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High-Precision Measurement of N2O Concentration in Ice Cores
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2018-01-05 00:00:00 , DOI: 10.1021/acs.est.7b05250
Yeongjun Ryu 1 , Jinho Ahn 1 , Ji-Woong Yang 1
Affiliation  

Atmospheric nitrous oxide (N2O) is a greenhouse gas and ozone-depleting substance whose emissions are substantially perturbed by current human activities. Although air trapped in polar ice cores can provide direct information about N2O evolution, analytical precision was not previously sufficient for high temporal resolution studies. In this work, we present a highly improved analytical technique with which to study N2O concentrations in ancient-air-trapped ice cores. We adopt a melt–refreezing method to extract air and use a gas chromatography–electron capture detector (GC–ECD) to determine N2O concentrations. The GC conditions are optimized to improve the sensitivity for detecting N2O. Retrapped N2O in ice during the extraction procedure is precisely analyzed and corrected. We confirmed our results using data from the Styx Glacier ice core in Antarctica by comparing them with the results of a dry-extraction method. The precision estimated from the pooled standard deviation of replicated measurements of the Styx ice core was 1.5 ppb for ∼20 g of ice, a smaller sample of ice than was used in previous studies, showing a significant improvement in precision. Our preliminary results from the Styx Glacier ice core samples have the potential to define small N2O variations (a few parts per billion) at centennial time scales.

中文翻译:

高精度测量冰芯中N 2 O的浓度

大气中的一氧化二氮(N 2 O)是一种温室气体和消耗臭氧层的物质,其排放基本上受到当前人类活动的干扰。尽管截留在极地冰芯中的空气可以提供有关N 2 O释放的直接信息,但分析精度以前不足以用于高时间分辨率研究。在这项工作中,我们提出了一种经过高度改进的分析技术,可用于研究古代被困在空气中的冰芯中的N 2 O浓度。我们采用熔融-再冷冻方法提取空气,并使用气相色谱-电子捕获检测器(GC-ECD)确定N 2 O的浓度。优化了GC条件以提高检测N 2 O的灵敏度。萃取过程中冰中的2 O会被精确分析和校正。我们通过使用南极的Styx冰川冰芯的数据与干法提取的结果进行比较来证实我们的结果。根据Styx冰芯重复测量的合并标准偏差估计的精度,对于约20 g的冰,其精度为1.5 ppb,比以前的研究中使用的冰样小,显示出精度的显着提高。我们从Styx冰川冰芯样本获得的初步结果有可能在百年尺度上定义小的N 2 O变化(十亿分之几)。
更新日期:2018-01-05
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