我国南方典型农作物秸秆燃烧烟气老化生成二次有机气溶胶的模拟和观测研究

The evolution of primary organic aerosol (POA) plays a key role in secondary organic aerosol (SOA) formation. Since biomass burning (BB) is the predominant POA source, it is important to accurately estimate the SOA contribution from BB evolution. However, due to the lack of simulation study focusing on the influence of environmental parameters on the aging process, there is limited knowledge in the aging mechanism and the chemical evolution during aging exhibites dissonance between chamber and the ambient. This study will focus on the smoke aging of straw burning which is the dominated BB type in China. The typical agriculture residues in South China will be selected to do the experiments. First, the organic aerosol enhancement ratio (OA-ER) and the chemical evolution trends during the aging preocess will be obtained based on the chamber simulation of different straws under different combustion conditions. Then, the influence of environmental parameters on smoke aging will be examined to discover the potiental mechanism of aging process on the basis of the simulation under single factor and multiple-factor combined conditions. Finally,field campaigns will be taken in the harvest seasons to check the similarity of chemical evolution (primary and secondary tracers) during smoke aging between chamber and the ambient as well as to estimate the SOA contribution from smoke aging in the real atmosphere. This study will provide information about the mechanism and parameterizations of smoke aging of straw burning.

一次气溶胶老化是二次有机气溶胶(SOA)生成的重要机制，生物质燃烧(BB)是全球最重要一次气溶胶排放源。准确估算BB烟气老化生成SOA的量对研究区域空气质量及全球气候变化有重要意义。然而，缺乏环境因素对老化过程影响的系统模拟，导致老化生成SOA机制不明，模拟获得的化学组成演化趋势与实际大气观测存在较大偏差。本研究以农作物秸秆这一我国突出BB形式为切入点，以我国南方典型农作物秸秆为研究对象，从烟雾箱模拟和野外观测两方面入手，首先获取不同秸秆，不同燃烧方式下烟气老化生成SOA的产率(OA-ER值)和化学组成演化趋势；再通过不同环境因素单一和复合影响下的模拟，明确这些环境因素影响老化过程的机制；最后通过野外观测，对比实际大气和模拟过程中与秸秆燃烧相关的一次和二次标志物演化趋势，并对秸秆烟气老化生成SOA的量进行估算。本研究的开展可为准确估算秸秆烟气老化对大气SOA贡献提供重要的机制和参数化基础。

生物质燃烧（BB）是全球最重要的有机气溶胶排放源，BB烟气老化会生成大量二次有机气溶胶（SOA），准确估算BB 烟气老化生成SOA 的量对研究区域空气质量及全球气候变化有重要意义。本项目以农作物秸秆这一我国突出BB 形式为切入点，从实验室模拟和野外观测两方面，系统研究BB对SOA的贡献。实验室模拟方面，项目实测了3种生物质秸秆，露天焚烧排放颗粒物9级粒径的75种化学组成，以及22种生物质露天焚烧排放萜烯类化合物（Terpenoids）的排放特征。运用烟雾箱，模拟了2种我国南方地区主要农作物秸秆烟气老化过程，测定了其生成SOA 的产率（OA-ER 值）；揭示高氮氧化物（NOx）浓度会减小OA-ER值，二氧化硫（SO2）存在会显著提升OA-ER值；发现BB老化过程中，有机气溶胶中代表一次排放的f60逐渐降低，而代表异戊二烯SOA的f53却显著升高，表明BB老化过程中有大量异戊二烯SOA生成；针对α-蒎烯和甲苯这2种BB排放的重要前体物，运用同位素标记技术研究了2种SOA的混合过程。野外观测方面，项目系统探讨了区域-国家-全球尺度下，BB对大气SOA的影响。我们估算了BB对珠三角水溶性有机碳（WSOC）的贡献超过40%，是珠三角秋冬季大气PM2.5中WSOC的最主要来源；发现BB过程会促进萜烯类SOA的生成，这是我国秋冬季萜烯类SOA的重要来源；揭示西伯利亚森林大火显著改变北太平洋和北极地区异戊二烯SOA组成。项目共发表标注论文9篇，其中SCI论文7篇，包括2篇J Geophys Res-Atmos、2篇Environ Sci Technol、1篇Atmos. Chem. Phys.、1篇Sci Rep和1篇Sci Total Environ，全部为ISI的JCR 分区的领域Q1刊物。获得广东省科学技术一等奖1次。相关结果为准确估算BB烟气老化对大气SOA 贡献提供了较重要的机制和参数化基础。