Sources and atmospheric processes impacting oxalate at a suburban coastal site in Hong Kong: Insights inferred from 1year hourly measurements

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Title:	Sources and atmospheric processes impacting oxalate at a suburban coastal site in Hong Kong: Insights inferred from 1year hourly measurements
Authors:	谷邁世;Zhou, Yang;Huang, Xiaohui Hilda;Bian, Qijing;Griffith, Stephen M;Louie, Peter KK;Yu, Jian Zhen
Contributors:	地球科學學院大氣科學學系
Keywords:	Aerosols;Air masses;Air pollution;Anthropogenic factors;Atmospheric aerosols;Atmospheric chemistry;Atmospheric processes;Biomass;Biomass burning;Burning;Cluster analysis;Coastal;Commonality;Condensates;Condensation;Data;Dicarboxylic acids;Diurnal variations;Emissions;Gases;Geophysics;Human influences;Iron;Marine;Marine aerosols;Marine pollution;Meteorology;Nitrogen dioxide;Nuclei;Nucleus;Organic acids;Oxalates;Oxalic acid;Oxidation;Particulate emissions;Particulate matter;Photochemicals;Photochemistry;Photolysis;Pollution abatement;Ratios;Seasonal variations;Seasons;Summer;Sunrise;Suspended particulate matter;Trajectory analysis
Date:	2015-01-01
Issue Date:	2026-04-21 14:02:19 (UTC+8)
Publisher:	Wiley-Blackwell;Washington: Blackwell Publishing Ltd
Abstract:	摘要： Oxalic acid is one of the most abundant dicarboxylic acids in the atmosphere, receiving a great deal of attention due to its potential influence on cloud condensation nucleus activities. In this work, we report 10months of hourly oxalate measurements in particulate matter of less than 2.5 mu m in aerodynamic diameter (PM sub(2.5)) by a Monitor for Aerosols and Gases in ambient Air at a suburban coastal site in Hong Kong from April 2012 to February 2013. A total of more than 6000 sets of oxalate and inorganic ion data were obtained. The mean ( plus or minus SD) oxalate concentration was 0.34 ( plus or minus 0.18) mu gm super(-3), accounting for 2.8% of the total ion mass and 1.5% of the PM sub(2.5) mass. Seasonal variation showed higher concentrations in fall and winter (0.54 and 0.36 mu gm super(-3), respectively) and lower concentrations in spring and summer (~0.26 mu gm super(-3)). Different from the inorganic ions, a shallow dip in the oxalate concentration consistently occurred in the morning after sunrise (around 9:00 A.M.) throughout all seasons. Our analysis suggests that this was likely due to photolysis of oxalate-Fe (III) complex under sunlight. In summer, a small daytime peak was discernable for oxalate and nitrate. This characteristic, together with a more evident diurnal variation of O sub(3), indicates comparatively more active photochemical oxidation in summer than other seasons. High correlations were observed between oxalate and non-sea-salt SO sub(4) super(2-) (NSS) (R super(2)=0.63) and O sub(x) (O sub(3)+NO sub(2)) (R super(2)=0.48), indicating significant commonality in their secondary formation. Positive matrix factorization analysis of oxalate and other real-time gas and particle-phase component data estimates that secondary formation processes, including secondary gas or aqueous oxidation processes (49%), oxidation processes of biomass burning emissions (37%), accounted for the majority of PM sub(2.5) oxalate. A backward trajectories cluster analysis found that higher oxalate/NSS ratios were associated with low pollution samples under the influence of marine air masses while the ratios were lower in high pollution samples that were typically associated with continental air masses passing through areas of high anthropogenic emissions. Isolating the "low pollution marine" aerosols across the entire data set indicates that oxalate production increased in the summer compared to other seasons, suggesting either more active marine emissions of oxalate precursors or stronger photochemical processes in the summer. Key Points * Hourly measurements of PM sub(2.5) oxalate were reported for a suburban coastal site * Various secondary processes account for most oxalate * Photolysis of oxalate-Fe may explain a small dip of oxalate after sunrise 出版者： Washington: Blackwell Publishing Ltd 出版日期： 2015-09-01 出處： Journal of geophysical research. Atmospheres, 2015-09, Vol.120 (18), p.9772-9788 資源來源： Wiley Online Library - AutoHoldings Journals 版權： 2015. American Geophysical Union. All Rights Reserved. 識別號： ISSN: 2169-897X 識別號： EISSN: 2169-8996 識別號： DOI: 10.1002/2015JD023531
Appears in Collections:	[Department of Atmospheric Sciences] journal & Dissertation

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