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.
|Title||Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba|
|Authors||Kimberly Mayfield, Anton Eisenhauer, Danielle P. Santiago Ramos, John A. Higgins, Tristan Horner, Maureen Auro, Tomas Magna, Nils Moosdorf, Matthew Charette, Meagan Gonneea Eagle, Carolyn Brady, Nemanja Komar, Bernhard Peucker-Ehrenbrink, Adina Paytan|
|Publication Subtype||Journal Article|
|Series Title||Nature Communications|
|Record Source||USGS Publications Warehouse|
|USGS Organization||Woods Hole Coastal and Marine Science Center|