杭州市PM_(2.5)中水溶性离子的污染特征及其消光贡献  

Pollution Characteristics and Light Extinction Contribution of Water-soluble Ions of PM_(2.5) in Hangzhou

作　　者：吴丹[1,2] 蔺少龙 杨焕强[3] 杜荣光[3] 夏俊荣[4] 齐冰[3] 刘刚[1,2] 李凤英[1,2] 杨孟[1,2] 盖鑫磊[1,2] 

机构地区：[1]南京信息工程大学江苏省大气环境与装备技术协同创新中心,南京210044 [2]南京信息工程大学江苏省大气环境监测与污染控制高技术研究重点实验室,南京210044 [3]杭州市气象局,杭州310051 [4]中国气象局气溶胶与云降水重点开放实验室,南京210044

出　　处：《环境科学》2017年第7期2656-2666,共11页Environmental Science

基　　金：江苏省自然科学基金项目(BK20130998);国家自然科学基金项目(41301581;91544220;41305118);浙江省自然科学基金项目(LY16D010006);南京信息工程大学基金预研项目(2014x003);杭州市社会发展科研专项(20150533B17)

摘　　要：对杭州市2013年大气PM_(2.5)进行采样分析,探讨了其中水溶性离子的污染特征和消光贡献.杭州市PM_(2.5)中总水溶性离子的质量浓度为37.5μg·m^(-3),占PM_(2.5)质量浓度的44.4%,二次离子SNA(SO_4^(2-)、NO_3^-和NH_4^+)是水溶性离子的主要成分,共占到水溶性离子的83.4%.PM_(2.5)和主要水溶性离子的质量浓度都在冬季最大,夏季最低,夏秋季水溶性离子占PM_(2.5)的比值明显高于冬春季,而SNA在总水溶性离子中的比例4个季节非常接近.燃料燃烧和汽车尾气排放导致的二次离子生成,对杭州市PM_(2.5)贡献最大.SOR和NOR的年平均值分别为0.27和0.15,SO_2在大气中的转化率大于NO_x,SOR和NOR与相对湿度都呈现出明显正相关,非均相氧化过程对SO_4^(2-)和NO_3^-的生成具有重要贡献.气溶胶中[NO_3^-]/[SO_4^(2-)]的年平均值为0.63,主要受到燃煤排放的影响.霾天随着霾污染等级的逐渐加重,PM_(2.5)、水溶性离子和SNA的浓度都逐渐增大,SOR和NOR值也不断升高,霾天稳定的天气条件,能有效促进污染物的积累和二次转化.PM_(2.5)和SNA的质量浓度与大气消光系数都呈现出明显正相关,使用IMPROVE公式对不同化学组分消光系数的计算结果能够基本反映出气溶胶对大气散射的变化趋势,其结果显示SNA对大气总消光系数的贡献达60.8%.SNA的消光系数冬季最高,夏季最低,随着霾污染等级的加重,SNA的消光系数和对总消光的贡献比例也逐步增加.The pollution characteristics and light extinction contribution of water-soluble ions of PM2.s in Hangzhou were investigated by sampling and laboratory analysis of aerosol samplers in 2013. The water-soluble ions were dominant in PM2.5 and the total mass concentration was 37.5 μg·m^-3, accounting for 44. 4% of the PM2.5 mass concentration. Water-soluble ions were mainly composed of secondary ions（ SO4^-- ,NO3 and NH4 ） , which accounted for 83.4% of total ions. The highest mass concentrations of PM2.5 and major ions were observed in winter and the lowest in summer. The proportions of water-soluble ions in PM2.5 in summer and autumn were obviously higher than those in winter and spring and proportions of secondary ions in water-soluble ions were very close in each season. The contribution was the greatest to PM2.5 from secondary ions generation caused by fuel combustion and automobile exhaust. The annual average values of SOR and NOR were 0. 27 and 0. 15 respectively, the conversion rate of SO2 in atmosphere was greater than that of NO. There was obvious positive correlation between SOR or NOR and humidity which indicated the important contribution of heterogeneous oxidation process to the generation of SO2^4- and NO3. The annual average of [ NO3^-]/[SO4^2-] was 0.63, and the aerosol pollution was primarily affected by emissions from coal burning. In haze days, with the increase of haze pollution level, the mass concentrations of PM2.5, water-soluble ions, secondary ions as well as SOR and NOR all increased gradually, and the stable weather condition in haze days could efficiently promote the accumulation and secondary conversion of pollutants. There were obvious positive correlations between mass concentrations of PM2.5 and SNA and the atmospheric light extinction coefficient. The IMPROVE formula which was used to calculate the light extinction coefficients of different chemical components could efficiently indicate the tendency of aerosol scattering. The extinction contribution of SNA could reach 60.8%. Th

关 键 词：PM2.5 水溶性离子 污染特征 霾 消光系数 

分 类 号：X513[环境科学与工程—环境工程]