气候变化领域集成服务门户(CCPortal): Non-equilibrium interplay between gas-particle partitioning and multiphase chemical reactions of semi-volatile compounds: Mechanistic insights and practical implications for atmospheric modeling ofpolycyclic aromatic hydrocarbons

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DOI	10.5194/acp-21-6175-2021
	Non-equilibrium interplay between gas-particle partitioning and multiphase chemical reactions of semi-volatile compounds: Mechanistic insights and practical implications for atmospheric modeling ofpolycyclic aromatic hydrocarbons
	Wilson J.; Pöschl U.; Shiraiwa M.; Berkemeier T.
发表日期	2021
ISSN	1680-7316
起始页码	6175
结束页码	6198
卷号	21 期号:8
英文摘要	Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic air pollutants. The dispersion of PAHs in the atmosphere is influenced by gas-particle partitioning and chemical loss. These processes are closely interlinked and may occur at vastly differing timescales, which complicates their mathematical description in chemical transport models. Here, we use a kinetic model that explicitly resolves mass transport and chemical reactions in the gas and particle phases to describe and explore the dynamic and nonequilibrium interplay of gas-particle partitioning and chemical losses of PAHs on soot particles. We define the equilibration timescale τeq of gas-particle partitioning as the e-folding time for relaxation of the system to the partitioning equilibrium. We find this metric to span from seconds to hours depending on temperature, particle surface area, and the type of PAH. The equilibration time can be approximated using a time-independent equation, τeq ≈ 1/kdesCkads , which depends on the desorption rate coefficient kdes and adsorption rate coefficient kads, both of which can be calculated from experimentally accessible parameters. The model reveals two regimes in which different physical processes control the equilibration timescale: a desorption-controlled and an adsorption-controlled regime. In a case study with the PAH pyrene, we illustrate how chemical loss can perturb the equilibrium particulate fraction at typical atmospheric concentrations of O3 and OH. For the surface reaction with O3, the perturbation is significant and increases with the gas-phase concentration of O3. Conversely, perturbations are smaller for reaction with the OH radical, which reacts with pyrene on both the surface of particles and in the gas phase. Global and regional chemical transport models typically approximate gas-particle partitioning with instantaneous-equilibration approaches.We highlight scenarios in which these approximations deviate from the explicitly coupled treatment of gas-particle partitioning and chemistry presented in this study.We find that the discrepancy between solutions depends on the operator-splitting time step and the choice of time step can help to minimize the discrepancy. The findings and techniques presented in this work not only are relevant for PAHs but can also be applied to other semivolatile substances that undergo chemical reactions and mass transport between the gas and particle phase. © Author(s) 2021.
语种	英语
scopus关键词	atmospheric chemistry; atmospheric gas; atmospheric modeling; chemical reaction; mass transport; PAH; partitioning; soot
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/246952
作者单位	Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz, Germany; Department of Chemistry, University of California, Irvine, CA, United States
推荐引用方式 GB/T 7714	Wilson J.,Pöschl U.,Shiraiwa M.,et al. Non-equilibrium interplay between gas-particle partitioning and multiphase chemical reactions of semi-volatile compounds: Mechanistic insights and practical implications for atmospheric modeling ofpolycyclic aromatic hydrocarbons[J],2021,21(8).
APA	Wilson J.,Pöschl U.,Shiraiwa M.,&Berkemeier T..(2021).Non-equilibrium interplay between gas-particle partitioning and multiphase chemical reactions of semi-volatile compounds: Mechanistic insights and practical implications for atmospheric modeling ofpolycyclic aromatic hydrocarbons.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(8).
MLA	Wilson J.,et al."Non-equilibrium interplay between gas-particle partitioning and multiphase chemical reactions of semi-volatile compounds: Mechanistic insights and practical implications for atmospheric modeling ofpolycyclic aromatic hydrocarbons".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.8(2021).