Phosphate depletion in the western North Atlantic Ocean
Phosphate depletion in the western North Atlantic Ocean
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DOI：
10.1126/science.289.5480.759
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发表时间：
2000-08-04
期刊：
影响因子：
56.9
通讯作者：
Karl, DM
中科院分区：
文献类型：
--
作者：
Wu, JF;Sunda, W;Karl, DM
亚热带马尾藻海的表面沃茨含有0.2至1.0纳摩尔的溶解无机磷酸盐（DIP）浓度，其浓度低到足以导致初级生产的磷控制。该地区的DIP浓度（从北非干旱地区接收大量富含铁的尘埃）比北太平洋的地表浓度低一到两个数量级（风成铁输入量低得多，水柱反硝化作用更大）。这些数据表明，在大西洋严重的相对磷耗尽。我们假设，氮与磷限制初级生产在当今的海洋可能是密切相关的铁供应，通过控制二氮（N-2）固定，铁密集的代谢过程。尽管海洋磷清单可能设定了地质时间尺度上海洋中产生的有机物总量的上限，但在地质时间的任何时刻，由于铁供应持续不足，海洋初级生产力可能低于这一上限。通过控制N-2固定，铁不仅可以控制氮与磷的限制，而且还可以控制碳固定和输出化学计量，从而控制大气二氧化碳的生物封存。
Surface waters of the subtropical Sargasso Sea contain dissolved inorganic phosphate (DIP) concentrations of 0.2 to 1.0 nanomolar, which are sufficiently Low to result in phosphorus control of primary production. The DIP concentrations in this area (which receives high inputs of iron-rich dust from arid regions of North Africa) are one to two orders of magnitude lower than surface Levels in the North Pacific (where eolian iron inputs are much Lower and water column denitrification is much more substantial). These data indicate a severe relative phosphorus depletion in the Atlantic. We hypothesize that nitrogen versus phosphorus Limitation of primary production in the present-day ocean may be closely linked to iron supply through control of dinitrogen (N-2) fixation, an iron-intensive metabolic process. Although the oceanic phosphorus inventory may set the upper Limit for the total amount of organic matter produced in the ocean over geological time scales, at any instant in geological time, oceanic primary production may fall below this Limit because of a persistent insufficient iron supply. By controlling N-2 fixation, iron may control not only nitrogen versus phosphorus Limitation but also carbon fixation and export stoichiometry and hence biological sequestration of atmospheric carbon dioxide.