Boyd P W, Watson A J, Law C S, Abraham E R, Trull T, Murdoch R, Bakker D C, Bowie A R, Buesseler K O, Chang H, Charette M, Croot P, Downing K, Frew R, Gall M, Hadfield M, Hall J, Harvey M, Jameson G, LaRoche J, Liddicoat M, Ling R, Maldonado M T, McKay R M, Nodder S, Pickmere S, Pridmore R, Rintoul S, Safi K, Sutton P, Strzepek R, Tanneberger K, Turner S, Waite A, Zeldis J
National Institute of Water and Atmosphere, Centre for Chemical and Physical Oceanography, Department of Chemistry, University of Otago, Dunedin, New Zealand.
Nature. 2000 Oct 12;407(6805):695-702. doi: 10.1038/35037500.
Changes in iron supply to oceanic plankton are thought to have a significant effect on concentrations of atmospheric carbon dioxide by altering rates of carbon sequestration, a theory known as the 'iron hypothesis'. For this reason, it is important to understand the response of pelagic biota to increased iron supply. Here we report the results of a mesoscale iron fertilization experiment in the polar Southern Ocean, where the potential to sequester iron-elevated algal carbon is probably greatest. Increased iron supply led to elevated phytoplankton biomass and rates of photosynthesis in surface waters, causing a large drawdown of carbon dioxide and macronutrients, and elevated dimethyl sulphide levels after 13 days. This drawdown was mostly due to the proliferation of diatom stocks. But downward export of biogenic carbon was not increased. Moreover, satellite observations of this massive bloom 30 days later, suggest that a sufficient proportion of the added iron was retained in surface waters. Our findings demonstrate that iron supply controls phytoplankton growth and community composition during summer in these polar Southern Ocean waters, but the fate of algal carbon remains unknown and depends on the interplay between the processes controlling export, remineralisation and timescales of water mass subduction.
海洋浮游生物的铁供应变化被认为会通过改变碳固存速率对大气二氧化碳浓度产生重大影响，这一理论被称为“铁假说”。因此，了解远洋生物群对铁供应增加的反应很重要。在此，我们报告了在南极海洋进行的中尺度铁施肥实验的结果，在那里，固存铁含量升高的藻类碳的潜力可能最大。铁供应增加导致表层水体中浮游植物生物量增加和光合作用速率提高，造成二氧化碳和大量营养素大幅减少，以及13天后二甲基硫水平升高。这种减少主要是由于硅藻种群的增殖。但生物源碳的向下输出并未增加。此外，30天后对这次大规模水华的卫星观测表明，添加的铁有足够比例保留在表层水体中。我们的研究结果表明，在南极海洋这些水域的夏季，铁供应控制着浮游植物的生长和群落组成，但藻类碳的归宿仍然未知，并且取决于控制输出、再矿化和水体俯冲时间尺度的过程之间的相互作用。
