Boyd Philip W, Law Cliff S, Wong C S, Nojiri Yukihiro, Tsuda Atsushi, Levasseur Maurice, Takeda Shigenobu, Rivkin Richard, Harrison Paul J, Strzepek Robert, Gower Jim, McKay Mike, Abraham Edward, Arychuk Mike, Barwell-Clarke Janet, Crawford William, Crawford David, Hale Michelle, Harada Koh, Johnson Keith, Kiyosawa Hiroshi, Kudo Isao, Marchetti Adrian, Miller William, Needoba Joe, Nishioka Jun, Ogawa Hiroshi, Page John, Robert Marie, Saito Hiroaki, Sastri Akash, Sherry Nelson, Soutar Tim, Sutherland Nes, Taira Yosuke, Whitney Frank, Wong Shau-King Emmy, Yoshimura Takeshi
NIWA Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, PO Box 56, Dunedin, 9003, New Zealand.
Nature. 2004 Apr 1;428(6982):549-53. doi: 10.1038/nature02437.
Iron supply has a key role in stimulating phytoplankton blooms in high-nitrate low-chlorophyll oceanic waters. However, the fate of the carbon fixed by these blooms, and how efficiently it is exported into the ocean's interior, remains largely unknown. 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, and also for proposed geo-engineering schemes to increase oceanic carbon sequestration.
铁的供应在刺激高硝酸盐低叶绿素海洋水域中的浮游植物大量繁殖方面起着关键作用。然而，这些水华所固定的碳的去向，以及其被输送到海洋内部的效率如何，在很大程度上仍然未知。在此，我们报告了阿拉斯加湾一次受铁刺激的硅藻水华的衰退和去向。在第18天，随着铁然后是硅酸的耗尽，水华终止，此后混合层颗粒有机碳（POC）浓度在六天内下降。从第21天起，在50至125米深度的沉积物捕集器中记录到通过下沉硅藻增加的颗粒硅输出，但增加的POC输出直到第24天才明显。捕集器仅拦截了混合层POC的一小部分，混合层POC亏缺的一半以上归因于细菌再矿化和中型浮游动物的摄食。硅酸的耗尽以及铁增加的POC在永久温跃层以下的低效转移，对于地质历史上铁供应增加时期的生物地球化学解释以及拟议的增加海洋碳固存的地球工程方案都具有重要意义。
