Concurrent observations of air pollutants at two sites in the Pearl River Delta and the implication of regional transport

Abstract

Abstract. An intensive field measurement study was conducted simultaneously at a site within the inland Pearl River Delta (PRD) region (WQS) and a site in Hong Kong (TC) between 22 October and 1 December 2007. Ambient air pollutants measured included O 3 , NO x , CO, SO 2 , NMHCs, and carbonyls. The purpose is to improve our understanding of the interplay among local and regional air pollutants in the Hong Kong area, and the influence of regional transport on local air pollutants. The results indicate that the mean levels of air pollutants at the WQS site were much higher than those at the TC site, except NO x . Thirteen O 3 episode days (daily O 3 peak in excess of 122 ppbv) were monitored at WQS during the study period, while only 2 days were recorded at TC. Diurnal variations of O 3 showed higher nighttime levels of O 3 at TC than at WQS as well as more photochemical activity at WQS than TC. Remarkable differences in diurnal variations were also found between high and low O 3 pollution days at each site, implying that Hong Kong is more acutely VOC-limited than the inland PRD region. Ratio analyses for trace gases and VOCs and back trajectory calculation revealed that the air masses arriving at WQS were more aged due to regional influence, whereas the air masses at TC were mainly affected by local emissions and/or regional transport. In addition, the influence of regional transport from Eastern China on the primary pollutants of Hong Kong was noticeable, whereas the air masses from the inland PRD region (e.g. Dongguan and Huizhou) had significant influence on the air pollutants at WQS, and the anthropogenic emissions Correspondence to: H. Guo (ceguohai@polyu.edu.hk) in Eastern PRD (e.g. Shenzhen) played an important role on the photochemical ozone pollution in Western Hong Kong. These results confirm that regional and sub-regional transport of air pollution has a complex and significant impact on local air pollutants in this region.

Polycyclic aromatic hydrocarbons in PM2.5 in Guangzhou, southern China: Spatiotemporal patterns and emission sources

“…Studies have shown that cities in this region suffer from regional air pollution [11][12][13]. As one class of persistent organic pollutants, PAHs can undergo long range atmospheric transport.…”

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

“…The local anthropogenic emissions were thus not significant, with most air pollutants originating from the surrounding cities. The site was 50 km southeast of Guangzhou center, 40 km southwest of Dongguan, 50 km northwest of Shenzhen, and 25 km northeast of Zhongshan, making it a good regional station to characterize the air pollution of the inner PRD (Guo et al, 2009). The PM 2.5 high-volume samplers (Tisch Environmental Inc., USA) were placed on the rooftop of a building, about 30 m above the ground.…”

Long-term O<sub>3</sub>–precursor relationships in Hong Kong: field observation and model simulation

“…Trends of O 3 and its precursors with a p value < 0.05 were considered significant (Guo et al, 2009). …”

“…Hong Kong, together with the inland Pearl River Delta (PRD) region of southern China, has suffered from high O 3 mixing ratios in recent years (Chan et al, 1998a, b;Wang and Kwok, 2003;Ding et al, 2004;Zhang et al, 2007;Guo et al, 2009Guo et al, , 2013. In 2014, O 3 exceeded the Chinese national air quality standard (80 ppbv, for the daily 8 h maximum average, DMA8) on more than 90 days in some areas of the PRD, with the highest DMA8 value of 165 ppbv (GDEMC and HKEPD, 2015).…”