相关参数，识别其主要降解途径；通过模拟HFC-134a的大气转化过程，量化了HFC-134a降解对环境中TFA的贡献比例；通过开展其降解产物TFA的大气及重点水体浓度监测，分析了北京地区TFA大气及水体浓度的时间变化规律及影响因素，模拟TFA在水环境中的分布，为评估TFA的水生生态风险提供了基本信息。本项目的研究成果不仅准确描述了HFC-134a的大气转化过程，而且能够为评估HFC-134a及其降解产物的生态环境影响提供技术支持，为我国制定相应的气候变化应对策略提供科学依据。项目实施期间，课题组发表论文7篇（均为SCI收录）；受邀做国际会议报告5次。培养博士毕业生4名，硕士生1名。此外，参与成员获得自然科学基金——国际合作与交流项目资助1项。