Isotopic Character of Nitrous Oxide Emitted from Streams
Isotopic Character of Nitrous Oxide Emitted from Streams
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DOI：
10.1021/es104116a
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发表时间：
2011-06-01
影响因子：
11.4
通讯作者：
Dillon, Peter J.
中科院分区：
文献类型：
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作者：
Baulch, Helen M.;Schiff, Sherry L.;Dillon, Peter J.
全球模型表明，受农业影响的河流和溪流可能是温室气体一氧化二氮 (N2O) 的重要来源。然而，N2O 预算存在很大的不确定性。同位素表征可用于帮助限制 N2O 预算。我们首次公布了低 (2-4) 阶流中释放的 N2O 同位素特征的测量结果。 N2O 的同位素特征随季节、溪流和昼夜变化而变化。按年计算，排放的 N2O 的 Delta O-18（千分之 47.4 至 +51.4；相对于 VSMOW）高于先前报告的较大河流，但排放的 N2O 的 Delta N-15（溪流中的 千分之 -16.2 至 +2.4；相对于大气 N-2）与过去的研究相似。每年，所有溪流排放的 N2O 的 Delta N-15 均低于对流层 N2O。鉴于这些溪流的硝酸盐浓度升高，这与 N2O 通量增加有关，这支持了这样的假设：溪流有助于对流层中 N-15 耗尽的 N2O 的积累。
Global models have indicated agriculturally impacted rivers and streams may be important sources of the greenhouse gas nitrous oxide (N2O). However, there is significant uncertainty in N2O budgets. Isotopic characterization can be used to help constrain N2O budgets. We present the first published measurements of the isotopic character of N2O emitted from low (2-4) order streams. Isotopic character of N2O varied seasonally, among streams, and over diel periods. On an annual basis, delta O-18 of emitted N2O (+47.4 to +51.4 parts per thousand; relative to VSMOW) was higher than previously reported for larger rivers, but delta N-15 of emitted N2O (-16.2 to +2.4 parts per thousand among streams; relative to atmospheric N-2) was similar to that of past studies. On an annual basis, all streams emitted N2O with lower delta N-15 than tropospheric N2O. Given these streams have elevated nitrate concentrations which are associated with enhanced N2O fluxes, this supports the hypothesis that streams are contributing to the accumulation of N-15-depleted N2O in the troposphere.