杭州市冬季大气气溶胶PM2.5中二恶英和多氯联苯的污染特征

2014年1月在杭州市选择5个点位采集大气颗粒物PM_2.5样品，采用同位素稀释高分辨气相色谱/高分辨质谱测定PM_2.5中的二恶英（PCDD/Fs）和多氯联苯（PCBs），对PM_2.5的污染状况以及PM_2.5中PCDD/Fs和PCBs的污染水平及分布特征进行了研究。PM_2.5的质量浓度范围为85~168 μg/m³，PM_2.5污染较重，但与2004年同期相比明显降低。PM_2.5中PCDD/Fs的毒性当量（TEQ）为0.277~0.488 pg I-TEQ/m³，明显高于2004年同期采集样品。颗粒物中PCDD/Fs以八氯代二苯并-对-二恶英（OCDD）为主，毒性当量主要贡献者为2，3，4，7，8-五氯代二苯并呋喃（2，3，4，7，8-PeCDF）。PM_2.5中PCBs的质量浓度范围为2.9~8.1 pg/m³，二恶英类多氯联苯（DL-PCBs）的毒性当量范围为2.6~6.1 fg WHO-TEQ/m³，污染较低。PCBs在颗粒物中分布以PCB-28为主，但对毒性当量贡献最大的为PCB-126。PCDD/Fs和PCBs的气-固分配特征表现为PCDD/Fs主要分布于颗粒物中，而PCBs主要分布于气相中。

Pollution characteristics of polychlorinated dibenzo-p-dioxins,polychlorinated dibenzofurans and polychlorinated biphenyls in PM2.5 of Hangzhou City during winter

In order to evaluate the distributions and concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in aerosol, PM_2.5 samples were collected concurrently at five sites in January 2014 in Hangzhou. The analytes were analyzed with isotope dilution and high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) based on US EPA 1613B method and US EPA 1668B method. The results showed that the mass concentrations of PM_2.5 were in the range of 85-168 μg/m³, which were much higher than the national quality standard. The values suggested that the PM_2.5 pollution was relatively serious in Hangzhou City, yet it has been improved when compared with the results of 2004. The toxic equivalent quantities (TEQs) of PCDD/Fs in PM_2.5 were in the range of 0.277-0.488 pg I-TEQ/m³, which were much higher than the results in 2004. Octachlorodibenzo-p-dioxin(OCDD) accounted for a large proportion to the total concentrations in PCDD/Fs, while 2,3,4,7,8-pentachlorodibenzofurans (2,3,4,7,8-PeCDF) contributed the highest to the TEQ. The values of PCBs and dioxin-like PCBs (DL-PCBs) varied from 2.9-8.1 pg/m³ and 2.6-6.1 fg WHO-TEQ/m³, respectively. PCB-28 was the most abundant contributor to the concentrations of PCBs, while PCB-126 contributed the highest to the TEQ of DL-PCBs. Gas-particle distributions of PCDD/Fs and PCBs shows that PCDD/Fs were mainly distributed in the particle phase, but PCBs were preferably adsorbed in the gas phase.