Influence of glacial meltwater on global seawater δ234U

Carli A. Arendt, Sarah M. Aciego, Kenneth W.W. Sims, Sarah B. Das, Cody Sheik, Emily I. Stevenson

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We present the first published uranium-series measurements from modern Greenland Ice Sheet (GrIS) runoff and proximal seawater, and investigate the influence of glacial melt on global seawater δ234U over glacial-interglacial (g-ig) timescales. Climate reconstructions based on closed-system uranium-thorium (U/Th) dating of fossil corals assume U chemistry of seawater has remained stable over time despite notable fluctuations in major elemental compositions, concentrations, and isotopic compositions of global seawater on g-ig timescales. Deglacial processes increase weathering, significantly increasing U-series concentrations and changing the δ234U of glacial meltwater. Analyses of glacial discharge from GrIS outlet glaciers indicate that meltwater runoff has elevated U concentrations and differing 222Rn concentrations and δ234U compositions, likely due to variations in subglacial residence time. Locations with high δ234U have the potential to increase proximal seawater δ234U. To better understand the impact of bulk glacial melt on global seawater δ234U over time, we use a simple box model to scale these processes to periods of extreme deglaciation. We account for U fluxes from the GrIS, Antarctica, and large Northern Hemisphere Continental Ice Sheets, and assess sensitivity by varying melt volumes, duration and U flux input rates based on modern subglacial water U concentrations and compositions. All scenarios support the hypothesis that global seawater δ234U has varied by more than 1‰ through time as a function of predictable perturbations in continental U fluxes during g-ig periods.

Original languageEnglish (US)
Pages (from-to)102-115
Number of pages14
JournalGeochimica et Cosmochimica Acta
Volume225
DOIs
StatePublished - Mar 15 2018

Fingerprint

Seawater
meltwater
seawater
Ice
ice sheet
interglacial
Uranium
melt
Fluxes
Chemical analysis
Runoff
uranium
runoff
Thorium
timescale
Glaciers
thorium
Weathering
deglaciation
residence time

Keywords

  • Glacial-interglacial
  • Glaciology
  • Greenland ice sheet
  • Meltwater
  • Paleoclimatology
  • Radiogenic isotopes
  • Seawater chemistry
  • Subglacial processes
  • Uranium

Cite this

Arendt, C. A., Aciego, S. M., Sims, K. W. W., Das, S. B., Sheik, C., & Stevenson, E. I. (2018). Influence of glacial meltwater on global seawater δ234U. Geochimica et Cosmochimica Acta, 225, 102-115. https://doi.org/10.1016/j.gca.2018.01.007

Influence of glacial meltwater on global seawater δ234U. / Arendt, Carli A.; Aciego, Sarah M.; Sims, Kenneth W.W.; Das, Sarah B.; Sheik, Cody; Stevenson, Emily I.

In: Geochimica et Cosmochimica Acta, Vol. 225, 15.03.2018, p. 102-115.

Research output: Contribution to journalArticle

Arendt, CA, Aciego, SM, Sims, KWW, Das, SB, Sheik, C & Stevenson, EI 2018, 'Influence of glacial meltwater on global seawater δ234U', Geochimica et Cosmochimica Acta, vol. 225, pp. 102-115. https://doi.org/10.1016/j.gca.2018.01.007
Arendt, Carli A. ; Aciego, Sarah M. ; Sims, Kenneth W.W. ; Das, Sarah B. ; Sheik, Cody ; Stevenson, Emily I. / Influence of glacial meltwater on global seawater δ234U. In: Geochimica et Cosmochimica Acta. 2018 ; Vol. 225. pp. 102-115.
@article{26833f993c4d45bcb1c0be644a7b88b3,
title = "Influence of glacial meltwater on global seawater δ234U",
abstract = "We present the first published uranium-series measurements from modern Greenland Ice Sheet (GrIS) runoff and proximal seawater, and investigate the influence of glacial melt on global seawater δ234U over glacial-interglacial (g-ig) timescales. Climate reconstructions based on closed-system uranium-thorium (U/Th) dating of fossil corals assume U chemistry of seawater has remained stable over time despite notable fluctuations in major elemental compositions, concentrations, and isotopic compositions of global seawater on g-ig timescales. Deglacial processes increase weathering, significantly increasing U-series concentrations and changing the δ234U of glacial meltwater. Analyses of glacial discharge from GrIS outlet glaciers indicate that meltwater runoff has elevated U concentrations and differing 222Rn concentrations and δ234U compositions, likely due to variations in subglacial residence time. Locations with high δ234U have the potential to increase proximal seawater δ234U. To better understand the impact of bulk glacial melt on global seawater δ234U over time, we use a simple box model to scale these processes to periods of extreme deglaciation. We account for U fluxes from the GrIS, Antarctica, and large Northern Hemisphere Continental Ice Sheets, and assess sensitivity by varying melt volumes, duration and U flux input rates based on modern subglacial water U concentrations and compositions. All scenarios support the hypothesis that global seawater δ234U has varied by more than 1‰ through time as a function of predictable perturbations in continental U fluxes during g-ig periods.",
keywords = "Glacial-interglacial, Glaciology, Greenland ice sheet, Meltwater, Paleoclimatology, Radiogenic isotopes, Seawater chemistry, Subglacial processes, Uranium",
author = "Arendt, {Carli A.} and Aciego, {Sarah M.} and Sims, {Kenneth W.W.} and Das, {Sarah B.} and Cody Sheik and Stevenson, {Emily I.}",
year = "2018",
month = "3",
day = "15",
doi = "10.1016/j.gca.2018.01.007",
language = "English (US)",
volume = "225",
pages = "102--115",
journal = "Geochmica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Limited",

