基于稀释和热扩散联用的民用生物质燃烧排放一次有机气溶胶的气固相分配特征研究

Organic aerosol, the main component of atmospheric fine particle, is underestimated by air quality modeling, which was mainly caused by underestimation of secondary organic aerosol (SOA) significantly. The newly developed three-dimensional air quality model incorporating with the two-dimensional volatility basis set (2D-VBS) box model has been proved to improve the simulation results of OA and SOA concentration significantly. 2D-VBS box model needs volatility distribution and oxygen-to-carbon ratio (O:C) of POA as input. Residential biofuel combustion, the most important contributor to organic carbon emissions in China. However, studies on volatility distribution and O:C ratio of POA from this source are limited. In view of this situation, we investigate the effects of POA concentration in the diluted gas and temperature on POA emissions from residential biofuel combustion in China using dilution and thermodenuder measurement. We will obtain O:C ratios of POA and its relationship with POA volatility, and infer key characteristic parameters of volatility distribution of POA emissions from residential biofuel combustion. We will also develop POA emission inventory from residential biofuel combustion in China based on 2D-VBS. Research results can be used for input parameters for air quality model and help to reduce the uncertainty of organic aerosol modeling.

有机气溶胶（OA）是大气PM2.5最重要的化学组分之一，空气质量模型对 OA浓度模拟低估，主要是模型对二次有机气溶胶（SOA）生成的显著低估造成。新近开发的二维挥发性区间模型（2D-VBS）耦合三维空气质量模拟系统可显著改善OA和SOA的模拟结果。2D-VBS模型需要源排放一次有机气溶胶（POA）挥发性及氧化态分布的信息作为输入参数。民用生物质燃烧是我国大气POA最主要的排放源，目前缺乏关于该源排放POA挥发性及氧化态分布的信息。针对这一现状，本课题拟通过基于稀释和热扩散法联用，研究我国典型民用生物质燃烧排放稀释后有机气溶胶的浓度和热扩散温度对一次有机气溶胶排放的影响，获得生物质排放一次有机气溶胶的氧化态分布及随挥发性的变化关系，提取出生物质燃烧排放一次有机气溶胶挥发性分布参数，建立基于挥发性/氧化态二维分布的我国民用生物质燃烧排放一次有机气溶胶排放清单，为模拟大气有机气溶胶提供科学支持。

有机气溶胶（OA）是大气PM2.5最重要的化学组分之一，空气质量模型对 OA浓度模拟低估，主要是模型对二次有机气溶胶（SOA）生成的显著低估造成。新近开发的二维挥发性区间模型（2D-VBS）耦合三维空气质量模拟系统可显著改善OA和SOA的模拟结果。2D-VBS模型需要源排放一次有机气溶胶（POA）挥发性及氧化态分布的信息作为输入参数。民用生物质燃烧是我国大气POA最主要的排放源，目前缺乏关于该源排放POA挥发性及氧化态分布的信息。针对这一现状，本课题通过基于稀释和热扩散法联用，研究了我国典型民用生物质燃烧排放稀释后有机气溶胶的浓度和热扩散温度对一次有机气溶胶排放的影响，发现将稀释比从20:1增加到120:1，生物质燃烧排放POA排放降低了75%-90%；受热后，POA中一部分挥发性物质会被蒸发，热扩散温度50C时质量剩余分数（MFR）数值为0.94±0.08；150C时MFR数值达到0.78±0.18；POA中O/C与OM/OC的比例会随热扩散温度的升高而逐渐增大；提取出生物质燃烧排放一次有机气溶胶挥发性分布参数，秸秆和木柴的logCi* 在(-2，-2，0，1，2，3，4)下的挥发性分布参数分别为(0.14, 0.09, 0.01, 0.07, 0.13, 0.18, 0.38)和(0.14, 0.08, 0.08, 0, 0.3, 0.1, 0.3)；并在此基础建立了基于挥发性的我国民用生物质燃烧排放一次有机气溶胶排放清单，研究结果可为模拟大气有机气溶胶提供科学支持。