Variability of organic and elemental carbon, water soluble organic carbon, and isotopes in Hong Kong

K.F. Ho (1) , S.C. Lee (1) , J.J. Cao (2) , Y.S. Li (1) , J.C. Chow (3) , J.G. Watson (3) , K. Fung (4)

1 Research Center for Urban Environmental Technology & Management
2 State Key Laboratory of Loess & Quaternary Geology
3 Division of Atmospheric Sciences
4 AtmAA Inc.

To determine the levels and variations of carbonaceous aerosol in Hong Kong, PM_2.5 and PM₁₀ samples were collected by high volume (Hi-vol) samplers at three monitoring stations (representing middle-scale roadside, urban-, and regional-scale environments) during winter (November 2000 to February 2001) and summer (June 2001 to August 2001) periods. The highest concentrations of organic carbon (OC), elemental carbon (EC), and water-soluble organic carbon (WSOC) were found at the middle-scale roadside site with the lowest at the regional-scale site. The percentages of WSOC in total carbon at these sites were inversely correlated with their concentrations (i.e., the highest percentages of WSOC were observed at the regional-scale site). A high WSOC fraction may be associated with aged aerosol because of the secondary formation by photochemical oxidation of organic precursors of anthropogenic pollutants during transport. The annual average of isotope abundances (?¹³C) of OC and EC were ?26.9±0.5? and ?25.6±0.1?, respectively. There were no notable differences for seasonal distributions of carbon isotopic composition, consistent with motor vehicle emissions being the main source contributors of carbonaceous aerosol in Hong Kong. OC ¹³C abundances at the regional-scale site were higher than those at the middle-scale roadside and urban sites, consistent with secondary organic aerosols of biogenic origin.

Domaines: Océan, Atmosphère

K.F. Ho, S.C. Lee, J.J. Cao, Y.S. Li, J.C. Chow, et al.. Variability of organic and elemental carbon, water soluble organic carbon, and isotopes in Hong Kong. Atmospheric Chemistry and Physics, 2006, 6 (12), pp.4569-4576. ⟨hal-00297186⟩