Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans.
The Greenland and Antarctic Ice Sheets cover ~ 10% of global land surface, but are rarely considered as active components of the global iron cycle. The ocean waters around both ice sheets harbour highly productive coastal ecosystems, many of which are iron limited. Measurements of iron concentrations in subglacial runoff from a large Greenland Ice Sheet catchment reveal the potential for globally significant export of labile iron fractions to the near-coastal euphotic zone. We estimate that the flux of bioavailable iron associated with glacial runoff is 0.40-2.54 Tg per year in Greenland and 0.06-0.17 Tg per year in Antarctica. Iron fluxes are dominated by a highly reactive and potentially bioavailable nanoparticulate suspended sediment fraction, similar to that identified in Antarctic icebergs. Estimates of labile iron fluxes in meltwater are comparable with aeolian dust fluxes to the oceans surrounding Greenland and Antarctica, and are similarly expected to increase in a warming climate with enhanced melting.
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
Jon R
JR
Hawkings
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
Jemma L
JL
Wadham
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
Martyn
M
Tranter
Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
Rob
R
Raiswell
Cohen Biogeochemistry Laboratory, School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK.
Liane G
LG
Benning
School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Southampton SO14 3ZH, UK.
Peter J
PJ
Statham
School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK.
Andrew
A
Tedstone
School of Geoscience, University of Edinburgh, Edinburgh EH8 9XP, UK.
Peter
P
Nienow
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
Katherine
K
Lee
Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK.
Jon
J
Telling
D000864:Antarctic Regions; D057231:Climate Change; D006116:Greenland; D046448:Ice Cover / Q000737:chemistry*; D007501:Iron; D053768:Metal Nanoparticles / Q000737:chemistry*; D009792:Oceans and Seas
D007501:Iron