气候变化领域集成服务门户(CCPortal): Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study

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DOI	10.5194/acp-20-6671-2020
	Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study
	Rosanka S.; Vu G.H.T.; Nguyen H.M.T.; Pham T.V.; Javed U.; Taraborrelli D.; Vereecken L.
发表日期	2020
ISSN	1680-7316
起始页码	6671
结束页码	6686
卷号	20 期号:11
英文摘要	Isocyanic acid (HNCO) is a chemical constituent suspected to be harmful to humans if ambient concentrations exceed ∼1ppbv. HNCO is mainly emitted by combustion processes but is also inadvertently released by NOx mitigation measures in flue gas treatments. With increasing biomass burning and more widespread usage of catalytic converters in car engines, good prediction of HNCO atmospheric levels with global models is desirable. Little is known directly about the chemical loss processes of HNCO, which limits the implementation in global Earth system models. This study aims to close this knowledge gap by combining a theoretical kinetic study on the major oxidants reacting with HNCO with a global modelling study. The potential energy surfaces of the reactions of HNCO with OH and NO3 radicals, Cl atoms, and ozone were studied using high-level CCSD(T)/CBS(DTQ)//M06-2X/aug-cc-pVTZ quantum chemical methodologies, followed by transition state theory (TST) theoretical kinetic predictions of the rate coefficients at temperatures of 200-3000K. It was found that the reactions are all slow in atmospheric conditions, with k (300K) ≤ 7×10-16 cm3 molecule-1 s-1, and that product formation occurs predominantly by H abstraction; the predictions are in good agreement with earlier experimental work, where available. The reverse reactions of NCO radicals with H2O, HNO3, and HCl, of importance mostly in combustion, were also examined briefly. The findings are implemented into the atmospheric model EMAC (ECHAM/MESSy Atmospheric Chemistry) to estimate the importance of each chemical loss process on a global scale. The EMAC predictions confirm that the gasphase chemical loss of HNCO is a negligible process, contributing less than 1% and leaving heterogeneous losses as the major sinks. The removal of HNCO by clouds and precipitation contributes about 10%of the total loss, while globally dry deposition is the main sink, accounting for ∼ 90 %. The global simulation also shows that due to its long chemical lifetime in the free troposphere, HNCO can be efficiently transported into the UTLS by deep convection events. Dailyaverage mixing ratios of ground-level HNCO are found to regularly exceed 1 ppbv in regions dominated by biomass burning events, but rarely exceed levels above 10 ppt in other areas of the troposphere, though locally instantaneous toxic levels are expected. © 2020 Copernicus GmbH. All rights reserved.
语种	英语
scopus关键词	atmospheric chemistry; atmospheric modeling; biomass burning; concentration (composition); inorganic acid; nitrogen oxides; oxidant; reaction kinetics
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/141291
作者单位	Institute for energy and climate research, Forschungszentrum Jülich GmbH, Jülich, Germany; Faculty of Chemistry, Center for Computational Science, Hanoi National University of Education, Hanoi, Viet Nam; School of Chemical Engineering, Hanoi University of Science and Technology, Hanoi, Viet Nam
推荐引用方式 GB/T 7714	Rosanka S.,Vu G.H.T.,Nguyen H.M.T.,et al. Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study[J],2020,20(11).
APA	Rosanka S..,Vu G.H.T..,Nguyen H.M.T..,Pham T.V..,Javed U..,...&Vereecken L..(2020).Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study.Atmospheric Chemistry and Physics,20(11).
MLA	Rosanka S.,et al."Atmospheric chemical loss processes of isocyanic acid (HNCO): a combined theoretical kinetic and global modelling study".Atmospheric Chemistry and Physics 20.11(2020).