title: Sources of formaldehyde and their contributions to photochemical O3formation at an urban site in the Pearl River Delta, southern China.
abstract: Two models (the Positive Matrix Factorization (PMF) model and a photochemical box model with Master Chemical Mechanism (PBM-MCM)) were applied to analyze the formaldehyde (HCHO) data collected in July 2006 at an urban site (GPEMC) in the Pearl River Delta (PRD), southern China. Three major HCHO sources (secondary formation, vehicular exhaust, and solvent usage) were identified and they were found to contribute in average 53%, 31% and 16% respectively to the total HCHO loading at GPEMC. Alkenes was the most important group contributing to the secondary formation of HCHO, followed by aromatics and alkanes. Among them, trans-2-butene had the largest contribution to secondary HCHO formation, with the average percentage of 16 ± 4%, followed by i-butene, cis-2-butene, propene, isoprene and m,p-xylene. Secondary HCHO and HCHO emitted from vehicular emissions contributed comparably to ground-based measured O3and HOxradical at GPEMC, higher than that from solvent usage (1.3 ± 0.1 ppbv and (4.1 ± 0.3) × 106molecule/cm3for O3and HOxradical). Our results highlight the importance of secondary HCHO formation for both photochemical formation of ozone and the oxidative capacity of the atmosphere in this region. It is hence critical for policy makers to propose strategies for controlling VOCs from vehicular emissions in order to reduce secondary HCHO formation. Our results also have important implication for improving the understanding of the source apportionments of HCHO and their contributions to photochemical pollution in the PRD region in China.
authors.affiliation: School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: Z H
authors.initials: ZH
authors.lastname: Ling
authors.affiliation: School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.affiliation: School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: S J
authors.initials: SJ
authors.lastname: Fan
authors.affiliation: School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, China. Electronic address: eeswxm@mail.sysu.edu.cn.
authors.forename: X M
authors.initials: XM
authors.lastname: Wang
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring; D005557:Formaldehyde / Q000032:analysis*; D010126:Ozone / Q000032:analysis / Q000737:chemistry*; D055668:Photochemical Processes; D012997:Solvents; D001335:Vehicle Emissions
chemical_list: D000393:Air Pollutants; D012997:Solvents; D001335:Vehicle Emissions; D005557:Formaldehyde; D010126:Ozone
keywords: Formaldehyde; Ozone; Pearl River Delta; Source apportionment