Extensive hydrogen supersaturations in the western South Atlantic Ocean suggest substantial underestimation of nitrogen fixation
Extensive hydrogen supersaturations in the western South Atlantic Ocean suggest substantial underestimation of nitrogen fixation
复制标题
南大西洋西部广泛的氢过饱和表明固氮作用被大大低估
DOI：
10.1002/2014jc010017
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发表时间：
2014
影响因子：
--
通讯作者：
C. Somes
中科院分区：
文献类型：
--
作者：
R. Moore;M. Kienast;M. Fraser;J. Cullen;C. Deutsch;S. Dutkiewicz;M. Follows;C. Somes
氮循环是地球生物地球化学的基础。然而，量化的主要不确定性仍然存在，特别是关于全球海洋固氮率。氢是在固氮过程中产生的，如果重氮营养体有净释放，氢将在地表水中过饱和。因此，对氢过饱和度的海洋调查有可能说明固氮的时空分布，并指导更繁琐但定量的测量方法。在这里，我们展示了沿经向10,000公里穿越大西洋的巡航轨道的地表水氢过饱和度的高分辨率测量的第一个样条。我们将测量的饱和度与已发表的固氮率测量值以及模型推导值进行比较。如果过量氢的主要来源是固氮，并且其氢释放比与Trichodesmium相似，那么我们的氢测量结果将指向北大西洋和南大西洋相似的固氮率，这与模拟的固氮率大致一致，但与测量的固氮率不一致，南方的固氮率较低。可能的解释包括新发现的重氮营养体的大量固氮作用，特别是任何与Trichodesmium相似或超过该比率的氢释放率；赤道以南固氮取样不足与过度关注木霉有关；固氮技术在方法上的缺陷导致了相对于单细胞形式的重氮营养体的偏见。或者，我们的数据受到未知氢源的影响，该源在巡航轨道的南半部比北半部更大。
The nitrogen cycle is fundamental to Earth's biogeochemistry. Yet major uncertainties of quantification remain, particularly regarding the global oceanic nitrogen fixation rate. Hydrogen is produced during nitrogen fixation and will become supersaturated in surface waters if there is net release from diazotrophs. Ocean surveys of hydrogen supersaturation thus have the potential to illustrate the spatial and temporal distribution of nitrogen fixation, and to guide the far more onerous but quantitative methods for measuring it. Here we present the first transect of high resolution measurements of hydrogen supersaturations in surface waters along a meridional 10,000 km cruise track through the Atlantic. We compare measured saturations with published measurements of nitrogen fixation rates and also with model-derived values. If the primary source of excess hydrogen is nitrogen fixation and has a hydrogen release ratio similar to Trichodesmium, our hydrogen measurements would point to similar rates of fixation in the North and South Atlantic, roughly consistent with modelled fixation rates but not with measured rates, which are lower in the south. Possible explanations would include any substantial nitrogen fixation by newly discovered diazotrophs, particularly any having a hydrogen release ratio similar to or exceeding that of Trichodesmium; under-sampling of nitrogen fixation south of the equator related to excessive focus on Trichodesmium; and methodological shortcomings of nitrogen fixation techniques that cause a bias towards colonial diazotrophs relative to unicellular forms. Alternatively our data are affected by an unknown hydrogen source that is greater in the southern half of the cruise track than the northern.
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影响因子：
64.8
作者：
Grosskopf, Tobias;Mohr, Wiebke;LaRoche, Julie
通讯作者：
LaRoche, Julie
影响因子：
18.3
作者：
Moore, C. Mark;Mills, Matthew M.;Woodward, E. Malcolm S.
通讯作者：
Woodward, E. Malcolm S.
DOI：
10.1073/pnas.0400664101
发表时间：
2004-05-25
影响因子：
11.1
作者：
Yang, KC;Metcalf, WW
通讯作者：
Metcalf, WW
影响因子：
5.2
作者：
Dutkiewicz, S.;Ward, B. A.;Follows, M. J.
通讯作者：
Follows, M. J.
影响因子：
11.4
作者：
Luo, Y. -W.;Doney, S. C.;Zehr, J. P.
通讯作者：
Zehr, J. P.