Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba

Kimberley K. Mayfield, Anton Eisenhauer, Danielle P. Santiago Ramos, John A. Higgins, Tristan J. Horner, Maureen Auro, Tomas Magna, Nils Moosdorf, Matthew A. Charette, Meagan Eagle Gonneea, Carolyn E. Brady, Nemanja Komar, Bernhard Peucker-Ehrenbrink, Adina Paytan

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Groundwater-derived solute fluxes to the ocean have long been assumed static and subordinate to riverine fluxes, if not neglected entirely, in marine isotope budgets. Here we present concentration and isotope data for Li, Mg, Ca, Sr, and Ba in coastal groundwaters to constrain the importance of groundwater discharge in mediating the magnitude and isotopic composition of terrestrially derived solute fluxes to the ocean. Data were extrapolated globally using three independent volumetric estimates of groundwater discharge to coastal waters, from which we estimate that groundwater-derived solute fluxes represent, at a minimum, 5% of riverine fluxes for Li, Mg, Ca, Sr, and Ba. The isotopic compositions of the groundwater-derived Mg, Ca, and Sr fluxes are distinct from global riverine averages, while Li and Ba fluxes are isotopically indistinguishable from rivers. These differences reflect a strong dependence on coastal lithology that should be considered a priority for parameterization in Earth-system models.

Original languageEnglish (US)
Article number148
JournalNature communications
Volume12
Issue number1
DOIs
StatePublished - Dec 2021

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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