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Fan Q.,Sun Yat Sen University | Lan J.,Guangzhou Climate and Agrometeorology Center | Lan J.,Guangdong Ecological Meteorology Center | Liu Y.,Sun Yat Sen University | And 8 more authors.
Atmospheric Environment | Year: 2015

A numerical simulation analysis was performed for three air pollution episodes in the Pearl River Delta (PRD) region during March 2012 using the third-generation air quality modeling system Models-3/CMAQ. The results demonstrated that particulate matter was the primary pollutant for all three pollution episodes and was accompanied by relatively low visibility in the first two episodes. Weather maps indicate that the first two episodes occurred under the influence of warm, wet southerly air flow systems that led to high humidity throughout the region. The liquid phase reaction of gaseous pollutants resulted in the generation of fine secondary particles, which were identified as the primary source of pollution in the first two episodes. The third pollution episode occurred during a warming period following a cold front. Relative humidity was lower during this episode, and coarse particles were the major pollution contributor. Results of process analysis indicated that emissions sources, horizontal transport and vertical transport were the primary factors affecting pollutant concentrations within the near-surface layer during all three episodes, while aerosol processes, cloud processes, horizontal transport and vertical transport had greater influence at approximately 900 m above ground. Cloud processes had a greater impact during the first two pollution episodes because of the higher relative humidity. In addition, by comparing pollution processes from different cities (Guangzhou and Zhongshan), the study revealed that the first two pollution episodes were the result of local emissions within the PRD region and transport between surrounding cities, while the third episode exhibited prominent regional pollution characteristics and was the result of regional pollutant transport. © 2015 The Authors.

Ye C.-L.,CAS Anhui Institute of Optics and Fine Mechanics | Xie P.-H.,CAS Anhui Institute of Optics and Fine Mechanics | Qin M.,CAS Anhui Institute of Optics and Fine Mechanics | Ling L.-Y.,CAS Anhui Institute of Optics and Fine Mechanics | And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2012

In order to study the levels of BTX (benzene, toluene, xylene, etc) nearby the main roads of Guangzhou from November 2010 to December 2010 during the Asian Games, BTX and conventional pollutants such as NO2, O3 in the air were monitored by the DOAS system nearby Huangsha Road, which is in the Liwan District of Guangzhou City. The results showed that, during the entire period, BTX showed a high concentration in the evening and the average concentrations of benzene, toluene, p-xylene, m-xylene and phenol were 15.9 μg·m-3, 61.3 μg·m-3, 6.5 μg·m-3, 16.9 μg·m-3, 0.88 μg·m-3, respectively. The average concentrations of benzene and toluene were close to those in other cities, and the ratio of toluene to benzene was in range of 1.2- 6.16. Throughout the monitoring period, the correlation coefficient of benzene and toluene was 0.86 and it rose to 0.985 during the high concentration period, indicating that they had the same source in this region. The correlation coefficient between toluene and CO was 0.78, indicating that traffic emissions was the major source of benzene and toluene. Based on the combination of wind speed, wind direction and other meteorological data, it was found that the weather condition was an important factor which affected the BTX concentration, and some possible point sources were suggested nearby the site.

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