HALOGENTATED HYDROCARBONS IN THE ATMOSPHERE OF PEARL RIVER DELTA REGION, SOUTHERN CHINA

Halogenated hydrocarbons - manufactured as refrigerants and aerosol propellants - are main compounds that could destroy the stratospheric ozone layer and subsequently affect the climate change. On eight selected days between 25 October and 1 December, 2007, 198 whole air samples were simultaneously collected at two sites in the greater Pearl River Delta (PRD), namely Wan Qing Sha (WQS) in inland PRD and Tung Chung (TC) in Hong Kong, for the evaluation of halocarbons including chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and other chlorinated compounds. The mean mixing ratios of CFC-12, CH3CCl3, CH3Br, C2HCl3 and C2Cl4 at WQS were much higher than those at TC (p < 0.001), while HCFC-22 was higher at TC (p < 0.01). Long-lived species such as CFC-11, CFC-12 and CFC-113 showed similar temporal patterns on most sampling days with small daily variation, whereas the main species used as solvents such as C2HCl3 and C2Cl4 presented large daily variations though with consistent temporal patterns. Back trajectory analysis revealed that at both sites air masses originating from southern China had higher levels of C2HCl3 and C2Cl4 than those from the eastern China coast, whereas the mixing ratio of CCl4 was higher for air masses arriving at TC from the eastern China coast than from southern China, indicating different source regions for different halocarbon species. The results obtained in this study provide useful information to local government on effective control of halocarbon emissions in this region.