Department of Meteorology and Atmospheric Science , Pennsylvania State University , University Park , Pennsylvania 16802 , United States.
Environ Sci Technol. 2019 Apr 2;53(7):3645-3652. doi: 10.1021/acs.est.8b06260. Epub 2019 Mar 15.
Secondary organic aerosol (SOA) particles, which are formed and aged in Earth's oxidizing atmosphere, influence climate and human health. Quantifying properties of SOA particles and oxidized organic compounds (OVOCs) requires controlled experiments in enclosures, but enclosures have walls that can alter the chemistry. Comparing wall effects for widely used large environmental chambers (ECs) and portable oxidative flow reactors (OFRs) is difficult. In this work, the Chamber Wall Index (CWI) is developed as the minimum ratio of the initial wall uptake time constant divided by the enclosure residence time. This index demonstrates that walls alter the chemistry less in OFRs than in ECs, due primarily to shorter residence times. Much shorter residence times may not be feasible because oxidation chemistry and microphysics need time to produce atmospherically relevant SOA and OVOCs. While all current OFRs have wall effects, it may be possible to develop a "wall-less" OFR.
次生有机气溶胶 (SOA) 粒子在地球的氧化气氛中形成和老化，影响气候和人类健康。定量测量 SOA 粒子和氧化有机化合物 (OVOC) 的特性需要在封闭室内进行控制实验，但封闭室的墙壁会改变化学性质。比较广泛使用的大型环境室 (EC) 和便携式氧化流动反应器 (OFR) 的墙壁效应比较困难。在这项工作中，开发了腔壁指数 (CWI)，作为初始壁吸收时间常数与封闭室停留时间之比的最小值。该指数表明，由于停留时间较短，壁对 OFR 中的化学变化的影响小于 EC。由于氧化化学和微物理学需要时间来产生与大气相关的 SOA 和 OVOC，因此较短的停留时间可能不可行。虽然所有当前的 OFR 都有壁效应，但开发“无壁”OFR 是可能的。
