Global Nitrous Oxide Production Determined by Oxygen Sensitivity of Nitrification and Denitrification
Global Nitrous Oxide Production Determined by Oxygen Sensitivity of Nitrification and Denitrification
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利用硝化和反硝化的氧敏感性确定全球氧化亚氮的产量
DOI：
10.1029/2018gb005887
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发表时间：
2018-12-01
影响因子：
5.2
通讯作者：
Ward, Bess B.
中科院分区：
文献类型：
--
作者：
Ji, Qixing;Buitenhuis, Erik;Ward, Bess B.
据估计，海洋贡献了大气中一氧化二氮（N2O）全球通量的近20%，这是一种重要的温室气体和臭氧消耗剂。海洋氧最小带对这一通量的贡献不成比例。为了进一步了解硝化和反硝化的分配及其对海洋N2O通量的环境控制，我们报道了在热带太平洋东部用N-15示踪剂直接测量的氧浓度与硝化和反硝化产生N2O速率之间的新关系。最高的N2O产率发生在缺氧-缺氧界面附近，那里有很强的N2O向大气流出的潜力。最小氧区N2O的主要来源为硝态氮还原，其还原速率比铵态氮氧化速率高1 ~ 2个数量级。氧气的存在显著抑制了硝化和反硝化过程中N2O的产生。这些实验数据为多组分全球海洋生物地球化学模型提供了新的约束条件，该模型得出每年海洋N2O流出量为1.7-4.4Tg-N（中位数为2.8Tg-N, 1 Tg=10(12)g），其中反硝化作用贡献了20%的海洋通量。因此，反硝化应被视为海洋环境中N2O的净生产途径。
The ocean is estimated to contribute up to similar to 20% of global fluxes of atmospheric nitrous oxide (N2O), an important greenhouse gas and ozone depletion agent. Marine oxygen minimum zones contribute disproportionately to this flux. To further understand the partition of nitrification and denitrification and their environmental controls on marine N2O fluxes, we report new relationships between oxygen concentration and rates of N2O production from nitrification and denitrification directly measured with N-15 tracers in the Eastern Tropical Pacific. Highest N2O production rates occurred near the oxic-anoxic interface, where there is strong potential for N2O efflux to the atmosphere. The dominant N2O source in oxygen minimum zones was nitrate reduction, the rates of which were 1 to 2 orders of magnitude higher than those of ammonium oxidation. The presence of oxygen significantly inhibited the production of N2O from both nitrification and denitrification. These experimental data provide new constraints to a multicomponent global ocean biogeochemical model, which yielded annual oceanic N2O efflux of 1.7-4.4Tg-N (median 2.8Tg-N, 1 Tg=10(12)g), with denitrification contributing 20% to the oceanic flux. Thus, denitrification should be viewed as a net N2O production pathway in the marine environment.