Glacial fjords in Greenland show high productivity owing to the runoff of meltwater from the glaciers. Macronutrient dynamics (of nitrate, phosphate, and silicate) associated with subglacial discharge plumes in front of marine‐terminating glaciers are widely cited as important drivers of summer phytoplankton blooms in the fjords. However, the dynamics of iron (Fe), an essential micronutrient for primary production, remain largely unstudied in glacial fjords. To investigate the role of subglacial discharge plumes in Fe supply processes in glacial fjords, a comprehensive survey of Bowdoin Fjord, adjacent to the marine‐terminating Bowdoin Glacier in northwestern Greenland, was conducted. The subglacial discharge of Fe‐rich meltwater induces a buoyancy‐driven upwelling plume in front of the glacier that entrains nutrient‐rich Arctic‐ and Atlantic‐origin waters. The plume water potentially carried 4.5–8.7 × 10⁷ g day⁻¹ of total dissolvable Fe out of Bowdoin Fjord in summer. The concentration of dissolved Fe (dFe) in the plume water (~15.6 nmol kg⁻¹) was 4 times higher than that in the water in the outer part of the fjord (~3.8 nmol kg⁻¹). The dFe:nitrate + nitrite ratio (mmol mol⁻¹) in the plume water varied between 0.58 and 3.2, several orders of magnitude higher than the phytoplankton cellular Fe:nitrate ratio estimated using the hypothetical Fe:C ratio and observed particulate organic carbon:nitrate ratio of the fjord. Hence, the plume water is replete with Fe with respect to phytoplankton demands. Subglacial discharge drives the upwelling of Fe and macronutrients toward the euphotic zone, which is vital for the generation of summer phytoplankton growth in glacial fjords.

中文翻译：

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冰期下的铁水供应到西北格陵兰岛一个海洋终结冰川前部的峡湾

格陵兰的冰川峡湾由于来自冰川的融水径流而显示出高生产力。与终止于海洋的冰川前的冰川下排放羽流相关的大量营养素动态变化（硝酸盐，磷酸盐和硅酸盐的动态）被认为是峡湾夏季浮游植物开花的重要驱动力。然而，在冰河峡湾中，铁（Fe）的动力学是主要生产中必不可少的微量营养元素，但仍未得到研究。为了调查冰川下冰柱羽流在Fe供给过程中的作用，对格陵兰西北部以海洋为终点的Bowdoin冰川附近的Bowdoin峡湾进行了全面调查。富含铁的融水的冰川下排放在冰川前部诱发了浮力驱动的上升流，并带走了营养丰富的北极和大西洋水。羽状水可能携带4.5–8.7×10夏季从Bowdoin峡湾排出的⁷  g ^-1总可溶铁。溶解的Fe（DFE）在羽水（〜15.6纳摩尔公斤浓度^-1）高于4倍，在水在峡湾的外部部分（〜3.8纳摩尔千克^-1）。dFe：硝酸盐+亚硝酸盐比率（mmol mol ^-1）在羽状水中的变化范围在0.58至3.2之间，比使用假设的Fe：C比和观察到的峡湾颗粒有机碳：硝酸盐比估算的浮游植物细胞Fe：硝酸盐比高出几个数量级。因此，就浮游植物的需求而言，羽状水富含铁。冰期下的排放驱使铁和大量营养素向上流向富营养区，这对于冰川峡湾夏季浮游植物的生长至关重要。