Journal article
Enhanced trace element mobilization by Earth's ice sheets.
- Hawkings JR National High Magnetic Field Laboratory Geochemistry Group, Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL 32306; jhawkings@fsu.edu.
- Skidmore ML Department of Earth Sciences, Montana State University, Bozeman, MT 59717.
- Wadham JL School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, United Kingdom.
- Priscu JC Department of Land Resources and Environmental Sciences, Bozeman, Montana State University, MT 59717.
- Morton PL National High Magnetic Field Laboratory Geochemistry Group, Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL 32306.
- Hatton JE School of Earth Sciences, University of Bristol, Bristol, BS8 1RL, United Kingdom.
- Gardner CB School of Earth Sciences, Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH 43210.
- Kohler TJ Stream Biofilm and Ecosystem Research Laboratory, School of Architecture, Civil and Environmental Engineering, École Polytechnique Fédérale de Lausanne, Lausanne CH-1015, Switzerland.
- Stibal M Department of Ecology, Faculty of Science, Charles University, CZ-12844, Prague, Czechia.
- Bagshaw EA School of Earth and Ocean Sciences, Cardiff University, Cardiff, CF10 3AT, United Kingdom.
- Steigmeyer A Department of Earth Sciences, Montana State University, Bozeman, MT 59717.
- Barker J Department of Earth and Environmental Sciences, University of Minnesota, Minneapolis, MN 55455.
- Dore JE Department of Land Resources and Environmental Sciences, Bozeman, Montana State University, MT 59717.
- Lyons WB School of Earth Sciences, Byrd Polar and Climate Research Center, The Ohio State University, Columbus, OH 43210.
- Tranter M School of Geographical Sciences, University of Bristol, Bristol, BS8 1SS, United Kingdom.
- Spencer RGM National High Magnetic Field Laboratory Geochemistry Group, Department of Earth, Ocean and Atmospheric Sciences, Florida State University, Tallahassee, FL 32306.
- 2020-11-24
Published in:
- Proceedings of the National Academy of Sciences of the United States of America. - 2020
English
Trace elements sustain biological productivity, yet the significance of trace element mobilization and export in subglacial runoff from ice sheets is poorly constrained at present. Here, we present size-fractionated (0.02, 0.22, and 0.45 µm) concentrations of trace elements in subglacial waters from the Greenland Ice Sheet (GrIS) and the Antarctic Ice Sheet (AIS). Concentrations of immobile trace elements (e.g., Al, Fe, Ti) far exceed global riverine and open ocean mean values and highlight the importance of subglacial aluminosilicate mineral weathering and lack of retention of these species in sediments. Concentrations are higher from the AIS than the GrIS, highlighting the geochemical consequences of prolonged water residence times and hydrological isolation that characterize the former. The enrichment of trace elements (e.g., Co, Fe, Mn, and Zn) in subglacial meltwaters compared with seawater and typical riverine systems, together with the likely sensitivity to future ice sheet melting, suggests that their export in glacial runoff is likely to be important for biological productivity. For example, our dissolved Fe concentration (20,900 nM) and associated flux values (1.4 Gmol y-1) from AIS to the Fe-deplete Southern Ocean exceed most previous estimates by an order of magnitude. The ultimate fate of these micronutrients will depend on the reactivity of the dominant colloidal size fraction (likely controlled by nanoparticulate Al and Fe oxyhydroxide minerals) and estuarine processing. We contend that ice sheets create highly geochemically reactive particulates in subglacial environments, which play a key role in trace elemental cycles, with potentially important consequences for global carbon cycling.
- Language
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- English
- Open access status
- closed
- Identifiers
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- DOI 10.1073/pnas.2014378117
- PMID 33229559
- Persistent URL
- https://sonar.ch/global/documents/210012
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