京津冀城市群大气霾污染形成机制及调控原理研究

In recent 30 years, economy of the Beijing-Tianjin-Hebei urban agglomeration has been developing rapidly. However, the atmospheric haze pollution has also been more and more serious. The frequency, intensity and area of haze days increases, but the physical and chemical formation mechanism are not clear, so the regional combined control is lack of scientific basis. In this application plan, various real time high technology monitoring devices and delicate sample analyzing methods are used in order to reveal the relationship of regional haze formation with mass and number concentration of atmospheric fine particle and chemical composition and concentration of particles with different size; analyze the variation of essential meteorological elements in haze weather process and typical change characteristics of regional atmospheric boundary structure, and then research the direct and indirect effects of micro physical process and chemical changes of atmospheric fine particle and its precursor on the formation of regional haze, especially the special effect of the regional emitted gaseous precursors and secondary aerosols on regional haze forming process of urban agglomeration. A statistical forecasting model is set up which include many factors related to the formation of haze such as physical properties and chemical composition of fine particle, meteorological element, weather process, atmospheric boundary structure and so on, combined with the air quality numerical model, so as to imitate and evaluate respective contributions of pollutants and emission quantities of different district on the regional haze forming process, checking and subjoining the existing pollutants emission inventory, providing scientific bases for the combined control of haze pollution from the source in Beijing-Tianjin-Hebei region.

近年30来，京津冀城市群经济发展迅速，但大气霾污染同时凸显。霾天频次增加、强度加大、区域变广，但其形成的物理、化学机制仍然不清，区域联防联控缺乏科学基础。本申请计划使用多种实时高技术监测手段和精密样品分析方法，揭示区域霾形成与大气细粒子质量浓度、数浓度和不同粒径段粒子的化学物种及浓度之间的关系；分析霾天气过程关键气象要素的变化和区域大气边界层结构的典型变化特征，进而研究大气细粒子及其前体物的微物理过程和化学变化对区域宏观霾形成的直接或是间接作用，特别是区域排放的气态前体物和二次气溶胶对城市群区域霾天气过程形成的独特影响。建立霾形成与细粒子物理特性、化学成分谱、气象要素、天气过程和大气边界层结构等多因子统计预测模型，并结合空气质量数值模式，模拟、评估区域内不同地区污染排放物种和排放量对区域霾形成的各自贡献，校核、增补现有污染源排放清单，为京津冀区域从源头协同防控大气霾污染提供科学依据。

随着经济的腾飞，城市化进程不断加速，高速发展的城市群交通和汽车产业又导致了严重的机动车排放污染，京津冀城市群污染已经演变成为以高浓度细粒子（全年）和高浓度臭氧污染（夏秋季节）为特征的“双高”型区域污染。对京津冀地区大气污染联合观测，深入分析区域雾霾形成机制及化学组成，对认知京津冀大气复合污染时空格局演变和相互输送过程具有重要科学意义，对我国其他城市群区域大气污染联合防控研究也具有重要的借鉴意义。因此，开展区域雾霾形成机制研究具有重要的科学意义和迫切的现实需求。.本项目针对京津冀环区域集成地面站点联网、高塔对致霾粒子的质量浓度、数浓度、化学成分、光学特性以及同期的致霾粒子前体物浓度、气象条件和大气边界层结构等参数的观测，获得区域重度污染时空演变特征及其形成的物理化学机制；阐述京津冀区域霾污染形成机制的季节差异，区分不同地区污染源排放对整个区域霾污染形成的各自贡献率；为制定京津冀区域霾污染协同防控措施提供科学基础和依据。.通过京津冀观测，发现大气中NOx的大量存在能够极大地促进SO2向硫酸盐的转化，并结合实验室烟雾箱模拟，首次明确提出“氮氧化物中心说”的理论模型。利用多台雷达组网实时监测京津冀区域大气混合层高度，结合颗粒物化学成分在线解析技术，揭示了区域大气重霾污染成因。北京地区大气污染形成初期主要受偏南区域输送，而当污染形成局地污染源（如机动车）的排放则难以扩散，使得混合层内污染持续加强。北京重霾污染形成于周边以燃煤工业排放为主的污染物输送，而加强于本地以机动车排放为主的污染物叠加。 .根据此项研究成果，已对环保部门提出建议，在重霾污染过程来临的前2-3天提前预警，对区域固定源、特别是高架源进行提前消减和管控，一旦污染过程形成，要进一步限制本地污染源排放，才可能使污染峰值得到有效遏制。