title: Distinct iron isotopic signatures and supply from marine sediment dissolution.
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.
authors.affiliation: Ocean and Earth Science, University of Southampton, National Oceanography Centre, European Way, Southampton SO14 3ZH, UK. wbh@noc.soton.ac.uk
authors.forename: William B
authors.initials: WB
authors.lastname: Homoky
authors.forename: Seth G
authors.initials: SG
authors.lastname: John
authors.forename: Tim M
authors.initials: TM
authors.lastname: Conway
authors.forename: Rachel A
authors.initials: RA
authors.lastname: Mills
mesh_terms: D001272:Atmosphere / Q000737:chemistry; D002980:Climate; D019015:Geologic Sediments / Q000737:chemistry*; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D007503:Iron Isotopes; D009792:Oceans and Seas; D012623:Seawater / Q000737:chemistry*; D012995:Solubility; D013019:South Africa; D014919:Wind
chemical_list: D007503:Iron Isotopes; D007501:Iron