A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Photochemical evolution of organic aerosols observed in urban plumes from Hong Kong and the Pearl River Delta of China
Abstract Organic aerosols influence human health and global radiative forcing. However, their sources and evolution processes in the atmosphere are not completely understood. To study the aging and production of organic aerosols in a subtropical environment, we measured hourly resolved organic carbon (OC) and element carbon (EC) in PM2.5 at a receptor site (Tung Chung, TC) in Hong Kong from August 2011 to May 2012. The average OC concentrations exhibited the highest values in late autumn and were higher during the daytime than at night. The secondary organic carbon (SOC) concentrations, which were estimated using an EC-tracer method, comprised approximately half of the total OC on average. The SOC showed good correlation with odd oxygen (Ox = O3 + NO2) in the summer and autumn seasons, suggestive of contribution of photochemical activities to the formation of secondary organic aerosols (SOA). We calculated production rates of SOA using the photochemical age (defined as –Log10(NOx/NOy)) in urban plumes from the Pearl River Delta (PRD) region and Hong Kong during pollution episodes in summer and autumn. The CO-normalized SOC increased with the photochemical age, with production rates ranging from 1.31 to 1.82 μg m−3 ppmv−1 h−1 in autumn and with a larger rate in summer (3.86 μg m−3 ppmv−1 h−1). The rates are in the range of the rates observed in the outflow from Mexico City, the eastern U.S. and Los Angeles. Microscopic analyses of the individual aerosol particles revealed large contrasts of aerosol physico-chemical properties on clean and smoggy days, with thick organic coatings internally mixed with inorganic sulfate for all particle sizes in the aged plumes from the PRD region.
Highlights Hourly measurements of carbonaceous aerosols in Hong Kong are presented in this paper. Photochemical evolutions of organic aerosols were examined during the photochemical episodes. The SOC production rates ranged from 1.31 to 3.86 μg m−3 ppmv−1 h−1. Thick organic coatings were internally mixed with inorganic sulfate/nitrate in the aged plumes.
Photochemical evolution of organic aerosols observed in urban plumes from Hong Kong and the Pearl River Delta of China
Abstract Organic aerosols influence human health and global radiative forcing. However, their sources and evolution processes in the atmosphere are not completely understood. To study the aging and production of organic aerosols in a subtropical environment, we measured hourly resolved organic carbon (OC) and element carbon (EC) in PM2.5 at a receptor site (Tung Chung, TC) in Hong Kong from August 2011 to May 2012. The average OC concentrations exhibited the highest values in late autumn and were higher during the daytime than at night. The secondary organic carbon (SOC) concentrations, which were estimated using an EC-tracer method, comprised approximately half of the total OC on average. The SOC showed good correlation with odd oxygen (Ox = O3 + NO2) in the summer and autumn seasons, suggestive of contribution of photochemical activities to the formation of secondary organic aerosols (SOA). We calculated production rates of SOA using the photochemical age (defined as –Log10(NOx/NOy)) in urban plumes from the Pearl River Delta (PRD) region and Hong Kong during pollution episodes in summer and autumn. The CO-normalized SOC increased with the photochemical age, with production rates ranging from 1.31 to 1.82 μg m−3 ppmv−1 h−1 in autumn and with a larger rate in summer (3.86 μg m−3 ppmv−1 h−1). The rates are in the range of the rates observed in the outflow from Mexico City, the eastern U.S. and Los Angeles. Microscopic analyses of the individual aerosol particles revealed large contrasts of aerosol physico-chemical properties on clean and smoggy days, with thick organic coatings internally mixed with inorganic sulfate for all particle sizes in the aged plumes from the PRD region.
Highlights Hourly measurements of carbonaceous aerosols in Hong Kong are presented in this paper. Photochemical evolutions of organic aerosols were examined during the photochemical episodes. The SOC production rates ranged from 1.31 to 3.86 μg m−3 ppmv−1 h−1. Thick organic coatings were internally mixed with inorganic sulfate/nitrate in the aged plumes.
Photochemical evolution of organic aerosols observed in urban plumes from Hong Kong and the Pearl River Delta of China
Zhou, Shengzhen (author) / Wang, Tao (author) / Wang, Zhe (author) / Li, Weijun (author) / Xu, Zheng (author) / Wang, Xinfeng (author) / Yuan, Chao (author) / Poon, C.N. (author) / Louie, Peter K.K. (author) / Luk, Connie W.Y. (author)
Atmospheric Environment ; 88 ; 219-229
2014-01-15
11 pages
Article (Journal)
Electronic Resource
English
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