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DOI	10.5194/acp-21-129-2021
	The production and hydrolysis of organic nitrates from OH radical oxidation of β-ocimene
	Morales A.C.; Jayarathne T.; Slade J.H.; Laskin A.; Shepson P.B.
发表日期	2021
ISSN	1680-7316
起始页码	129
结束页码	145
卷号	21 期号:1
英文摘要	Biogenic volatile organic compounds (BVOCs) emitted by plants represent the largest source of non-methane hydrocarbon emissions on Earth. Photochemical oxidation of BVOCs represents a significant pathway in the production of secondary organic aerosol (SOA), affecting Earth's radiative balance. Organic nitrates (RONO2), formed from the oxidation of BVOCs in the presence of NOx, represent important aerosol precursors and affect the oxidative capacity of the atmosphere, in part by sequestering NOx. In the aerosol phase, RONO2 hydrolyze to form nitric acid and numerous water-soluble products, thus contributing to an increase in aerosol mass. However, only a small number of studies have investigated the production of RONO2 from OH oxidation of terpenes, and among those, few have studied their hydrolysis. Here, we report a laboratory study of OH-initiated oxidation of β-ocimene, an acyclic, tri-olefinic monoterpene released during the daytime from vegetation, including forests, agricultural landscapes, and grasslands. We conducted studies of the OH oxidation of β-ocimene in the presence of NOx using a 5.5 m3 all-Teflon photochemical reaction chamber, during which we quantified the total (gas-and particle-phase) RONO2 yield and the SOA yields. We sampled the organic nitrates produced and measured their hydrolysis rate constants across a range of atmospherically relevant pH. The total organic nitrate yield was determined to be 38(±9) %, consistent with the available literature regarding the dependence of organic nitrate production (from RO2 C NO) on carbon number. We found the hydrolysis rate constants to be highly pH dependent, with a hydrolysis lifetime of 51(±13) min at pH D 4 and 24(±3) min at pH D 2.5, a typical pH for deliquesced aerosols. We also employed highresolution mass spectrometry for preliminary product identification. The results indicate that the ocimene SOA yield (< 1 %) under relevant aerosol mass loadings in the atmosphere is significantly lower than reported yields from cyclic terpenes, such as a-pinene, likely due to alkoxy radical decomposition and formation of smaller, higher-volatility products. This is also consistent with the observed lower particlephase organic nitrate yields of β-ocimene-i.e., 1.5(±0.5) %-under dry conditions. We observed the expected hydroxy nitrates by chemical ionization mass spectrometry (CIMS) and some secondary production of the dihydroxy dinitrates, likely produced by oxidation of the first-generation hydroxy nitrates. Lower RONO2 yields were observed under high relative humidity (RH) conditions, indicating the importance of aerosol-phase RONO2 hydrolysis under ambient RH. This study provides insight into the formation and fate of organic nitrates, β-ocimene SOA yields, and NOx cycling in forested environments from daytime monoterpenes not currently included in atmospheric models. © 2021 Author(s).
语种	英语
scopus关键词	aerosol composition; aerosol formation; decomposition analysis; hydrolysis; nitrate; oxidation; pH; volatile organic compound
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/247243
作者单位	Department of Chemistry, Purdue University, West Lafayette, IN 47906, United States; Department of Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093, United States; Department of Earth Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47906, United States; School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, United States; Bristol Myers Squibb, 1 Squibb Drive, New Brunswick, NJ 08901, United States
推荐引用方式 GB/T 7714	Morales A.C.,Jayarathne T.,Slade J.H.,et al. The production and hydrolysis of organic nitrates from OH radical oxidation of β-ocimene[J],2021,21(1).
APA	Morales A.C.,Jayarathne T.,Slade J.H.,Laskin A.,&Shepson P.B..(2021).The production and hydrolysis of organic nitrates from OH radical oxidation of β-ocimene.ATMOSPHERIC CHEMISTRY AND PHYSICS,21(1).
MLA	Morales A.C.,et al."The production and hydrolysis of organic nitrates from OH radical oxidation of β-ocimene".ATMOSPHERIC CHEMISTRY AND PHYSICS 21.1(2021).