Acidic gases, NH(3) and secondary inorganic ions in PM(10) during summertime in Beijing, China and their relation to air mass history.

In the summers of 2002-2003, acidic gases, ammonia and water-soluble ions in PM(10) were measured in Beijing. The mean concentrations of HCl, HONO, HNO(3), SO(2) and NH(3) are 0.6, 3.6, 1.9, 14.1 and 16.6microgm(-3), respectively, and 2.2, 14.6, 19.3 and 8.9microgm(-3) for Cl(-),NO(3)(-),SO(4)(2-)andNH(4)(+) in PM(10). The concentrations of secondary ions in PM(10) are found to have strong dependence on the pathway of trajectories. The most frequent southerly air flow is connected with high concentrations of secondary water-soluble ions during summertime. Other trajectories with northwest and north direction lead to lower concentrations of secondary ions. Hebei and Shandong Provinces and the Tianjin Municipality are the main source areas for sulfate as identified by Potential Source Contribution Function. This result emphasizes that the non-Beijing sources play an important role in the sulfate mass concentration in the urban atmosphere of Beijing and validates conclusions based on model calculations for the region.

[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.

[Determination and characteristics of OH radical in urban atmosphere in Beijing].

The measurement of atmospheric hydroxyl radicals (OH) in Beijing was carried out using two methods based on high performance liquid chromatography (HPLC). The diurnal variation of OH concentration was obtained. The maximum concentration during sunny daytime was about 8 x 10(7) cm-3 in summer, while it decreased to about 2 x 10(7)-4 x 10(7) cm-3 in autumn. The relationships between OH and other pollutants were studied and discussed. Positive linear correlation between OH and UV-B intensity, O3, HNO2 was observed, while negative correlation between OH and NOx was found.

Diurnal variations of aerosol chemical compositions and related gaseous pollutants in Beijing and Guangzhou.

A new apparatus, Steam Jet Aerosol Collector (SJAC) combined with on-line Mobile Ion Chromatograph provides a reliable way to measure both aerosol components and related gas species simultaneously. The SJAC was applied in the field campaigns in Beijing and Guangzhou to investigate aerosol chemical compositions and related gaseous pollutants. The concentration levels and diurnal variations are discussed, which implies differences in atmospheric chemistry of gas-to-particle conversions in Beijing and Guangzhou.

[Concentrations of aerosol and related gases in Beijing].

The measurement was made in 3 periods from May to September of 2000 in Beijing. The measurement species included SO4(2-), NO3-, NO2-, Cl- of aerosol and related gases. The hourly variation of the concentration was presented. It showed that NO3-, NO2-, Cl- of aerosol and HCl, HNO2, HNO3 of gas varied with regularity. The variation of gas SO2 and aerosol SO4(2-) depended on the emission of SO2. The peak time of SO4(2-) was about 2 hours later than SO2.