[On-line method for measurement of the carbon isotope ratio of atmospheric methane and its application to atmosphere of Yakela condensed gas field].
An on-line method for measurement of the 13C/12C ratio of methane by a gas chromatography/high-temperature conversion/ isotope ratio mass spectrometry (GC/C/MS) technique was developed. This method is less laborious, more rapid (45 min), of high precision (+/- 0.4 x 10(-3)) and by using a small amount of sample (about 200 mL of atmosphere). Its application to isotopic characterization, and hence methane source identification, was demonstrated by examination of atmosphere sample collected in Yakela condensed gas field, China. The average 13C/12C ratio of atmospheric methane in Yakela field was -45.0 x 10(-3) heavier by 1.2 x 10(-3) -2.0 x 10(-3) than the global average. This is caused by seepage and diffusing of methane from Yakela condensed gas reservoir. The concentrations of atmospheric methane in daytimes are found to be lower than those in nighttimes, and the corresponding 13C/12C ratios in daytimes are lighter compared to those in nighttimes, a phenomena probably caused by the fact that a small part of methane from Yakela condensate reservoir is consumed in soil's surface under sunlight.
Tang
Jun-Hong
JH
Department of Environmental Sciences and Engineering, Hangzhou Dianzi University, Hangzhou 310018, China. Tang_jhjh@tom.com
Bao
Zheng-Yu
ZY
Xiang
Wu
W
Qiao
Sheng-Ying
SY
Li
Bing
B
D000388:Air / Q000032:analysis; D001272:Atmosphere / Q000032:analysis*; D002247:Carbon Isotopes / Q000032:analysis*; D002623:Chemistry Techniques, Analytical / Q000379:methods; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D008697:Methane / Q000032:analysis*
D002247:Carbon Isotopes; D008697:Methane