Pollution Characteristics and Control Strategies of Atmospheric Photochemistry at a Comprehensive Site in Guangzhou, China

Guangzhou, one of China’s megacities, is beset with frequent occurrence of atmospheric photochemistry events. In this study, online instruments were used to simultaneously monitor VOCs, NOx and O₃ at Guangzhou Panyu Atmospheric Composition Station of the China Meteorological Administration, from June 2011 to May 2012, in order to obtain their characteristics, VOCs reactivity and the control strategies for atmospheric photochemistry. The results showed that during the observation period, the seasonal variation of O₃ concentration was lower in spring and winter compared to summer and autumn, which was opposite that for VOCs and NOx. In terms of VOCs, aromatics had the largest O₃ formation potential, among which toluene, xylenes, ethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethybenzene were the most important species, with a total contribution of about 44%. The sensitive-regime of O₃ production in the morning (6:00-9:00LT) mainly depended on how much the pollutants were affected by anthropogenic sources (i.e. vehicular emissions), but it was associated with the biogenic emissions at midday (10:00-16:00LT). NOx control was of importance for peak O₃ reduction in Guangzhou. Further investigation based on numerical models is needed in the future to obtain more detailed and robust conclusions.