Abstract
Using the data on aerosol observed hourly by Marga ADI 2080 and Grimm 180, we compared the characteristics of aerosol during rainy weather and cold air-dust weather in Guangzhou in late March 2012. The mass concentration of aerosol appeared distinct between the two weather processes. During rainy weather, the mass concentration of PM and total water-soluble components decreased obviously. During cold air-dust weather, the cleaning effect of cold air occurred much more suddenly and about a half day earlier than the dust effect. As a result, the mass concentration of PM and total water-soluble components first dropped dramatically to a below-normal level and then rose gradually to an above-normal level. The ratio of PM2.5/PM10 and PM1/PM10 decreased, suggesting that dust-storm weather mainly brought in coarse particles. The proportion of Ca2+ in the total water-soluble components significantly increased to as high as 50 % because of the effect of dust weather. We further analysed the ionic equilibrium during rainy and cold air-dust weather, and compared it with that during hazy weather during the same period. The aerosol during rainy weather was slightly acidic, whereas that during hazy weather and cold air-dust weather was obviously alkaline, with that during cold air-dust weather being significantly more alkaline. Most of the anions, including SO4 2− and NO3 −, were neutralised by NH4 + during rainy and hazy weather, and by Ca2+ during cold air-dust weather.
Highlights
Aerosol plays an important role in the change in global climate system and the formation of regional air pollutants
Shen et al (2012) analysed the dust storm transported from Mongolia to Guangzhou in April 2009 and suggested that the mass concentration of PM10 obviously rose along with various water-soluble components, but the total proportion of SO42−, NO3− and NH4+ remained stable (~82 %)
For relative humidity (RH), from March 16th to 18th, it increased to 100 %, indicating that rainfall might happen
Summary
Aerosol plays an important role in the change in global climate system and the formation of regional air pollutants. Shen et al (2012) analysed the dust storm transported from Mongolia to Guangzhou in April 2009 and suggested that the mass concentration of PM10 obviously rose along with various water-soluble components, but the total proportion of SO42−, NO3− and NH4+ remained stable (~82 %). These previous studies explored the characteristics of aerosol during dusty weather, but their observed data were inconclusive. The concentrations of PM2.5 and total watersoluble components decreased dramatically whereas Ca2+ obviously increased from March 23rd This result indicates that, on the one hand, the occurrence of cold air could act as.
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