}

TY - JOUR

T1 - Influence of glacial meltwater on global seawater δ234U

AU - Arendt, Carli A.

AU - Aciego, Sarah M.

AU - Sims, Kenneth W.W.

AU - Das, Sarah B.

AU - Sheik, Cody

AU - Stevenson, Emily I.

PY - 2018/3/15

Y1 - 2018/3/15

N2 - We present the first published uranium-series measurements from modern Greenland Ice Sheet (GrIS) runoff and proximal seawater, and investigate the influence of glacial melt on global seawater δ234U over glacial-interglacial (g-ig) timescales. Climate reconstructions based on closed-system uranium-thorium (U/Th) dating of fossil corals assume U chemistry of seawater has remained stable over time despite notable fluctuations in major elemental compositions, concentrations, and isotopic compositions of global seawater on g-ig timescales. Deglacial processes increase weathering, significantly increasing U-series concentrations and changing the δ234U of glacial meltwater. Analyses of glacial discharge from GrIS outlet glaciers indicate that meltwater runoff has elevated U concentrations and differing 222Rn concentrations and δ234U compositions, likely due to variations in subglacial residence time. Locations with high δ234U have the potential to increase proximal seawater δ234U. To better understand the impact of bulk glacial melt on global seawater δ234U over time, we use a simple box model to scale these processes to periods of extreme deglaciation. We account for U fluxes from the GrIS, Antarctica, and large Northern Hemisphere Continental Ice Sheets, and assess sensitivity by varying melt volumes, duration and U flux input rates based on modern subglacial water U concentrations and compositions. All scenarios support the hypothesis that global seawater δ234U has varied by more than 1‰ through time as a function of predictable perturbations in continental U fluxes during g-ig periods.

AB - We present the first published uranium-series measurements from modern Greenland Ice Sheet (GrIS) runoff and proximal seawater, and investigate the influence of glacial melt on global seawater δ234U over glacial-interglacial (g-ig) timescales. Climate reconstructions based on closed-system uranium-thorium (U/Th) dating of fossil corals assume U chemistry of seawater has remained stable over time despite notable fluctuations in major elemental compositions, concentrations, and isotopic compositions of global seawater on g-ig timescales. Deglacial processes increase weathering, significantly increasing U-series concentrations and changing the δ234U of glacial meltwater. Analyses of glacial discharge from GrIS outlet glaciers indicate that meltwater runoff has elevated U concentrations and differing 222Rn concentrations and δ234U compositions, likely due to variations in subglacial residence time. Locations with high δ234U have the potential to increase proximal seawater δ234U. To better understand the impact of bulk glacial melt on global seawater δ234U over time, we use a simple box model to scale these processes to periods of extreme deglaciation. We account for U fluxes from the GrIS, Antarctica, and large Northern Hemisphere Continental Ice Sheets, and assess sensitivity by varying melt volumes, duration and U flux input rates based on modern subglacial water U concentrations and compositions. All scenarios support the hypothesis that global seawater δ234U has varied by more than 1‰ through time as a function of predictable perturbations in continental U fluxes during g-ig periods.

KW - Glacial-interglacial

KW - Glaciology

KW - Greenland ice sheet

KW - Meltwater

KW - Paleoclimatology

KW - Radiogenic isotopes

KW - Seawater chemistry

KW - Subglacial processes

KW - Uranium

UR - http://www.scopus.com/inward/record.url?scp=85041470232&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85041470232&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2018.01.007

DO - 10.1016/j.gca.2018.01.007

M3 - Article

VL - 225

SP - 102

EP - 115

JO - Geochmica et Cosmochimica Acta

JF - Geochmica et Cosmochimica Acta

SN - 0016-7037

ER -