北京市大气颗粒物中全氟烷基化合物的粒径分布特征

杨朔; 陈辉伦; 盖楠; 路国慧; 郑宇; 邵鹏威; 杨永亮

doi:10.15898/j.cnki.11-2131/td.20180620074

北京市大气颗粒物中全氟烷基化合物的粒径分布特征

Particle Size Distribution of Perfluoroalkyl Substances in Atmospheric Particulate Matter in Beijing

摘要

摘要: 人为排放的持久性有机污染物倾向于在细级大气颗粒物中富集，但目前国内外关于大气颗粒物中全氟烷基化合物（PFASs）粒径分布在不同国家地区有显著差异，而在我国北京地区PFASs在不同粒径大气颗粒物中的富集能力尚不清楚。本文采用五级大流量主动分级采样器采集了北京市大气颗粒物样品，利用超声萃取结合高效液相色谱-电喷雾负电离源串联质谱测定PFASs含量，探讨了该地区大气颗粒物中PFASs的浓度水平和粒径分布特征，以及大气颗粒物浓度变化对PFASs浓度变化的影响。结果表明：研究区∑PFASs范围为10.1~62.9 pg/m³，76.4%~83.8%的PFASs集中分布在PM_2.5颗粒物中，其中含量较高的PFOA、PFNA和PFDA在<0.25 μm细颗粒物中占比最高，分别为26.3%~43.7%、30.3%~68.6%和30.6%~49.7%；PFOS在<0.25 μm细颗粒物中没有检出，主要分布在1~2.5 μm和0.25~1 μm颗粒物中。此外，研究发现北京市霾天大气颗粒物中∑PFASs为晴天的3.5倍，且不同粒径大气颗粒物浓度变化对PFASs各化合物表现出不同的富集能力，其中PFOA、PFOS、PFNA和PFDA等中链PFASs更易富集。

Abstract:
BACKGROUNDAnthropogenic emissions of persistent organic pollutants (POPs) tend to be concentrated in fine-level atmospheric particles. However, there are significant differences in the particle size distribution of perfluoroalkyl compounds (PFASs) in atmospheric particulate matter in different countries and regions, and the enrichment capacity of PFASs in different size particulate matter in Beijing is still unclear.
OBJECTIVESTo reveal the concentration level and particle size distribution characteristics of perfluoroalkyl substances in atmospheric particulate matter in Beijing, by collecting samples using a five stage impactor sampler and to discuss the effects of atmospheric particulate matter concentration changes on the concentration of perfluoroalkyl substances under different sizes.
METHODSThe samples were pretreated by ultrasonic extraction, and the concentrations of PFASs were determined by High Performance Liquid Chromatography-Electrospray Negative Ionization Source Tandem Mass Spectrometry.
RESULTSThe concentrations of ∑PFASs are 10.1-62.9 pg/m³, and 76.4%-83.8% of PFASs are concentrated in PM_2.5. PFOA, PFNA and PFDA have the highest concentration in the <0.25 μm particles, accounting for 26.3%-43.7%, 30.3%-68.6% and 30.6%-49.7%, respectively. PFOS is not detected in the fine particles (0.25 μm) and 68.9%-2.8% of PFOS are concentrated in the particles with sizes of 0.25-1 μm and 1-2.5 μm.
CONCLUSIONSThe ∑PFASs in the atmospheric particles of smog in Beijing are 3.5 times that of sunny days, and the changes of atmospheric particle concentration of different particle sizes show different enrichment ability for each compound of PFASs, among which PFOA, PFOS, PFNA and PFDA middle chain PFASs are enriched more easily.

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