ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-7343-2009 Concurrent observations of air pollutants at two sites in the Pearl River Delta and the implication of regional transport Guo H. 1 Jiang F. 1 2 Cheng H. R. 1 Simpson I. J. 3 Wang X. M. 4 Ding A. J. 1 2 Wang T. J. 2 Saunders S. M. 5 Wang T. 1 Lam S. H. M. 5 Blake D. R. 3 Zhang Y. L. 1 4 Xie M. 1 2 Air Quality Studies, Department of Civil and Structural Engineering, the Hong Kong Polytechnic University, Hong Kong School of Atmospheric Sciences, Nanjing University, Nanjing, China Department of Chemistry, University of California at Irvine, California, USA Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China School of Biomedical, Biomolecular and Chemical Sciences, University of Western Australia, Perth, Australia 02 10 2009 9 19 7343 7360 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/9/7343/2009/acp-9-7343-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/7343/2009/acp-9-7343-2009.pdf

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<sub>3</sub>, NO<sub>x</sub>, CO, SO<sub>2</sub>, 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<sub>x</sub>. Thirteen O<sub>3</sub> episode days (daily O<sub>3</sub> 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<sub>3</sub> showed higher nighttime levels of O<sub>3</sub> 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<sub>3</sub> 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 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.

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