Non-linear response of summertime marine productivity to increased meltwater discharge around Greenland
Non-linear response of summertime marine productivity to increased meltwater discharge around Greenland
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DOI：
10.1038/s41467-018-05488-8
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发表时间：
2018-08-14
影响因子：
16.6
通讯作者：
Achterberg, E. P.
中科院分区：
文献类型：
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作者：
Hopwood, M. J.;Carroll, D.;Achterberg, E. P.
人们认为格陵兰冰盖（GrIS）的径流可以通过向沿海水域添加生物必需的铁和硅酸来提高海洋生产力。然而，实验数据表明，硝酸盐是格陵兰岛周围受融水影响的地区夏季主要的生长限制资源。虽然融水含有低浓度的硝酸盐，但来自海洋终端冰川的冰下排放羽流会从深层海水中夹带大量硝酸盐。在这里，我们使用冰下排放羽流模型来表征这些羽流中海水夹带产生的硝酸盐通量。 12 个海洋终止冰川的上升通量估计超过 GrIS 排放总硝酸盐通量的 1000%。这种羽流上升效应对冰川接地线深度高度敏感。对于格陵兰岛的大部分海洋终止冰川来说，硝酸盐通量将随着它们的退缩而减少。即使排放量增加，这种下降也会发生，从而对硝酸盐可用性和夏季海洋生产力产生负面影响。
Runoff from the Greenland Ice Sheet (GrIS) is thought to enhance marine productivity by adding bioessential iron and silicic acid to coastal waters. However, experimental data suggest nitrate is the main summertime growth-limiting resource in regions affected by meltwater around Greenland. While meltwater contains low nitrate concentrations, subglacial discharge plumes from marine-terminating glaciers entrain large quantities of nitrate from deep seawater. Here, we characterize the nitrate fluxes that arise from entrainment of seawater within these plumes using a subglacial discharge plume model. The upwelled flux from 12 marine-terminating glaciers is estimated to be >1000% of the total nitrate flux from GrIS discharge. This plume upwelling effect is highly sensitive to the glacier grounding line depth. For a majority of Greenland's marine-terminating glaciers nitrate fluxes will diminish as they retreat. This decline occurs even if discharge volume increases, resulting in a negative impact on nitrate availability and thus summertime marine productivity.