Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability
Large-scale distribution of Atlantic nitrogen fixation controlled by iron availability
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DOI：
10.1038/ngeo667
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发表时间：
2009-12-01
影响因子：
18.3
通讯作者：
Woodward, E. Malcolm S.
中科院分区：
文献类型：
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作者：
Moore, C. Mark;Mills, Matthew M.;Woodward, E. Malcolm S.
海洋中固定氮的浓度受固氮和反硝化之间的平衡控制（1-4）。许多因素，包括铁的限制（5-7），可以限制固氮，引入潜在的脱钩氮输入和损失（2，5，8）。这种脱钩可能会严重影响海洋固定氮存量，从而影响海洋碳储存的生物组成部分，进而影响二氧化碳的海气分配（2、5、8、9）。然而，营养物质在多大程度上限制了全球海洋中的固氮作用尚不确定。在这里，我们研究了2005年10月和11月期间沿沿着南北10,000公里样带的大西洋表层水的固氮率和营养盐浓度。我们表明，固氮率显着高于在北大西洋与南大西洋相比。在这两个流域，固氮与溶解铁呈正相关，与溶解磷浓度呈负相关。我们的结论是，流域间的差异，在固氮控制铁供应，而不是磷的可用性。对深层沃茨营养物含量的分析表明，固定氮进入北大西洋深层水。因此，我们的研究支持铁显著影响氮固定的建议（5），并且随后与海洋环流模式的相互作用有助于氮固定和损失的脱钩（2，4，8）。
Oceanic fixed-nitrogen concentrations are controlled by the balance between nitrogen fixation and denitrification(1-4). A number of factors, including iron limitation(5-7), can restrict nitrogen fixation, introducing the potential for decoupling of nitrogen inputs and losses(2,5,8). Such decoupling could significantly affect the oceanic fixed-nitrogen inventory and consequently the biological component of ocean carbon storage and hence air-sea partitioning of carbon dioxide(2,5,8,9). However, the extent to which nutrients limit nitrogen fixation in the global ocean is uncertain. Here, we examined rates of nitrogen fixation and nutrient concentrations in the surfacewaters of the Atlantic Ocean along a north-south 10,000 km transect during October and November 2005. We show that rates of nitrogen fixation were markedly higher in the North Atlantic compared with the South Atlantic Ocean. Across the two basins, nitrogen fixation was positively correlated with dissolved iron and negatively correlated with dissolved phosphorus concentrations. We conclude that inter-basin differences in nitrogen fixation are controlled by iron supply rather than phosphorus availability. Analysis of the nutrient content of deep waters suggests that the fixed nitrogen enters North Atlantic Deep Water. Our study thus supports the suggestion that iron significantly influences nitrogen fixation(5), and that subsequent interactions with ocean circulation patterns contribute to the decoupling of nitrogen fixation and loss(2,4,8).