| Atmospheric aerosol chemical composition is very complex, particle size distribution range is very wide, in different particle size range, different chemical composition of aerosol particles show different characteristics. The chemical composition of different sources of aerosols is also different, so the characteristics of chemical composition, the source of the solution to solve the complexity of aerosols is essential. In this study, the Anderson Nine Impact Sampler, Wuhan Tianhong Flow Sampler were used in the northern suburbs of Nanjing, and the organic carbon in atmospheric particles was analyzed by Model 2001A thermo-optical carbon analyzer and water-soluble ion chromatography , The concentration of elemental carbon and water-soluble ions were measured, and the observed results were compared with different meteorological factors in different seasons and different weather conditions.The results show:The observations under strict control measures were divided into three types of weather, sunny, rainy and cloudy. The average concentrations of PM2.5 under different weather conditions were sunny > cloudy > rainy days. The concentrations of water soluble ions in PM1.1, PMi1.1-2.1 and PM2.1-10 were also sunny > cloudy >rainy days, and the obliterate of fine particles by precipitation process was more obvious. The spectral of Ca2+ and Mg2+ were bimodal. The scavenging effect of SO42- and NH4+ during 0.65?1.1?m were stronger. .The ratio of NO3-/SO42- under different weather conditions were less than 1,and the ratio of NO3-/SO42- in rainy and cloudy days was higher than that in sunny days. The values of SOR and NOR in the three kinds of weather conditions are more than 0.1 , SO2 and NO2 have different degrees of transformation, there are more secondary pollutant in the atmosphere.The average concentration of PM2.5 was 55.98?g·m-3, The secondary ions (NH4+?NO3- and SO42-) accounted for 63.89%,which was the most important pollution component in PM2.5 in the northern suburb of Nanjing. Affected by the transmission of air mass and meteorological conditions, OC and EC concentrations were highest in winter and lowest in summer, and the day of the concentration of OC in the four seasons was lower than that at night. The correlation of EC and OC in autumn and summer was better but in spring and winter correlation was weak. Indicating that the in autumn and summer EC and OC mainly from a similar source,while the sources of winter and spring were relatively complex. The OC / EC of the four seasons were greater than 2, indicating the presence of secondary reactions for the formation of organic carbon. The OC / EC ratios in autumn,winter and spring were 4.94 ± 1.52,7.17 ± 3.28 and 5.93 ± 2.5, respectively. Indicating that the the OC and EC of PM2.5 in autumn, winter and spring have sources come from coal combustion. The OC / EC ratio for summer night was 3.85 ± 1.34, indicating that there was exhaust emissions from diesel and petrol vehicles during the summer night. K+/OC of the autumn average was 0.09, significantly higher than the other three seasons, indicating that biomass combustion in the fall of the largest contribution.The PMF model was used to analyze the source apportionment of PM2.5 in the northern suburb of Nanjing, and the five factors were the best results: secondary aerosol, vehicle exhaust as the main pollution, followed by dust, biomass fuel and coal combustion .The The average contribution rates of biomass combustion source,secondary aerosol source,coal combustion source,vehicle exhaust source and dust source to PM2.5 were 10.77%, 32.39%, 8.67%, 32.10% and 16.07% respectively. |
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