太原市环境空气中挥发性芳香烃碳同位素组成及来源

Stable Carbon Isotope Compositions and Source Apportionments of Volatile Aromatic Compounds in the Urban Atmosphere of Taiyuan,China

利用Tenax TA吸附管采集太原市不同排放源及不同功能区环境空气样品,色谱-质谱、同位素质谱联用技术测定了其挥发性芳香烃化合物的碳同位素组成,并分析了其组成特征.结果表明,柴油挥发源、汽油挥发源、溶剂挥发源、机动车尾气源和民用燃煤源排放的挥发性芳香烃化合物中稳定碳同位素值(δ13C)测定范围依次为:(-30.79±0.98)‰^(-29.10±0.14)‰、(-30.96±0.88)‰^(-28.02±1.77)‰、(-32.13±0.59)‰^(-27.67±0.49)‰、(-27.58±0.16)‰^(-25.50±0.75)‰和(-25.14±0.93)‰^(-23.44±1.32)‰,民用燃煤源显著富集13C.仅在民用燃煤源排放烟气中检出苯乙烯,δ13C值为(-23.44±1.32)‰.太原市4个不同功能区采样分析显示,居民交通混合区环境空气中挥发性芳香烃的δ13C值为(-25.61±2.20)‰^(-23.91±0.78)‰,较其他区域富集13C;工业区δ13C检测值为(-29.15±1.06)‰^(-24.53±1.07)‰,较其他区域贫13C.将环境空气中挥发性芳香烃δ13C值与排放源δ13C值比较可发现,太原市4个环境空气点位的挥发性芳香烃主要来源是机动车尾气源和民用燃煤源,工业区受溶剂挥发影响较大.

This study used Tenax TA absorption tubes to sample volatile aromatic compounds from different emission sources and functional zones in Taiyuan City,Shanxi Province,China. Thermal desorption-gas chromatography-isotope ratio mass spectrometry( TD-GC-IRMS) was subsequently employed to analyze the stable carbon isotope characteristics of the volatile aromatic compounds. The results revealed that the stable carbon isotope ratio(δ13C) of the volatile aromatic compounds emitted through diesel,gasoline,and solvent volatilization,vehicle exhaust,and domestic coal combustion ranged from(-30. 79 ± 0. 98)‰ to(-29. 10 ± 0. 14)‰,(-30. 96 ± 0. 88)‰ to(-28. 02 ± 1. 77)‰,(-32. 13 ± 0. 59)‰ to(-27. 67 ± 0. 49)‰,(-27. 58 ± 0. 16)‰ to(-25. 50 ±0. 75)‰,and(-25. 14 ± 0. 93)‰ to(-23. 44 ± 1. 32)‰,respectively. The δ13C value of styrene was(-23. 44 ± 1. 32)‰,which was only detected in the fumes emitted through domestic coal combustion. Additionally,the sample analysis based on data collected from four different functional zones of Taiyuan City revealed the following:① the δ13C values of the atmospheric volatile aromatic compounds in the mixed residential and traffic zone ranged from(-25. 61 ± 2. 20)‰ to(-23. 91 ± 0. 78)‰. Compared with other functional zones,the emissions in this zone were enriched with13 C;and ② the δ13C values measured in the industrial zone ranged from(-29. 15 ± 1. 06)‰ to(-24. 53 ± 1. 07)‰;the emissions in this functional zone were relatively low in13 C compared with other zones. A comparison of the δ13C values of the atmospheric volatile aromatic compounds and emission sources indicated that the main sources of volatile aromatic compounds at the four sampling points in Taiyuan were vehicle exhausts and domestic coal combustion,while the air sampled in the industrial functional zone was heavily affected by the volatilization of solvents.