兰州市和太原市环境空气中NMHCs的碳同位素组成特征

Carbon Isotopic Composition Characteristic of Nonmethane Hydrocarbons in Atmosphere of Lanzhou and Taiyuan City

研究了兰州市和太原市环境空气中非甲烷烃(NMHCs)的污染状况及来源。利用Tenax-TA吸附管采样,热解析-色谱-同位素质谱联用仪(TD-GC-IRMS)测定了两个城市夏季不同功能区环境空气中NMHCs的稳定碳同位素组成。得出,兰州市和太原市居民区苯的δ(13C)分别为-26.4‰和-25.0‰;正烷烃的δ(13C)分别为-33.9‰^-26.1‰,-32.8‰^-27.4‰;两市交通枢纽区环境空气中检测出的C4—C7之间的NMHCs化合物相同,δ(13C)相差不大,兰州市为-30.8‰^-25.6‰,太原市为-31.0‰^-26.4‰。结果表明,两市交通枢纽区苯主要来源于汽车尾气和油类挥发,工业区石化行业类主要排放的NMHCs污染物为苯和烷烃类化合物,电厂等大型企业主要排放异丁烯、顺-2-戊烯等。控制汽车尾气、油类挥发、工业排放是降低环境空气中NMHCs污染的关键。

Sampled by Tenax-TA adsorption tube, the stable carbon isotopic composition of non-methane hydrocarbons （NMHCs） in summer atmosphere in different functional districts in Lanzhou and Taiyuan city was determined by Thermal Desorption-Gas Chromatography-Isotope Ratio Mass Chromatography. The results indicate that the δ^13C values of benzene and n-alkanes are -26. 4‰, -33. 9‰- -26. 1‰ and 25.0‰, 32.8‰- -27.4‰ respectively in residential area in Lanzhou and Taiyuan city respectively; the sorts of NMHCs compounds determined in transport hubs in the two cities are the same and the δ^13C values are -30.8‰- -25.6‰ and -31.0‰- -26.4‰, respectively. The results furthermore indicate that benzene are mainly from vehicle exhaust and fuel volatile in transport hub in the two cities; the main components of NMHCs are benzene and alkanes in petrochemical industry in industrial estate, while large enterprise such as power plants mainly emits isobutene and cis-2-petene etc. Controlling vehicle exhaust, fuel volatile and industry emissions is the key to reduce a mospheric NMHCs pollution.