Productivity in the Southern Oceans is iron-limited, and the supply of iron dissolved from aeolian dust is believed to be the main source from outside the marine reservoir. Glacial sediment sources of iron have rarely been considered, as the iron has been assumed to be inert and non-bioavailable. This study demonstrates the presence of potentially bioavailable Fe as ferrihydrite and goethite in nanoparticulate clusters, in sediments collected from icebergs in the Southern Ocean and glaciers on the Antarctic landmass. Nanoparticles in ice can be transported by icebergs away from coastal regions in the Southern Ocean, enabling melting to release bioavailable Fe to the open ocean. The abundance of nanoparticulate iron has been measured by an ascorbate extraction. This data indicates that the fluxes of bioavailable iron supplied to the Southern Ocean from aeolian dust (0.01–0.13 Tg yr-1) and icebergs (0.06–0.12 Tg yr-1) are comparable. Increases in iceberg production thus have the capacity to increase productivity and this newly identified negative feedback may help to mitigate fossil fuel emissions.
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机译：南部海洋的生产力受到铁的限制，从风尘中溶解的铁的供应被认为是海洋水库外部的主要来源。由于铁被认为是惰性且不可生物利用的，因此很少考虑铁的冰川沉积物来源。这项研究表明，在从南大洋冰山和南极大陆冰川收集的沉积物中，纳米颗粒团簇中存在潜在的生物利用铁，水铁矿和针铁矿。冰山中的纳米颗粒可以通过冰山从南大洋的沿海地区运走，从而使其融化，从而将可利用的铁释放到大洋中。纳米颗粒铁的丰度已通过抗坏血酸提取进行了测量。该数据表明，从风尘（0.01–0.13 Tg yr -1 ）和冰山（0.06-0.12 Tg yr -1 ）向南大洋供应的生物利用铁通量）具有可比性。因此，冰山产量的增加有提高生产力的能力，这种新发现的负面反馈可能有助于减轻化石燃料的排放。
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