title: Constraints on soluble aerosol iron flux to the Southern Ocean at the Last Glacial Maximum.
abstract: Relief of iron (Fe) limitation in the Southern Ocean during ice ages, with potentially increased carbon storage in the ocean, has been invoked as one driver of glacial-interglacial atmospheric CO2 cycles. Ice and marine sediment records demonstrate that atmospheric dust supply to the oceans increased by up to an order of magnitude during glacial intervals. However, poor constraints on soluble atmospheric Fe fluxes to the oceans limit assessment of the role of Fe in glacial-interglacial change. Here, using novel techniques, we present estimates of water- and seawater-soluble Fe solubility in Last Glacial Maximum (LGM) atmospheric dust from the European Project for Ice Coring in Antarctica (EPICA) Dome C and Berkner Island ice cores. Fe solubility was very variable (1-42%) during the interval, and frequently higher than typically assumed by models. Soluble aerosol Fe fluxes to Dome C at the LGM (0.01-0.84 mg m(-2) per year) suggest that soluble Fe deposition to the Southern Ocean would have been ≥10 × modern deposition, rivalling upwelling supply.
authors.affiliation: 1] Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK [2] British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
authors.forename: T M
authors.identifier: 0000000230699786
authors.initials: TM
authors.lastname: Conway
authors.affiliation: 1] Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK [2] British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
authors.forename: E W
authors.identifier: 0000000259148531
authors.initials: EW
authors.lastname: Wolff
authors.affiliation: British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
authors.forename: R
authors.initials: R
authors.lastname: Röthlisberger
authors.affiliation: British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK.
authors.forename: R
authors.identifier: 0000000253728148
authors.initials: R
authors.lastname: Mulvaney
authors.affiliation: Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.
authors.forename: H E
authors.initials: HE
authors.lastname: Elderfield