Enhanced trace element mobilization by Earth's ice sheets

SALSA Science Team

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)31648-31659
Number of pages12
JournalProceedings of the National Academy of Sciences of the United States of America
Volume117
Issue number50
DOIs
StatePublished - Dec 15 2020

Bibliographical note

Funding Information:
ACKNOWLEDGMENTS. This research is part of European Commission Horizon 2020 Marie Skłodowska-Curie Actions Fellowship ICICLES (Iron and Carbon Interactions and Biogeochemical CycLing in Subglacial EcosystemS) Grant 793962 (to J.R.H.). Antarctic work was funded under the Subglacial Antarctic Lakes Scientific Access (SALSA) project through US NSF Grants 1543537 (to M.L.S., J.C.P., and J.E.D.) and 1543453 (to W.B.L.). The Greenland research was funded by UK Natural Environment Research Council Standard Grant NE/I008845/1 (to J.L.W. and M.T.), Leverhulme Trust Research Grant RPG-2016-439 (to J.L.W.), and a Royal Society Wolfson Merit Award (to J.L.W.). A.S. was supported by NASA Earth and Space Science Fellowship 80NSSC18K1266. We thank all those involved with fieldwork at Leverett camp and the SALSA project. We thank A. Chiuchiolo for conducting DIC analysis for SALSA; analytical support from Dr. M. Cooper at the National Oceanography Centre, United Kingdom, Plasma Mass Spectrometry Laboratory; and G. White in the geochemistry group at the National High Magnetic Field Geochemistry Laboratory, which is supported by NSF Grant DMR-1644779 and the State of Florida. We are grateful for the comments and input from T. Vick-Majors, R. Venturelli, and G. Lamarche-Gagnon on an earlier draft of the manuscript.

Funding Information:
This research is part of European Commission Horizon 2020 Marie Sk?odowska-Curie Actions Fellowship ICICLES (Iron and Carbon Interactions and Biogeochemical CycLing in Subglacial EcosystemS) Grant 793962 (to J.R.H.). Antarctic work was funded under the Subglacial Antarctic Lakes Scientific Access (SALSA) project through US NSF Grants 1543537 (to M.L.S., J.C.P., and J.E.D.) and 1543453 (to W.B.L.). The Greenland research was funded by UK Natural Environment Research Council Standard Grant NE/I008845/1 (to J.L.W. and M.T.), Leverhulme Trust Research Grant RPG-2016-439 (to J.L.W.), and a Royal Society Wolfson Merit Award (to J.L.W.). A.S. was supported by NASA Earth and Space Science Fellowship 80NSSC18K1266. We thank all those involved with fieldwork at Leverett camp and the SALSA project. We thank A. Chiuchiolo for conducting DIC analysis for SALSA; analytical support from Dr. M. Cooper at the National Oceanography Centre, United Kingdom, Plasma Mass Spectrometry Laboratory; and G. White in the geochemistry group at the National High Magnetic Field Geochemistry Laboratory, which is supported by NSF Grant DMR-1644779 and the State of Florida. We are grateful for the comments and input from T. Vick-Majors, R. Venturelli, and G. Lamarche-Gagnon on an earlier draft of the manuscript.

Publisher Copyright:
© 2020 National Academy of Sciences. All rights reserved.

Keywords

  • Biogeochemical cycles
  • Elemental cycles
  • Ice sheets
  • Southern Ocean
  • Trace elements

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

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