摘要:
采用气相色谱/燃烧/同位素比值质谱(GC/C/IRMS)技术,通过2,4-二硝基苯肼(DNPH)衍生化方法,初步测定了广州市城区交通主干线大气中甲醛、乙醛和丙酮的碳同位素组成.结果表明,甲醛的δ13C值变化范围为-42.06‰—-33.52‰,乙醛的δ13C值变化范围为-35.84‰—-32.20‰,丙酮的δ13C值变化范围为-30.85‰—-29.50‰;而且,白天相对于夜晚而言,甲醛、乙醛和丙酮的最大碳同位素分馏分别为6.65‰,3.27‰和0.75‰,碳同位素分馏上的差异表明它们在环境大气中不同化学活性上的差异.
Abstract:
Carbon isotopic compositions of atmospheric typical carbonyl compounds(including formaldehyde,acetaldehyde,and acetone)in Guangzhou city were measured by gas chromatography/combustion/isotope ratio mass spectrometry(GC/C/IRMS)through carbonyls via 2,4-dinitrophenylhydrazine derivatizations.Ambient samples were taken above two traffic main lines in Guangzhou.Isotopic data of ambient formaldehyde was found to be in a wide range oF-42.06‰ to-33.52‰.In contrast,δ13C values of ambient acetaldehyde and acetone varied in a small range(-35.84‰ to-32.20‰ and-30.85‰ to-29.50‰,respectively).Furthermore,the ambient data measured in the daytime generally showed heavier values than those measured in the nighttime.Averagely,the isotopic data in the daytime were enriched maximally in δ13C by 6.65‰,3.27‰ and 0.75‰ for ambient formaldehyde,acetaldehyde,and acetone,respectively,suggesting different fractionations during different chemical processes in the atmosphere.
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