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Li X.,Tsinghua University | Wu Y.,Tsinghua University | Yao X.,Guangzhou Environmental Monitoring Center | Zhang S.,Tsinghua University | And 2 more authors.
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae

The short transient loaded mode (IG195) test can improve the efficiency of identifying high emitters in inspection/maintenance (I/M) programs. This paper was based on the pilot IG195 test data of light-duty gasoline vehicles (LDGV) in Guangzhou from 2007 to 2009. The percentages of high emitters exceeding the cut points for pre-and post-Euro I (including Euro I) vehicles were 20.1% and 17.6%, respectively. Re-inspection test data showed that 76.0% pre-Euro I and 64.7% post-Euro I high emitters could meet the requirement after proper maintenance. The modified MOBILE5 model was used to estimate the emission factors for LDGV. In 2009, the LDGV in Guangzhou emitted 244 thousand tons of CO, 38 thousand tons of HC and 18 thousand tons of NO x. If all of the vehicles which finally failed the IG195 test could be scrapped, the emissions of CO, HC and NO x can be reduced by 42.0 thousand tons, 5.8 thousand tons and 1.5 thousand tons, respectively, which amount to 17.2%, 15.3% and 8.2% of the total LDGV emissions. If all of the vehicles finally failing IG195 could be replaced by Euro IV models that complied with their emission standards, the emissions of CO, HC and NO x could be reduced by 41.2 thousand tons, 5.7 thousand tons and 1.4 thousand tons, which made up 16.9%, 15.0% and 8.0% of the total LDGV emissions, respectively. Controlling the pre-Euro I and Euro I vehicles was the most effective way in achieving emission reduction benefits by the new I/M program. The two vehicle categories together contributed about 90% of the emission reduction for CO and HC, and 85% for NO x in the I/M program. Source

Wang X.,CAS Guangzhou Institute of Geochemistry | Ding X.,CAS Guangzhou Institute of Geochemistry | Fu X.,CAS Guangzhou Institute of Geochemistry | Fu X.,University of Chinese Academy of Sciences | And 7 more authors.
Journal of Environmental Sciences

During November-December 2010 aerosol scattering coefficients were monitored using a single-waved (525 nm) Nephelometer at a regional monitoring station in the central Pearl River Delta region and 24-hr fine particle (PM 2.5) samples were also collected during the period using quartz filters for the analysis of major chemical components including organic carbon (OC), elemental carbon (EC), sulfate, nitrate and ammonium. In average, these five components accounted for about 85% of PM 2.5 mass and contributed 42% (OC), 19% (SO 4 2-), 12% (NO 3 -), 8.4% (NH 4 +) and 3.7% (EC), to PM 2.5 mass. A relatively higher mass scattering efficiency of 5.3 m 2/g was obtained for fine particles based on the linear regression between scattering coefficients and PM2.5 mass concentrations. Chemical extinction budget based on IMPROVE approach revealed that ammonium sulfate, particulate organic matter, ammonium nitrate and EC in average contributed about 32%, 28%, 20% and 6% to the light extinction coefficients, respectively. © 2012 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Source

Zhang Y.,CAS Guangzhou Institute of Geochemistry | Zhang Y.,University of California at Irvine | Wang X.,CAS Guangzhou Institute of Geochemistry | Blake D.R.,University of California at Irvine | And 10 more authors.
Journal of Geophysical Research: Atmospheres

In the second half of 2008 China's highly industrialized Pearl River Delta (PRD) region was hard-hit by the financial crisis (FC). This study reports volatile organic compounds measured in the PRD during November-December in both 2007 before the FC and 2008 after the FC. While total mixing ratios of non-methane hydrocarbons (NMHCs) on average were only about 7% lower from 40.2 ppbv in 2007 to 37.5 ppbv in 2008, their ozone formation potentials (OFPs) dropped about 30%, resulting from about 55% plummet of aromatic hydrocarbons (AHs) against a greater than 20% increase of total alkanes/alkenes. The elevated alkanes and alkenes in 2008 could be explained by greater emissions from vehicle exhausts and LPG combustion due to rapid increase of vehicle numbers and LPG consumption; the drop of AHs could be explained by reduced emissions from industries using AH-containing solvents due to the influence of the FC, as indicated by much lower ratios of toluene to benzene and of xylenes/ trichloroethylene/tetrachloroethylene to carbon monoxide (CO) in 2008. Source apportionment by positive matrix factorization (PMF) also revealed much less contribution of industry solvents to total anthropogenic NMHCs and particularly to toluene and xylenes in 2008 than in 2007. Based on PMF reconstructed source contributions, calculated OFPs by industrial emissions were responsible for 40.8% in 2007 in contrast to 18.4% in 2008. Further investigation into local industry output statistics suggested that the plummet of AHs in 2008 should be attributed to small enterprises, which contributed largely to ambient AHs due to their huge numbers and non-existent emission treatment, but were much more influenced by the FC. © 2012. American Geophysical Union. All Rights Reserved. Source

Gao B.,CAS Guangzhou Institute of Geochemistry | Gao B.,South China Institute of Environmental Sciences | Wang X.-M.,CAS Guangzhou Institute of Geochemistry | Zhao X.-Y.,CAS Guangzhou Institute of Geochemistry | And 10 more authors.
Atmospheric Environment

24-hPM2.5 samples were simultaneously collected at six sites in a subtropical city of South China during November-December, 2009. Particle-phase concentrations of polycyclic aromatic hydrocarbons (PAHs) and organic tracers such as hopanes for vehicular emissions (VE), levoglucosan for biomass burning (BB) and picene for coal combustion (CC) were determined. Meanwhile, their gas-phase concentrations were calculated from gas/particle (G/P) partitioning theory using the particle-phase concentrations. The 4 ring PAHs (fluoranthene to chrysene) had lower particle-phase fractions (10%-79%) than other species. Estimated BaPeq and lifetime cancer risk for particle-only (P-only) vs gas+particle (G+P) data sets showed similar values, indicating PAHs with 5-7 rings dominated the carcinogenicity of PAHs. Positive Matrix Factorization (PMF) was applied on both P-only and G+P data sets to estimate the source contributions to PAHs and their toxicity. Three common sources were identified: VE, BB and CC, with CC as the most significant source for both particulate (58%) and total (G+P, 40%) PAHs. While CC exhibited consistent contributions to BaPeq for P-only (66%) vs G+P (62%) solutions, VE and BB contributions were under- and overestimated by 68% and 47%, respectively by the P-only solution, as compared to the G+P solution. The results provide an insight on the impact of G/P partitioning on the source apportionment of PAHs and their toxicity. © 2014 Elsevier Ltd. Source

Zhang J.,Sun Yat Sen University | Zhang J.,Guangzhou Environmental Monitoring Center | Hu J.,Sun Yat Sen University | Wang X.,Sun Yat Sen University
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae

This paper mainly evaluated the ability of Ensemble Optimal Interpolation Data Assimilation Method (EnOI) in modifying the pollutants concentration forecast field in MM5-STEM air quality numerical model. Optimal settings of localization scale (L) and empirical coefficient (α) of NO2, SO2 and PM10 were acquired by sensitivity tests respectively. Assimilation results under these coefficient settings were analyzed, the results showed that EnOI had a good performance in the data assimilation experiments of NO2, SO2 and PM10, with RMSE decreasing percentage of 33%, 32% and 42%, respectively. The proportion of verification stations with decreased RMSE were 86%, 84% and 91%, respectively, which proved that EnOI produced a pollutant concentration forecast field closer to the true situation, therefore can be effectively applied in air quality modeling in the PRD. Source

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