【摘要】 从天然气中分离、接收氮气,用质谱仪测定δ¹⁵N的方法是天然气地球化学研究的新手段。用该方法测得国内首批天然气的δ¹⁵N数据。测得兰州市区大气的氮同位素组成(¹⁵N/¹⁴N的平均值为0.00368)比Nier（1950）报道的大气的氮同位素组成(¹⁵N/¹⁴N的平均值为0.00361)稍富集¹⁵N。这可能是一种自然现象,也可能是分析方法不同造成的。更多还原

【Abstract】 The method has been developed with which nitrogen is seperated by gas chromatograph and collected in a vacuum system, and isotope ratio of nitrogen are measured by mass spectrometry.The mean value of nitrogen isotope ratio of air in Lanzhou is 0.00368, with a standard deviation 0. 000053 (n= 7) , which is slightly higher than that of 15N/ 14N (0.00361) reported by Nier (1950) .The defference between the two measurements may be either due to analysing methods or may substantially reflects the natural phenomenon. While to the nitrogen Produced by 504 Factory in Lanzhou the mean value of 15N / 14Nis 0.00361, with a standard deviation 0.000050 (n = 5) .This method is an important means for geochemistry of natural gas, and through which the first batch of (δ15 N value of natural gas has been, so far obtained in China.更多还原