Abstract
Abstract. To assess the primary and secondary sources of fine organic aerosols after the aggressive implementation of air pollution controls during the 2008 Beijing Olympic Games, 12 h PM2.5 values were measured at an urban site at Peking University (PKU) and an upwind rural site at Yufa during the CAREBEIJING-2008 (Campaigns of Air quality REsearch in BEIJING and surrounding region) summer field campaign. The average PM2.5 concentrations were 72.5 ± 43.6 μg m−3 and 64.3 ± 36.2 μg m−3 (average ± standard deviation, below as the same) at PKU and Yufa, respectively, showing the lowest concentrations in recent years. Combining the results from a CMB (chemical mass balance) model and secondary organic aerosol (SOA) tracer-yield model, five primary and four secondary fine organic aerosol sources were compared with the results from previous studies in Beijing. The relative contribution of mobile sources to PM2.5 concentrations was increased in 2008, with diesel engines contributing 16.2 ± 5.9% and 14.5 ± 4.1% and gasoline vehicles contributing 10.3 ± 8.7% and 7.9 ± 6.2% to organic carbon (OC) at PKU and Yufa, respectively. Due to the implementation of emission controls, the absolute OC concentrations from primary sources were reduced during the Olympics, and the contributions from secondary formation of OC represented a larger relative source of fine organic aerosols. Compared with the non-controlled period prior to the Olympics, primary vehicle contributions were reduced by 30% at the urban site and 24% at the rural site. The reductions in coal combustion contributions were 57% at PKU and 7% at Yufa. Our results demonstrate that the emission control measures implemented in 2008 significantly alleviated the primary organic particle pollution in and around Beijing. However, additional studies are needed to provide a more comprehensive assessment of the emission control effectiveness on SOA formation.
Highlights
GeoscientificWith rapid ecoMnoomdicedleDveleopvmeelnot pamnd einnctreasing energyM ical mass balance) model and secondary organic aerosol consumption, Beijing has experienced severe air pollution (SOA) tracer-yield model, five primary and four secondary fine organic aerosol sources were compared with the results from previous studies in Beijing
Due to the implementation of emission controls, the absolute organic carbon (OC) concentrations from primary sources were reduced during the Olympics, and the contributions from secand has become one of the hotspots for air pollution in the world (Shao et al, 2006H).yItdhraos lboeegnyreaponrtded that ambient particles, especially tant air pollutant in BfineeijimnEgoad(eGrtpuhaorteSitclyaelss.,ta2er0em1t0h;eHmuoasnt dimGpuoor, 2009; Chan and Yao, 2008)
A total of 12 h ambient PM2.5 samples were collected during the CAREBEIJING-2008 (Campaigns of Air quality REsearch in BEIJING and surrounding region) summer field campaign from 16 July to 31 August 2008, using fourchannel samplers (TH-16A, Tianhong, China) simultaneously at an urban site, located on the campus of Peking University (PKU: 39◦59 21 N, 116◦18 25 E), and an upwind rural site in Yufa, located 53 km south of PKU (39◦30 49 N, 116◦18 15 E)
Summary
M ical mass balance) model and secondary organic aerosol consumption, Beijing has experienced severe air pollution (SOA) tracer-yield model, five primary and four secondary fine organic aerosol sources were compared with the results from previous studies in Beijing. Organic tracers have been utilized in several fine particle source apportionment studies in Beijing (Zheng et al, 2005; Wang et al, 2009). Zheng et al (2005) and Wang et al (2009) quantified the source contributions to fine mode particles in the years of 2000 and 2005 to 2007, respectively, using a molecular marker chemical mass balance (CMB) model. A chemical mass balance (CMB) model and a SOA tracer-yield model were employed to apportion the primary and secondary particulate organic matter sources. The results were compared with previous studies to explore possible emission changes of particulate matter sources in the recent years. Emission control effectiveness during the different control periods was evaluated by investigating the variations of primary and secondary particulate organic sources. The results from this study provide a baseline data set for regional air quality models to improve the understanding of the impacts of various emission controls on air quality
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