气候变化领域集成服务门户(CCPortal): Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities

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DOI	10.5194/acp-19-5959-2019
	Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities
	Li Y.; Shiraiwa M.
发表日期	2019
ISSN	16807316
起始页码	5959
结束页码	5971
卷号	19 期号:9
英文摘要	Secondary organic aerosols (SOA) account for a substantial fraction of air particulate matter, and SOA formation is often modeled assuming rapid establishment of gas-particle equilibrium. Here, we estimate the characteristic timescale for SOA to achieve gas-particle equilibrium under a wide range of temperatures and relative humidities using a state-of-the-art kinetic flux model. Equilibration timescales were calculated by varying particle phase state, size, mass loadings, and volatility of organic compounds in open and closed systems. Model simulations suggest that the equilibration timescale for semi-volatile compounds is on the order of seconds or minutes for most conditions in the planetary boundary layer, but it can be longer than 1 h if particles adopt glassy or amorphous solid states with high glass transition temperatures at low relative humidity. In the free troposphere with lower temperatures, it can be longer than hours or days, even at moderate or relatively high relative humidities due to kinetic limitations of bulk diffusion in highly viscous particles. The timescale of partitioning of low-volatile compounds into highly viscous particles is shorter compared to semi-volatile compounds in the closed system, as it is largely determined by condensation sink due to very slow re-evaporation with relatively quick establishment of local equilibrium between the gas phase and the near-surface bulk. The dependence of equilibration timescales on both volatility and bulk diffusivity provides critical insights into thermodynamic or kinetic treatments of SOA partitioning for accurate predictions of gas- and particle-phase concentrations of semi-volatile compounds in regional and global chemical transport models. © Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.
语种	英语
scopus关键词	aerosol; aerosol composition; concentration (composition); equilibrium; particulate matter; relative humidity; temperature gradient; timescale
来源期刊	Atmospheric Chemistry and Physics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/144436
作者单位	Department of Chemistry, University of California, Irvine, CA, United States
推荐引用方式 GB/T 7714	Li Y.,Shiraiwa M.. Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities[J],2019,19(9).
APA	Li Y.,&Shiraiwa M..(2019).Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities.Atmospheric Chemistry and Physics,19(9).
MLA	Li Y.,et al."Timescales of secondary organic aerosols to reach equilibrium at various temperatures and relative humidities".Atmospheric Chemistry and Physics 19.9(2019).