北京市和南京市采暖期不同粒径大气颗粒物水溶性阴阳离子的比较研究

Comparison of the concentrations of water-soluble ions in atmospheric particles with different sizes in Beijing and Nanjing during the heating period

目的了解采暖期北京市和南京市大气颗粒物的粒径谱以及不同粒径颗粒物水溶性阴、阳离子浓度的差别。方法于2015年11月23日—2015年12月17日在北京市和南京市分别使用PSW-8型气溶胶粒度分布采样器采集大气颗粒物,并采用重量法和离子色谱法分别测定大气中颗粒物的浓度和不同粒径颗粒物水溶性阴阳离子的浓度。结果北京市大气颗粒物的总浓度高于南京市,且粒径小于2.1μm的颗粒物的质量占总颗粒物的比例均大于63.5%。除了Ca^(2+)的浓度,北京市大气颗粒物中F^-、Cl^-、SO_4^(2-)、NO_3^-、Na^+、NH_4^+、K^+和Mg^(2+)的浓度均高于南京市。大气颗粒物中NH_4^+、SO_4^(2-)和NO_3^-的含量较高,主要富集于粒径小于2.1μm的颗粒物中,Mg^(2+)、Ca^(2+)和F^-主要富集于粒径大于2.1μm的颗粒物中。北京市不同粒径颗粒物中NO_3^-和SO_4^(2-)的比值范围为0.75~1.01,南京市为1.20~1.55。结论采暖期两个城市大气颗粒物中水溶性离子的主要来源不同,两个城市水溶性离子在不同粒径颗粒物上分布规律一致。

Objective To know the difference of water-soluble ions concentrations in atmospheric particles with different sizes between Beijing and Nanjing in heating period.Methods PSW-8 sampler was used to collect atmospheric particles in Beijing and Nanjing from Nov 23,2015 to Dec 17,2015.The gravimetric method and ion chromatography were used to determine the concentrations of particles and ions respectively.Results The mass concentration of total atmospheric particles in Beijing was higher than that in Nanjing.The percentage of particles with diameter of less than 2.1 μm was more than 63.5%.Except Ca^(2+),the mass concentrations of F^-,Cl^-,SO_4^(2-),NO_3^-,Na^+,NH_4^+,K+and Mg^(2+)in Beijing were higher than those in Nanjing.NH_4^+,SO_4^(2-)and NO_3^-were the three main ions in particles were enriched in particles with diameter of less than 2.1 μm,whereas,Mg^(2+),Ca^(2+)and F-were mainly distributed in coarse particles.The ratio ranges of NO_3^-and SO_4^(2-)in particles between Beijing and Nanjing were 0.75~1.01 and 1.20~1.55 respectively.Conclusion The main sources of water-soluble ions between Beijing and Nanjing are different in heating period,although the water-soluble ions of the two cities have the same distribution characteristics in particles with different diameters.