[Preliminary study on HOx photochemical processes in urban atmosphere of Guangzhou City].

Simultaneous measurements of atmospheric hydroxyl radicals (OH) and other pollutants in Guangzhou city were carried out in July, 2000. The quantitative analysis of HOx reaction cycle during daytime in summer was made. The calculation results indicated that the total production rates of OH and HO2 were about 4.5 x 10(8) OH/(cm3 x s) and 3.8 x 10(8) HO2/(cm3 x s), respectively. The primary OH source in urban atmosphere was the photolysis of HONO, while the main OH sinks were the reactions of OH with VOCs, HCHO, NO2 and CO. The HOx chemistry in urban atmosphere is quite different from that in the remote clean atmosphere.