High-resolution profiles and nitrogen isotope tracing reveal a dominant source of nitrous oxide and multiple pathways of nitrogen gas formation in the central Arabian Sea
High-resolution profiles and nitrogen isotope tracing reveal a dominant source of nitrous oxide and multiple pathways of nitrogen gas formation in the central Arabian Sea
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DOI：
10.4319/lo.2007.52.1.0156
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发表时间：
2007-01-01
影响因子：
4.5
通讯作者：
Trimmer, Mark
中科院分区：
文献类型：
--
作者：
Nicholls, Joanna Claire;Davies, Christian Andrew;Trimmer, Mark
阿拉伯海的最小含氧区（OMZ）是一氧化二氮（N2 O）的重要来源，但N2 O产生的代谢机制尚不清楚。高分辨率的配置文件确定了N2 O和NO2-在顶部500在水柱的波峰和波谷。N2 O的第一个峰不在氧跃层中，而是在氧-亚氧界面处较深。用一系列N-15孵育（（NO3-）-N-15、（NO2-）-N-15、（NH 4+）-N-15）靶向峰和谷，以鉴定N2 O和N-2形成的途径。（NO2-）-N-15在各深度均产生N-15-N2 O，其产生量与NO2-库成二项分布。在（NO3-）-N-15中，N-15不呈二项分布。NO3-在还原成N2 O之前首先还原成NO2-，并且NO2- -> N2 O是负责N2 O产生的主要代谢。在OMZ顶部，（NH ~（4+）-N ~（15））产生的N_2O占（NO ~（2-）-N ~（15））产生的N_2O的2-5%。此外，（N2 O）-N-45的生产，但没有（N2 O）-N-46，在某些深度与（NH 4+）-N-15，提出了一个新的来源类似于亚硝化单胞菌属。在O-2限制下。与N2 O不同，N-2与（NO2-）-N-15或（NO3-）-N-15的产生不是二项式分布的，因此不完全来自与N2 O相同的来源。虽然指示的替代N2源反硝化，标记N2与（NH 4+）-N-15的显着生产的缺乏折扣厌氧氨氧化（anammox），因为我们理解it. Dissolved有机氮或硝酸盐/亚硝酸盐还原为铵被认为是N-2生产的额外的N源。
The oxygen minimum zone (OMZ) of the Arabian Sea is a significant source of nitrous oxide (N2O), yet the metabolism responsible for N2O production is unclear. High-resolution profiles identified peaks and troughs of N2O and NO2- in the top 500 in of the water column. The first peak in N2O was not in the oxycline, but deeper at the oxic-suboxic interface. Peaks and troughs were targeted with a suite of N-15 incubations ((NO3-)-N-15, (NO2-)-N-15, (NH4+)-N-15) to identify pathways of N2O and N-2 formation. With (NO2-)-N-15, N-15-N2O was produced at all depths with a binomial distribution with respect to the NO2- pool. With (NO3-)-N-15, the N-15 was not binomially distributed. NO3- is first reduced to NO2- before reduction to N2O, and NO2- -> N2O is the dominant metabolism responsible for N2O production. The N2O produced from (NH4+)-N-15 represented 2-5% of that from (NO2-)-N-15 at the top of the OMZ. In addition, the production of (N2O)-N-45, but no (N2O)-N-46, at some depths with (NH4+)-N-15, suggested a novel source akin to Nitrosomonas spp. under O-2 limitation. Unlike N2O, the production of N-2 with (NO2-)-N-15 or (NO3-)-N-15 was not binomially distributed and therefore was not entirely derived from the same source as N2O. Although indicative of an alternative N2 source to denitrification, the lack of significant production of labeled N2 with (NH4+)-N-15 discounts anaerobic ammonium oxidation (anammox), as we understand it. Dissolved organic nitrogen or nitrate/nitrite reduction to ammonium are suggested as the additional sources of N in N-2 production.