title: Trends of ambient fine particles and major chemical components in the Pearl River Delta region: observation at a regional background site in fall and winter.
abstract: In the fall and winter of 2007 to 2011, 167 24-h quartz filter-based fine particle (PM2.5) samples were collected at a regional background site in the central Pearl River Delta. The PM2.5 showed an annual reduction trend with a rate of 8.58 μg m(-3) (p<0.01). The OC component of the PM2.5 reduced by 1.10 μg m(-3) yr(-1) (p<0.01), while the reduction rates of sulfur dioxide (SO2) and sulfate (SO4(2-)) were 10.2 μg m(-3) yr(-1) (p<0.01) and 1.72 μg m(-3) yr(-1) (p<0.01), respectively. In contrast, nitrogen oxides (NOx) and nitrate (NO(3-)) presented growth trends with rates of 6.73 μg m(-3) yr(-1) (p<0.05) and 0.79 μg m(-3) yr(-1) (p<0.05), respectively. The PM2.5 reduction was mainly related to the decrease of primary OC and SO4(2-), and the enhanced conversion efficiency of SO2 to SO4(2-) was related to an increase in the atmospheric oxidizing capacity and a decrease in aerosol acidity. The discrepancy between the annual trends of NOx and NO3(-) was attributable to the small proportion of NO3(-) in the total nitrogen budget.
  Understanding annual variations of PM2.5 and its chemical composition is crucial in enabling policymakers to formulate and implement control strategies on particulate pollution.
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; Air Quality Studies, Department Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: Xiaoxin
authors.initials: X
authors.lastname: Fu
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. Electronic address: wangxm@gig.ac.cn.
authors.forename: Xinming
authors.initials: X
authors.lastname: Wang
authors.affiliation: Air Quality Studies, Department Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong. Electronic address: ceguohai@polyu.edu.hk.
authors.forename: Hai
authors.initials: H
authors.lastname: Guo
authors.affiliation: Air Quality Studies, Department Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: Kalam
authors.initials: K
authors.lastname: Cheung
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Ding
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Xiuying
authors.initials: X
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Quanfu
authors.initials: Q
authors.lastname: He
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Gao
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Tengyu
authors.initials: T
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000706:statistics & numerical data*; D002681:China; D004784:Environmental Monitoring; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D012621:Seasons
chemical_list: D000393:Air Pollutants; D052638:Particulate Matter
keywords: Carbonaceous aerosols; Nitrate; PM(2.5); Pearl River Delta; Sulfate