Rapid and sensitive response of Greenland’s groundwater system to ice sheet change
Rapid and sensitive response of Greenland’s groundwater system to ice sheet change
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DOI：
10.1038/s41561-021-00813-1
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发表时间：
2021-09
影响因子：
18.3
通讯作者：
L. Liljedahl;T. Meierbachtol;J. Harper;D. van As;J. Näslund;J. Selroos;J. Saito;S. Follin;T. Ruskeeniemi;A. Kontula;N. Humphrey
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文献类型：
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作者：
L. Liljedahl;T. Meierbachtol;J. Harper;D. van As;J. Näslund;J. Selroos;J. Saito;S. Follin;T. Ruskeeniemi;A. Kontula;N. Humphrey
格陵兰冰盖质量损失正在影响相连的陆地和海洋水文系统，并产生全球性后果。地下水是北极水循环的关键组成部分，位于 1.7e6km2 冰盖下方，形成近海淡水储备。然而，尽管格陵兰岛面积广阔，但格陵兰岛地下水对持续冰盖变化的反应尚不清楚。在这里，我们展示了格陵兰冰盖下深层地下水状况的现场观测，这些观测是在冰盖边缘下倾斜的 651 米长的冰期基岩钻孔中获得的。我们发现格陵兰岛的地下水系统对相对较小的冰盖强迫反应迅速而敏感。水头在多年、季节和昼夜时间尺度上明显变化，我们将其解释为对与上覆冰载荷和冰盖水文变化相关的冰/床界面处流体压力的响应。我们发现在八年的观察期内水头的系统性下降主要与冰盖质量损失有关。正在进行和未来的冰变薄可能会降低地下水排放率，对海底淡水排放、峡湾淡水输送和北极生物地球化学通量产生潜在影响。
Greenland Ice Sheet mass loss is impacting connected terrestrial and marine hydrologic systems with global consequences. Groundwater is a key component of water cycling in the Arctic, underlying the 1.7e6km2ice sheet and forming offshore freshwater reserves. However, despite its vast extent, the response of Greenland’s groundwater to ongoing ice sheet change is unknown. Here we present in-situ observations of deep groundwater conditions under the Greenland Ice Sheet, obtained in a 651-metre-long proglacial bedrock borehole angled under the ice sheet margin. We find that Greenland’s groundwater system responds rapidly and sensitively to relatively minor ice sheet forcing. Hydraulic head clearly varies over multi-annual, seasonal and diurnal timescales, which we interpret as a response to fluid pressure forcing at the ice/bed interface associated with changes in overlying ice loading and ice sheet hydrology. We find a systematic decline in hydraulic head over the eight-year observational period is linked primarily to ice sheet mass loss. Ongoing and future ice thinning will probably reduce groundwater discharge rates, with potential impacts to submarine freshwater discharge, freshwater delivery to fjords and biogeochemical fluxes in the Arctic.