Characteristics of PM 10, SO 2, NO x and O 3 in ambient air during the dust storm period in Beijing

Abstract

In this study, the hourly variations of the mass concentrations of PM 10, SO 2, NO x and O 3 at three sampling sites were observed in Beijing during dust storm occurrence period in April 2000. The PM 2.5 samples were simultaneously collected. By comparing the hourly variations of the pollutant concentrations before, during and after dust storm event and haze pollution episode, the variation characteristics of the mass concentrations of PM 10, SO 2, NO x and O 3 during dust storm events were presented. The results show that the mass concentration of PM 10 reached 1500 μg m −3 during dust storm events on April 6 and 25, 2000, which was 5–10 times that of the non-dust weather conditions, and this period of high mass concentration of PM 10 lasted for about 14 h, and then the concentration level prior to the dust event was recovered in 6-h time period. Due to the strong wind, the concentrations of SO 2, NO x , NO 2 and O 3 during dust storm period were maintained at low levels, which was significantly different from those on non-dust storm and haze pollution conditions. A lot of coarse particles as well as a very large amount of fine particles were contained in the atmospheric particulates during dust storm period, and the concentration level of PM 2.5 was comparable to that during haze pollution episode. During the dust storm period, the PM 2.5 concentration was approximately 230 μg m −3, accounting for 30% of the total PM 10 mass concentration, was four times that of non-dust weather conditions, and the crustal elements constituted about 66.4% of the chemical composition of PM 2.5 while sulfate and nitrate contributed much less, which was quite different from the chemical composition of PM 2.5 primarily constituted by sulfate, nitrate and organics on haze pollution day.