Distinct Iron Isotopic Signatures and Supply from Marine Sediment Dissolution

William B. Homoky, Seth G. John, Tim M. Conway, Rachel A. Mills

Research output: Contribution to journalArticlepeer-review

Abstract

Oceanic iron inputs must be traced and quantified to learn how they affect primary productivity and climate. Chemical reduction of iron in continental margin sediments provides a substantial dissolved flux to the oceans, which is isotopically lighter than the crust, and so may be distinguished in seawater from other sources, such as wind-blown dust. However, heavy iron isotopes measured in seawater have recently led to the proposition of another source of dissolved iron from ‘non-reductive’ dissolution of continental margins. Here we present the first pore water iron isotope data from a passive-tectonic and semi-arid ocean margin (South Africa), which reveals a smaller and isotopically heavier flux of dissolved iron to seawater than active-tectonic and dysoxic continental margins. These data provide in situ evidence of non-reductive iron dissolution from a continental margin, and further show that geological and hydro-climatic factors may affect the amount and isotopic composition of iron entering the ocean.

Original languageAmerican English
JournalNature Communications
Volume7
DOIs
StatePublished - Jul 1 2013
Externally publishedYes

Disciplines

  • Earth Sciences

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