| As one of the most important composition in air, aerosol has an siginificant influence on urban environment, climate change, and human health. Aerosol could increase the haze event, decrease the visibility, and aggravate cardiovascular or pulmonary disease triggered by inflammation when ultrafine particles go through lung. It’s mostly depended on arrosol’s size distribution and chemistry when particles tranmit, transform and remove among the atmosphere, that the effects of particles on solar radiation, and whether or not to become the clound condensation nucleus. So it’s conducive to analyse the effects of aerosol on radiation balance, chemistry processe and local environment vation, and provide some rational controls about air pollution when we know the aerosol character and sources.In this study, we measured the aerosol number concentration, mass concentration, pollution gas oncentration and water-soluble ions combing the meteorology elements by Wide Range Particle Spectrometer (WPS), Scanning Mobility Particle Size (SMPS), Andersen-Ⅱ-type9crash sampler, β ray continuous ambient particulate monitor, Differential Optical Absorption Spectroscopy (DOAS), Thermo Fisher Scientific EMS (EMS) and ion chromatography. The aerosol characteration variation are discussed under three important pollution weather (crop burning, long range dust transmission, firework burning) leading to the air quality deterioration in Nanjing. The condition of new particle formation (NPF) and its relation with precursor gas are analysed combing the observation data in Taishan, the differences and similarities of NPF events are compared between the two clean and pollution distributes.The spectral distributions of aerosol number have significantly seasonal and diurnal variation:number concentrations in the size range between10-30nm are summer>spring>autumn, summer>autumn>spring for particles between30-100nm, spring>autumn>summer for particles larger than1μm. The diurnal variations show trimodal distribution for the three seasons, with the peak time at8:00～9:00,12:00～14:00and19:00～20:00respectively. Aerosol size distribution and diurnal varion of number concentration are consistent among Jiangbei industry aera, Gulou business aera and Zhongshan scenic aera. The aerosol mass spectrum show bimodal distribution, with the peaks at0.43～0.65μm and9.0～10.0μm for three seasons and are consistent among different function aeras in Nanjing. The concentration of PM10and PM2.1have obviously changes among different seasons, autumn>spring>summer and have large differences among different function, traffic source> industry aera> business aera>scenic aera.The effects of crop buring on SO2are the biggest, followed by NO2and the smallest on O3. Fine particles are influenced larger than coarse particles by crop burning. The fine particles’ concentration is222.9μg/m3on pollution days which is2.2times larger than that on normal days, the coarse particles’concentration is122.9μg/m3on pollution days, which is1.2times larger than that on normal days. The crop buring have significant influences on the size distributions of K+, Cl-, Na+, F", and little influences on NH4+, Ca2+, NO3-and SO42-.The coarse particles’number concentration could increase up to50cm"3on dust days, which is2.23times larger than that on normal days. The nuclea mode particles’concentration could increase up to13237cm-3during NPF events, which is4.31times larger than that on normal days. Aerosol number spectrum show a unimodal distribution, with the peak at20nm during NPF periods, and show a bimodal distribution on dust, precipitaion and sunny days, with peaks at20-40nm and70-100nm. Particles’mass concentration larger than2.1μm are mainly influenced by dust weather, but water-soluble ions are hardly affected.The aerosol number concentrations have a big variation during the workfire burning periods. Particles’concentrations in the diameter of10-20nm and20-50nm decreased, Particles’ concentrations of50-500nm increased, with the value of4377cm’3and1422cm-3in the diameter of100-200nm and200-500nm respectively, which is2.15and1.65times larger than those on normal days. Particles’concentrations of0.5-10μm didn’t have obvious change. The burning of firework could sharply elevate PM10, decrease the visibility, and had large effects on the mass concentration of fine particles below1.1um and water-soluble ions’concentration. The mass spectrum and ions’spectrum had trimodel distributions during the forework burning periods, and bimodal distributions on non-burning periods. During the firework burning periods, the concentration of K+ion elevated, the proportion K+, SO42-, NO3", Cl-and Mg2+in PM2.1and PM1.1increased by16%-38%compared by those in non-burning days, the rest ions had no influence.The NPF events occurred with an eastern wind, high relative humidity (50%-70%), strong solar radiation (400-700W·m-2) in summer, and occurred with an northern wind, low relative humidity (14%-30%), strong solar radiation (400-600W-m-2) in spring. However, there was no phenomenon of NPF events because of severe pollution in autumn of Nanjing. Aerosol concentration in10-25nm had positive correlations with SO2and NO2and had negtive correlations with O3and NO2+O3during NPF event in summer, concentration in10-25nm had negtive correlations with SO2, NO2and NO2+O3, and had positive correlations with O3during NPF event in spring. During the developing and aging process of NPF, there were large differences between concentration in10-25nm and pollution gases. The growth rate of particles’ size in Huang Mountain was fast than that in Nanjing, meanwhile, the airmass were clean and from marine and district with low ultrafine particles. |
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