气候变化领域集成服务门户(CCPortal): Effects of water-soluble organic carbon on aerosol pH

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DOI	10.5194/acp-19-14607-2019
	Effects of water-soluble organic carbon on aerosol pH
	Battaglia M.A.; Weber R.J.; Nenes A.; Hennigan C.J.
发表日期	2019
ISSN	16807316
起始页码	14607
结束页码	14620
卷号	19 期号:23
英文摘要	Water-soluble organic carbon (WSOC) is a ubiquitous and significant fraction of fine particulate matter. Despite advances in aerosol thermodynamic equilibrium models, there is limited understanding on the comprehensive impacts of WSOC on aerosol acidity (pH). We address this limitation by studying submicron aerosols that represent the two extremes in acidity levels found in the atmosphere: strongly acidic aerosol from Baltimore, MD, and weakly acidic conditions characteristic of Beijing, China. These cases are then used to construct mixed inorganic-organic single-phase aqueous particles and thermodynamically analyzed by the Extended Aerosol Inorganics Model (E-AIM) and ISORROPIA models in combination with activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficient) to evaluate the effects of WSOC on the HC ion activity coefficients (?HC) and activity (pH). We find that addition of organic acids and nonacid organic species concurrently increases ?HC and aerosol liquid water. Under the highly acidic conditions typical of the eastern US (inorganic-only pH ~ 1), these effects mostly offset each other, giving pH changes of < 0.5 pH units even at organic aerosol dry mass fractions in excess of 60 %. Under conditions with weaker acidity typical of Beijing (inorganic-only pH ∼ 4:5), the nonacidic WSOC compounds had similarly minor effects on aerosol pH, but organic acids imparted the largest changes in pH compared to the inorganic-only simulations. Organic acids affect pH in the order of their pKa values (oxalic acid > malonic acid > glutaric acid). Although the inorganic-only pH was above the pKa value of all three organic acids investigated, pH changes in excess of 1 pH unit were only observed at unrealistic organic acid levels (aerosol organic acid concentrations > 35 μ g m-3) in Beijing. The model simulations were run at 70 %, 80 %, and 90 % relative humidity (RH) levels and the effect of WSOC was inversely related to RH. At 90 % RH, WSOC altered aerosol pH by up to ~ 0:2 pH units, though the effect was up to ~ 0:6 pH units at 70 % RH. The somewhat offsetting nature of these effects suggests that aerosol pH is sufficiently constrained by the inorganic constituents alone under conditions where liquid-liquid phase separation is not anticipated to occur. © 2019 Author(s).
语种	英语
scopus关键词	acidity; aerosol property; organic acid; organic carbon; pH; Beijing [China]; China
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/144000
作者单位	Department of Chemical Biochemical and Environmental Engineering, University of Maryland, Baltimore County, Baltimore, MD 21250, United States; School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, United States; Institute for Chemical Engineering Sciences, Foundation for Research and Technology - Hellas, Patras, 26504, Greece; Laboratory of Atmospheric Processes and Their Impacts, School of Architecture Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, Lausanne, 1015, Switzerland
推荐引用方式 GB/T 7714	Battaglia M.A.,Weber R.J.,Nenes A.,et al. Effects of water-soluble organic carbon on aerosol pH[J],2019,19(23).
APA	Battaglia M.A.,Weber R.J.,Nenes A.,&Hennigan C.J..(2019).Effects of water-soluble organic carbon on aerosol pH.Atmospheric Chemistry and Physics,19(23).
MLA	Battaglia M.A.,et al."Effects of water-soluble organic carbon on aerosol pH".Atmospheric Chemistry and Physics 19.23(2019).