北京一次混合型重污染过程大气颗粒物元素组分分析

针对北京2013年1月的一次混合型大气重污染过程,于2012年12月31日—2013年1月18日在中国环境科学研究院大气环境研究所楼顶采集了TSP和PM₁₀样品,分析了其中的元素组分. 结果表明,逆温和静稳天气是导致此次大气污染的主要气象条件. 重污染期(2013年1月11—15日)北京大气ρ(TSP)和ρ(PM₁₀)的日均值分别为426.34和363.46 μg/m3,分别是非污染期(2013年1月2—6日)的3.5和3.4倍；而重污染期TSP和PM₁₀中ρ(无机元素)分别为36.38和18.67 μg/m3,是非污染期的2.2和1.6倍,低于颗粒物质量浓度升幅. 元素质量浓度特征和EF(富集因子)分析表明,Na、Mg、Al、K、Ca、Fe的质量浓度之和占总元素质量浓度的90%以上,其EF均小于10,属地壳类元素,重污染期各元素质量浓度未明显升高；Mn、Cr和Ni 3种元素的EF在研究过程中无明显变化；重污染期PM₁₀中w(Cd)(0.05%)、w(Zn)(3.34%)、w(As)(0.22%)、w(Pb)(3.54%)、w(Mo)(0.03%)、w(Sn)(0.14%)和w(Tl)(0.03%)明显升高,并且这7种元素重污染期与非污染期的质量浓度比值和EF都较高,其来源主要为燃煤、移动源、工业源和垃圾焚烧等人为源. 重污染期本地源对TSP和PM₁₀的贡献略有增加. 

Study on Elements in Aerosols during a Mixed Serious Pollution Episode in Beijing

To study a mixed serious pollution episode in Beijing in January 2013, TSP and PM₁₀ samples were collected on the roof of the Atmospheric Institute, Chinese Research Academy of Environmental Sciences, from December 31st, 2012, to January 18th, 2013. Elemental analysis results showed that the atmospheric pollution was induced under the meteorological conditions with temperature inversion and stable weather. The daily mean concentrations of TSP and PM₁₀ during the serious pollution period (January 11th to 15th) were 426.34 and 363.46 μg/m3, which were 3.5 and 3.4 times those during non-pollution period (2nd to 6th), respectively. Meanwhile, the total concentrations of inorganic elements in TSP and PM₁₀ during the serious pollution period (11th to 15th) were 36.38 and 18.67 μg/m3, which were 2.2 and 1.6 times those during non-pollution period and lower than the increases of total TSP and PM₁₀, respectively. Considering concentration characteristics and enrichment factor (EF), the crust-related elements represented by Na, Mg, Al, K, Ca and Fe had the highest mass concentration (>90%), and were not significantly increased during the serious pollution period. The EF of Mn, Cr and Ni not significantly vary during the studied episode. With higher concentration and greater EF, the elements Cd, Zn, As, Pb, Mo, Sn and Tl, whose mass fraction in PM₁₀ were 0.05%, 3.34%, 0.22%, 3.54%, 0.03%, 0.14% and 0.03% respectively, were mainly from coal-burning sources, vehicles, industrial source and waste incineration. In addition, the results also showed that the contribution of local sources slightly increased during serious pollution period.