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DOI	10.5194/acp-19-9641-2019
	Seasonal differences in formation processes of oxidized organic aerosol near Houston; TX
	Dai Q.; Schulze B.C.; Bi X.; Bui A.A.T.; Guo F.; Wallace H.W.; Sanchez N.P.; Flynn J.H.; Lefer B.L.; Feng Y.; Griffin R.J.
发表日期	2019
ISSN	16807316
起始页码	9641
结束页码	9661
卷号	19 期号:14
英文摘要	Submicron aerosol was measured to the southwest of Houston, Texas, during winter and summer 2014 to investigate its seasonal variability. Data from a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) indicated that organic aerosol (OA) was the largest component of nonrefractory submicron particulate matter (NR-PM1) (on average, 38%±13% and 47%±18% of the NR-PM1 mass loading in winter and summer, respectively). Positive matrix factorization (PMF) analysis of the OA mass spectra demonstrated that two classes of oxygenated OA (less- A nd more-oxidized OOA, LO and MO) together dominated OA mass in summer (77%) and accounted for 39% of OA mass in winter. The fraction of LO-OOA (out of total OOA) is higher in summer (70%) than in winter (44%). Secondary aerosols (sulfate+nitrate+ammonium+OOA) accounted for ∼76% and 88% of NR-PM1 mass in winter and summer, respectively, indicating NR-PM1 mass was driven mostly by secondary aerosol formation regardless of the season. The mass loadings and diurnal patterns of these secondary aerosols show a clear winter-summer contrast. Organic nitrate (ON) concentrations were estimated using the NO+x ratio method, with contributions of 31%-66% and 9%-17% to OA during winter and summer, respectively. The estimated ON in summer strongly correlated with LO-OOA (r=0.73) and was enhanced at nighttime. The relative importance of aqueous-phase chemistry and photochemistry in processing OOA was investigated by examining the relationship of aerosol liquid water content (LWC) and the sum of ozone (O3) and nitrogen dioxide (NO2) (Ox=O3+NO2) with LO-OOA and MO-OOA. The processing mechanism of LO-OOA apparently was related to relative humidity (RH). In periods of RH<80%, aqueous-phase chemistry likely played an important role in the formation of wintertime LO-OOA, whereas photochemistry promoted the formation of summertime LO-OOA. For periods of high RH>80%, these effects were opposite those of low-RH periods. Both photochemistry and aqueous-phase processing appear to facilitate increases in MO-OOA concentration except during periods of high LWC, which is likely a result of wet removal during periods of light rain or a negative impact on its formation rate.The nighttime increases in MO-OOA during winter and summer were 0.013 and 0.01μg MO-OOA per μg of LWC, respectively. The increase in LO-OOA was larger than that for MO-OOA, with increase rates of 0.033 and 0.055μg LO-OOA per μg of LWC at night during winter and summer, respectively. On average, the mass concentration of LO-OOA in summer was elevated by nearly 1.2μgm-3 for a ∼20μg change in LWC, which was accompanied by a 40ppb change in Ox. © 2019 Author(s).
语种	英语
scopus关键词	aerosol; mass spectrometry; matrix; particulate matter; seasonal variation; summer; winter; Houston; Texas; United States
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/144245
作者单位	State Environ. Protect. Key Lab. of Urban Ambient Air Particulate Matter Poll. Prev. and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China; Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, United States; Department of Earth and Atmospheric Sciences, University of Houston, Houston, TX 77004, United States; Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, United States; Department of Environmental Science and Engineering, California Institute of Technology, Pasadena, CA 91125, United States; Washington State Department of Ecology, Lacey, WA 98503, United States; Division of Tropospheric Composition, NASA, Washington, DC 20024, United States
推荐引用方式 GB/T 7714	Dai Q.,Schulze B.C.,Bi X.,et al. Seasonal differences in formation processes of oxidized organic aerosol near Houston; TX[J],2019,19(14).
APA	Dai Q..,Schulze B.C..,Bi X..,Bui A.A.T..,Guo F..,...&Griffin R.J..(2019).Seasonal differences in formation processes of oxidized organic aerosol near Houston; TX.Atmospheric Chemistry and Physics,19(14).
MLA	Dai Q.,et al."Seasonal differences in formation processes of oxidized organic aerosol near Houston; TX".Atmospheric Chemistry and Physics 19.14(2019).