摘要:
本文讨论了大气中N2O的GC-ECD测定方法.对影响色谱分离效能的动力学因素(操作变置):载气流速、检测器和分离柱的温度进行了选择研究.方法有高的灵敏度和好的选择性,检测极限达到2.48×10-11g·ml-1.由于采用了两个样品连续进样的程序,使样品的分析时间节省了约30%.本法不仅适用测量大气中N2O,也能同时测量CO2.应用本法对北京大学周围地区和河北省的一些典型环境中N2O的浓度进行了测量,结果表明:(1)北京大学校园地区(采暖期)浓度均值为349ppbv(s.d=3ppbv,n=40),(2)有机堆肥场均值高达362ppbv(s.d=7ppbv,n=4),(3)稻田的均值为352ppbv(s.d=10ppbv,n=10),(4)林-农生态系统均值为345ppbv(s.d=18ppbv,n=192).比较这些数据可看出,有机堆肥是N2O较强的排放源,稻田和燃烧过程也是大气N2O的源.
Abstract:
This paper disscussed the method of electron capture gas chromatogra-phy(GC-ECD)for measurement of N2O in air. We have researched following operating parameters that will affect separation effect of chromatography: flow rate of carrier gas, temperatures of detector and column. This method had high sensitivity and fine selectivity,detection limit reach up to 2.48�10-11g·ml-1. Analytical time of samples was saved about 30% when continue procedure of injection for two samples had been adopted. Not only can this method determine the N2O in air, but also it can determine the CO2.During March to July, 1992,the ground level N2O concentrations of some typical environments have been determined in and around Peking University and Hebei province;(l)compus area of Peking University(heating days), mean was 349ppbv(s.d=3ppbv, n=40);(2)field of organic piles, mean was 362ppbv(s.d=7ppbv, n=4);(3)rice field, mean was 352 ppbv(s.d=10ppbv, n=10);(4)wood crop ecosystem, mean was 345ppbv(s.d=18ppbv, n=192). Comparing with these data, following results could be shown; the organic piles had stronger source activity; rice field and combustion process were the sources of air N2O.
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