title: Ice sheets as a missing source of silica to the polar oceans.
abstract: Ice sheets play a more important role in the global silicon cycle than previously appreciated. Input of dissolved and amorphous particulate silica into natural waters stimulates the growth of diatoms. Here we measure dissolved and amorphous silica in Greenland Ice Sheet meltwaters and icebergs, demonstrating the potential for high ice sheet export. Our dissolved and amorphous silica flux is 0.20 (0.06-0.79) Tmol year-1, ∼50% of the input from Arctic rivers. Amorphous silica comprises >95% of this flux and is highly soluble in sea water, as indicated by a significant increase in dissolved silica across a fjord salinity gradient. Retreating palaeo ice sheets were therefore likely responsible for high dissolved and amorphous silica fluxes into the ocean during the last deglaciation, reaching values of ∼5.5 Tmol year-1, similar to the estimated export from palaeo rivers. These elevated silica fluxes may explain high diatom productivity observed during the last glacial-interglacial period.
authors.affiliation: Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
authors.forename: Jon R
authors.initials: JR
authors.lastname: Hawkings
authors.affiliation: Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
authors.forename: Jemma L
authors.initials: JL
authors.lastname: Wadham
authors.affiliation: Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.|German Research Center for Geosciences GFZ, Telegrafenberg, Building C, 14473 Potsdam, Germany.|Department of Earth Sciences, Free University of Berlin, 12249 Berlin, Germany.
authors.forename: Liane G
authors.initials: LG
authors.lastname: Benning
authors.affiliation: School of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK.
authors.forename: Katharine R
authors.identifier: 0000-0002-0790-5895
authors.initials: KR
authors.lastname: Hendry
authors.affiliation: Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
authors.forename: Martyn
authors.identifier: 0000-0003-2071-3094
authors.initials: M
authors.lastname: Tranter
authors.affiliation: Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.|School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Tedstone
authors.affiliation: School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Nienow
authors.affiliation: Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Rob
authors.initials: R
authors.lastname: Raiswell