Isotopic Character of Nitrous Oxide Emitted from Streams

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• 作者：Helen M. Baulch ; Sherry L. Schiff ; Simon J. Thuss ; Peter J. Dillon
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：June 1, 2011
• 年：2011
• 卷：45
• 期：11
• 页码：4682-4688
• 全文大小：846K
• 年卷期：v.45,no.11(June 1, 2011)
• ISSN：1520-5851

文摘

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鈥?) order streams. Isotopic character of N₂O varied seasonally, among streams, and over diel periods. On an annual basis, 未¹⁸O of emitted N₂O (+47.4 to +51.4鈥? relative to VSMOW) was higher than previously reported for larger rivers, but 未¹⁵N of emitted N₂O (鈭?6.2 to +2.4鈥?among streams; relative to atmospheric N₂) was similar to that of past studies. On an annual basis, all streams emitted N₂O with lower 未¹⁵N 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 ¹⁵N-depleted N₂O in the troposphere.