The decline and fate of an iron-induced subarctic phytoplankton bloom
The decline and fate of an iron-induced subarctic phytoplankton bloom
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DOI：
10.1038/nature02437
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发表时间：
2004-04-01
期刊：
影响因子：
64.8
通讯作者：
Yoshimura, T
中科院分区：
文献类型：
--
作者：
Boyd, PW;Law, CS;Yoshimura, T
铁供应在高硝酸盐低叶绿素海水中对刺激浮游植物繁殖起关键作用（1-5）。然而，这些藻华所固定的碳的命运，以及它们如何有效地输出到海洋内部，在很大程度上仍然是未知的（1-5）。在这里，我们报道阿拉斯加湾铁刺激硅藻华的衰落和命运。在铁和硅酸耗尽后，藻华在第18天终止，此后混合层颗粒有机碳（POC）浓度在6天内下降。从第21天开始，在深度为50 ~ 125 m的沉积物捕集器中记录到通过下沉硅藻的二氧化硅颗粒出口增加，但POC出口增加直到第24天才明显。混合层POC只有一小部分被捕集器截获，超过一半的混合层POC赤字归因于细菌再矿化和中浮游动物的放牧。硅酸的耗竭和铁增加的POC在永久温跃层以下的低效转移，对过去地质时期铁供应增加时期的生物地球化学解释（6,7）以及提出的增加海洋碳固存的地球工程方案（3,8）都有重大影响。
Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters(1-5). However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown(1-5). Here we report on the decline and fate of an iron-stimulated diatom bloom in the Gulf of Alaska. The bloom terminated on day 18, following the depletion of iron and then silicic acid, after which mixed-layer particulate organic carbon (POC) concentrations declined over six days. Increased particulate silica export via sinking diatoms was recorded in sediment traps at depths between 50 and 125 m from day 21, yet increased POC export was not evident until day 24. Only a small proportion of the mixed-layer POC was intercepted by the traps, with more than half of the mixed-layer POC deficit attributable to bacterial remineralization and mesozooplankton grazing. The depletion of silicic acid and the inefficient transfer of iron-increased POC below the permanent thermocline have major implications both for the biogeochemical interpretation of times of greater iron supply in the geological past(6,7), and also for proposed geo-engineering schemes to increase oceanic carbon sequestration(3,8).