Antarctic ice sheet fertilises the Southern Ocean
Antarctic ice sheet fertilises the Southern Ocean
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DOI：
10.5194/bg-11-2635-2014
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发表时间：
2014-01-01
期刊：
影响因子：
4.9
通讯作者：
Raiswell, R.
中科院分区：
文献类型：
--
作者：
Death, R.;Wadham, J. L.;Raiswell, R.
南大洋（SO）海洋初级生产力（PP）受到地表水铁含量的强烈影响，这被认为在冰期/间冰期时间尺度上对大气CO2浓度具有重要控制作用。与南极冰盖接壤的区域显示出高PP和季节性浮游生物大量繁殖，以响应光和铁可用性的变化。铁刺激sopp升高的来源仍有争议。已确定的贡献者包括灰尘、沿海沉积物/上升流、冰山和海冰。从冰缘流出的冰下融水是最近的一种说法，它是由冰盖下强烈的铁循环引起的。冰山和冰下融水可能为SO提供大量的生物可利用铁，在本研究中估计为0.07-0.2 Tg yr（-1）。在这里，我们应用麻省理工学院的全球海洋模型（Follows等人，2007）来确定这种水平的冰盖铁输出对SO PP的潜在影响。冰盖铁输出使模拟的SO PP提高了40%，并为近海岸地区季节性非常高的PP原位测量提供了一个合理的解释。这些结果表明，南极径流和冰山的输出可能对SO PP有重要影响，并应纳入未来的生物地球化学模拟中。
Southern Ocean (SO) marine primary productivity (PP) is strongly influenced by the availability of iron in surface waters, which is thought to exert a significant control upon atmospheric CO2 concentrations on glacial/interglacial timescales. The zone bordering the Antarctic Ice Sheet exhibits high PP and seasonal plankton blooms in response to light and variations in iron availability. The sources of iron stimulating elevated SO PP are in debate. Established contributors include dust, coastal sediments/upwelling, icebergs and sea ice. Subglacial meltwater exported at the ice margin is a more recent suggestion, arising from intense iron cycling beneath the ice sheet. Icebergs and subglacial meltwater may supply a large amount of bioavailable iron to the SO, estimated in this study at 0.07-0.2 Tg yr(-1). Here we apply the MIT global ocean model (Follows et al., 2007) to determine the potential impact of this level of iron export from the ice sheet upon SO PP. The export of iron from the ice sheet raises modelled SO PP by up to 40 %, and provides one plausible explanation for seasonally very high in situ measurements of PP in the near-coastal zone. The impact on SO PP is greatest in coastal regions, which are also areas of high measured marine PP. These results suggest that the export of Antarctic runoff and icebergs may have an important impact on SO PP and should be included in future biogeochemical modelling.