State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China; Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, Nanjing University of Information Science and Technology, Nanjing 210044, China.
Sci Total Environ. 2021 Oct 20;792:148035. doi: 10.1016/j.scitotenv.2021.148035. Epub 2021 Jun 1.
The phase state of biomass burning aerosols (BBA) remains largely unclear, impeding our understanding of their effects on air quality, climate and human health, due to its profound roles in mass transfer between gaseous and particulate phase. In this study, the phase state of BBA was investigated by measuring the particle rebound fraction ƒ combining field observations and laboratory experiments. We found that both ambient and laboratory-generated BBA had unexpectedly lower rebound fraction ƒ (<0.6) under the dry conditions (RH = 20-50%), indicating that BBA were in non-solid state at such low RH. This was obviously different from the secondary organic aerosols (SOA) derived from the oxidation of both anthropogenic and biogenic volatile organic compounds, typically with a rebound fraction ƒ larger than 0.8 at RH below 50%. Therefore, we proposed that the diffusion coefficient of gaseous molecular in the bulk of BBA might be much higher than SOA under the dry conditions.
生物质燃烧气溶胶（BBA）的相态在很大程度上仍不清楚，由于其在气相和颗粒相之间的物质传递中起着重要作用，这阻碍了我们对其对空气质量、气候和人类健康的影响的理解。在这项研究中，通过测量颗粒回弹分数 ƒ，结合现场观测和实验室实验，研究了 BBA 的相态。我们发现，在干燥条件下（相对湿度为 20-50%），环境和实验室产生的 BBA 的回弹分数 ƒ 出乎意料地低（<0.6），这表明在如此低的相对湿度下，BBA 处于非固态。这与源自人为和生物挥发性有机化合物氧化的二次有机气溶胶（SOA）明显不同，通常在相对湿度低于 50%时，SOA 的回弹分数 ƒ 大于 0.8。因此，我们提出，在干燥条件下，BBA 中气态分子的扩散系数可能远高于 SOA。
