冬季南京北郊大气气溶胶中水溶性阴离子特征

Characteristics of water-soluble anions in atmospheric aerosol in northern suburb of Nanjing in winter

2009年冬季在南京北郊进行24h采样,运用离子色谱法研究大气PM10中水溶性阴离子的分布特征。结果表明:PM10中阴离子的平均总质量浓度在白天和夜间分别为658.21、622.84μg/m3;PM2.1则分别为337.86、319.97μg/m3,阴离子主要存在于细粒子中;主要水溶性阴离子均为SO2-4,且海盐对南京北郊大气PM10和PM2.1中的SO2-4质量浓度影响很小。SO2-4、Cl-和F-粒径谱分布相似,均呈双模态;NO-3和NO-2主要呈现单模态。SO2-4与NO-3、F-与NO-3、SO2-4与Cl-的相关系数均大于0.8,相关显著,说明其存在一定的同源性。NO-3/SO2-4的平均值在白天、夜间分别为0.058 2、0.048 4,说明南京北郊大气污染以固定源为主。分析NO-3、SO2-4前体物的转化率知道,采样期间SOR和NOR的平均值均大于10%,即SO2-4部分来源于SO2的二次转化,而不是单一来源于一次污染物。

Aerosol PM10 of different sizes was collected the whole day in the northern suburb of Nanjing in winter 2009. This paper analyzes the distribution characteristics of water-soluble anions in PM10 by u- sing the ion chromatograph. Results show that the average total mass concentration of anions in PM10 （PM2.1） are 658.21 and 622. 84 μg/m3 （337.86 and 319.97 μg/m3） in daytime and nighttime,re- spectively, and anions dominate in the fine particles. SO2- are mainly water - soluble anions, and sea salt has little effect on the mass concentration of SO2- in PM10 and PM2.1 in the northern suburb of Nan- jing. The size distributions of SO42-, C1 - and F- show bimodal nature, while those of NO3- and NO2- show single mode. Correlation coefficients between SO42- and NO3 , F- and NO3- , SO42- and C1- are all greater than 0. 8, which are significant, indicating that these anions are homologous. The average NO3-/SO42 - in daytime and nighttime are 0. 0582 and 0. 0484, respectively, indicating that the air pollu- tion in northern suburb of Nanjing mainly comes from the stationary sources. Analysis of transformationof NO3- and SO2- precursors shows that the average SOR and NOR during the sampling period are more than 10%. It is show that SO2- in PM10 is partially come from the second photochemical transfor- mation of S02, rather than a single source of primary pollutants.