Extending records of the isotopic composition of atmospheric N2O back to 1800 A.D. from air trapped in snow at the South Pole and the Greenland Ice Sheet Project II ice core
Extending records of the isotopic composition of atmospheric N2O back to 1800 A.D. from air trapped in snow at the South Pole and the Greenland Ice Sheet Project II ice core
复制标题
将南极和格陵兰冰盖项目 II 冰芯中困在空气中的大气氧化亚氮同位素组成的记录追溯到公元 1800 年
DOI：
10.1029/2002gb001911
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发表时间：
2002
影响因子：
5.2
通讯作者：
S. Toyoda
中科院分区：
文献类型：
--
作者：
T. Sowers;A. Rodebaugh;N. Yoshida;S. Toyoda
N_2O同位素组成变化的历史记录对于更好地理解大气N_2O的地球化学循环具有重要意义。在这里，我们结合联合收割机的测量被困气体在格陵兰冰盖项目II（GISP II）南极冰芯和积雪间隙空气中N_2O的同位素组成，重建了1785年以来的大气N_2O同位素记录。1785 ~ 1819年6次冰气年龄测量结果表明，大气N_2O的δ ~（15）N和δ ~（18）O分别为10.1 ± 0.01和10.1 ± 0.01 0.6和47.4 ± 1.0‰。这些值比本研究中测量的当前值高1.9和2.9‰。建立了一个简单的两箱大气模型，以模拟过去250年来大气N2 O的各种源和汇。模型结果表明，1995年人为N2 O排放总量在4.2和5.7 Tg N yr−1之间。冰芯和箱模型的结果进行了比较，δ 15 N和δ 18 O测量的空气中被困在南极积雪跨越世纪。结果表明，近世纪以来，大气N_2O的δ 15 N和δ 18 O分别下降了1.7和0.9‰。这些数据支持以前的预测，减少大气同位素比，这是一个30%的N2 O排放总量增加，主要与农业活动有关。
A historical record of changes in the N2O isotope composition is important for a better understanding of the biogeochemical cycles involving atmospheric N2O. Here we combine measurements of trapped gases in the Greenland Ice Sheet Project II (GISP II) ice core and the interstitial air from the snowpack at the South Pole to reconstruct atmospheric N2O isotope records back to 1785 A.D. Results from six measurements of ice with gas ages between 1785 and 1819 A.D. indicate that the δ15N and δ18O of atmospheric N2O was 10.1 ± 0.6 and 47.4 ± 1.0‰, respectively. These values are 1.9 and 2.9‰ higher than present‐day values as measured in this study. A simple two‐box atmospheric model was constructed to simulate the various sources and sinks of atmospheric N2O over the last 250 years. Model results suggest that the total anthropogenic N2O emissions in 1995 were between 4.2 and 5.7 Tg N yr−1. The ice core and box model results were compared to δ15N and δ18O measurements of air trapped in the snowpack at South Pole spanning the 20th century. Our results suggest that δ15N and δ18O of atmospheric N2O have dropped by 1.7 and 0.9‰, respectively, during the last century. These data support previous predictions of decreasing atmospheric isotope ratios that are related to a ∼30% increase in total N2O emissions which are primarily related to agricultural activities.