Large flux of iron from the Amery Ice Shelf marine ice to Prydz Bay, East Antarctica
Large flux of iron from the Amery Ice Shelf marine ice to Prydz Bay, East Antarctica
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DOI：
10.1002/2016jc011687
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发表时间：
2016-08-01
影响因子：
3.6
通讯作者：
Pedro, J. B.
中科院分区：
文献类型：
--
作者：
Herraiz-Borreguero, L.;Lannuzel, D.;Pedro, J. B.
南极大陆架维持着高水平的海洋初级生产力，通过生物泵的光合作用固定二氧化碳，是全球重要的二氧化碳汇。维持如此高的生产率需要大量的必需微量营养素铁（Fe）的供应，然而，铁传递到这些区域的途径在空间和时间上各不相同。我们的研究是第一次报告一个以前未量化的浓缩生物有效铁源南极表面沃茨。我们假设，铁来自冰下过程被交付到真光沃茨通过吸积（铁存储）和随后的融化（铁释放）的海洋吸积层的冰在该基地的埃默里冰架（AIS）。使用卫星来源的叶绿素a数据，我们表明，由海洋冰层的融化提供的可溶性铁是一个数量级大于所需的铁，以维持每年的大型浮游植物水华在Preniz湾。我们发现的高浓度的铁在AIS海冰和最近的数据，在许多南极洲的冰架的冰架基底融化率的增加，应鼓励进一步研究冰架下的冰川和海洋沉积物的运输和他们的敏感性，目前的变化在基底融化。目前，南极海冰的分布，体积和铁浓度的限制很差。这种不确定性，结合变化的预测速度增加的冰架基底融化，限制了我们的能力，以预测未来的铁供应到南极沿海沃茨。
The Antarctic continental shelf supports a high level of marine primary productivity and is a globally important carbon dioxide (CO2) sink through the photosynthetic fixation of CO2 via the biological pump. Sustaining such high productivity requires a large supply of the essential micronutrient iron (Fe); however, the pathways for Fe delivery to these zones vary spatially and temporally. Our study is the first to report a previously unquantified source of concentrated bioavailable Fe to Antarctic surface waters. We hypothesize that Fe derived from subglacial processes is delivered to euphotic waters through the accretion (Fe storage) and subsequent melting (Fe release) of a marine-accreted layer of ice at the base of the Amery Ice Shelf (AIS). Using satellite-derived Chlorophyll-a data, we show that the soluble Fe supplied by the melting of the marine ice layer is an order of magnitude larger than the required Fe necessary to sustain the large annual phytoplankton bloom in Prydz Bay. Our finding of high concentrations of Fe in AIS marine ice and recent data on increasing rates of ice shelf basal melt in many of Antarctica's ice shelves should encourage further research into glacial and marine sediment transport beneath ice shelves and their sensitivity to current changes in basal melt. Currently, the distribution, volume, and Fe concentration of Antarctic marine ice is poorly constrained. This uncertainty, combined with variable forecasts of increased rates of ice shelf basal melt, limits our ability to predict future Fe supply to Antarctic coastal waters.