Effect of natural iron fertilization on carbon sequestration in the Southern Ocean
Effect of natural iron fertilization on carbon sequestration in the Southern Ocean
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DOI：
10.1038/nature05700
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发表时间：
2007-04-26
期刊：
影响因子：
64.8
通讯作者：
Wagener, Thibaut
中科院分区：
文献类型：
--
作者：
Blain, Stephane;Queguiner, Bernard;Wagener, Thibaut
铁的可获得性限制了初级生产力和大面积海洋的相关碳吸收。因此，铁在碳循环中起着重要作用，其向海洋表面供应的变化可能对冰川-间冰期循环中大气二氧化碳浓度产生重大影响（1-5）。迄今为止，铁在碳循环中的作用主要是通过短期铁添加实验来评估的（6，7）。然而，使用这种方法很难可靠地评估向海洋内部输出的碳的数量，而且观测时间短，无法将结果外推到更长的时间尺度（8）。在这里，我们报告的观察浮游植物水华引起的自然铁施肥-一种方法，提供了机会，克服一些短期实验的局限性。我们发现，在南大洋凯尔盖朗高原的大型浮游植物水华的持续供应的铁和主要营养物质的表面沃茨富铁的深水以下。施肥的效率，定义为碳输出与铁供应量的比率，至少比之前通过铁添加实验诱导的短期开花估计高出10倍。这一结果揭示了铁和常量营养素长期施肥对碳固存的影响，表明铁供应的变化-正如在一些古气候（9，10）和未来气候变化情景（11）中所引用的那样-可能对大气二氧化碳浓度产生比以前认为的更显著的影响。
The availability of iron limits primary productivity and the associated uptake of carbon over large areas of the ocean. Iron thus plays an important role in the carbon cycle, and changes in its supply to the surface ocean may have had a significant effect on atmospheric carbon dioxide concentrations over glacial - interglacial cycles(1-5). To date, the role of iron in carbon cycling has largely been assessed using short-term iron-addition experiments(6,7). It is difficult, however, to reliably assess the magnitude of carbon export to the ocean interior using such methods, and the short observational periods preclude extrapolation of the results to longer timescales(8). Here we report observations of a phytoplankton bloom induced by natural iron fertilization - an approach that offers the opportunity to overcome some of the limitations of short-term experiments. We found that a large phytoplankton bloom over the Kerguelen plateau in the Southern Ocean was sustained by the supply of iron and major nutrients to surface waters from iron-rich deep water below. The efficiency of fertilization, defined as the ratio of the carbon export to the amount of iron supplied, was at least ten times higher than previous estimates from short-term blooms induced by iron-addition experiments(7). This result sheds new light on the effect of long-term fertilization by iron and macronutrients on carbon sequestration, suggesting that changes in iron supply from below - as invoked in some palaeoclimatic(9,10) and future climate change scenarios(11) - may have a more significant effect on atmospheric carbon dioxide concentrations than previously thought.