A newly-discovered source of oceanic bioavailable iron could have a major impact our understanding of marine food chains and global warming. A UK team has discovered that summer meltwaters from ice sheets are rich in iron, which will have important implications on phytoplankton growth. The findings are reported in the journal Nature Communications on 21st May, 2014*.
It is well known that bioavailable iron boosts phytoplankton growth in many of the Earth's oceans. In turn phytoplankton capture carbon thus buffering the effects of global warming. The plankton also feed into the bottom of the oceanic food chain, thus providing a food source for marine animals.
The team, comprising researchers from the Universities of Bristol, Leeds, Edinburgh and the National Oceanography Centre, collected meltwater discharged from the 600 km2 Leverett Glacier** in Greenland over the summer of 2012, which was subsequently tested for bioavailable iron content. The researchers found that the water exiting from beneath the melting ice sheet contained significant quantities of previously-unconsidered bioavailable iron. This means that the polar oceans receive a seasonal iron boost as the glaciers melt.
Jon Hawkings (Bristol), the lead author, said
"The Greenland and Antarctic Ice Sheets cover around 10% of global land surface. Iron exported in icebergs from these ice sheets have been recognised as a source of iron to the oceans for some time. Our finding that there is also significant iron discharged in runoff from large ice sheet catchments is new. "
"This means that relatively high iron concentrations are released from the ice sheet all summer, providing a continuous source of iron to the coastal ocean"
Iron is one of the most important biochemical elements, due to its impact on ocean productivity. Despite being the fourth most abundant element in the Earth's crust, it is mostly not biologically available because it is larg
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European Association of Geochemistry