天津市大气中全氟化合物挥发性前体物的分布和季节变化

The atmospheric distribution and seasonal variation of volatile perfluoroalkyl substance precursors in Tianjin

城市是全(多)氟烷基化合物(Per-and polyfluoroalkyl substances,PFASs)典型的来源地区,本研究利用大流量主动采样器对天津市3个典型位点的大气分别在冬夏两季进行了短期连续监测.发现PFASs的挥发性前体物氟调聚醇(Fluorotelomer alcohols,FTOHs)在天津地区的市中心、乡村和污水处理厂位点的大气中均普遍检出,其总浓度(气态+颗粒态)在冬、夏两季分别达到25.6—95.3 pg·m^(-3)和16.7—2003 pg·m^(-3),中位值分别为71.6 pg·m^(-3)和50.6 pg·m^(-3),其中最高浓度出现在市中心位点;而对于全氟辛烷磺酰胺类化合物(Perfluorooctane sulfonamide derivatives,PFOSAs),除在两个样品中有N-乙基全氟辛烷磺酰胺超过100 pg·m^(-3),在大部分样品中均未检出PFOSAs或显著低于FTOHs的浓度.本研究发现,FTOHs在冬、夏季间发生了显著的相间转化,在夏季FTOHs主要存在于气相,因而可能具有较高的长距离迁移潜力;而在冬季颗粒态FTOHs所占比重显著增加,因而其大气迁移和转化能力可能更多地受到大气颗粒物的影响.在大气总悬浮颗粒物浓度较高的天津地区,颗粒态FTOHs的贡献不可忽视.

City is a typical source region of per- and polyfluoroalkyl substances（ PFASs）. In the present study, high-volume air samplers were deployed at three typical sites in Tianijn to simultaneously monitor the atmospheric concentrations of the volatile precurors of PFASs in the winter and summer. Fluorotelomer alcohols（ FTOHs） were generally detected at the city center site,rural site and wastewater treatment plant site. As a whole,the concentration ranges of FTOHs were25. 6—95.3 pg·m^-3（ median 71.6 pg·m^-3） and 16.7—2003 pg·m^-3（ 50.6 pg·m^-3） in the winter and summer campaigns,respectively. Perfluorooctane sulfonamide derivatives（ PFOSAs） were either below the detection limit or at a much lower level compared to FTOHs,except that N-ethylperfluorooctane sulfonamide was detected at levels over 100 pg·m^-3 only in two samples. In the summer,FTOHs primarily occurred in the gas phase and showed higher long-range-transport（ LRT）potential. In the winter,the contribution of particle-phase FTOHs substantially increased and the LRT and degradation potential were likely more influenced by atmospheric particulate matter. The atmospheric concentrations of total suspended particles were relatively high in Tianjin and the contribution of particle-phase FTOHs cannot be ignored.