New study shows Antarctic melting an important source of iron to coastal ecosystems

Primary production in up to 40 % of the Earth's oceans are thought to be limited by a lack of iron, largely due to its low solubility and a dependence upon weathered rock as the principal source. For these reasons, researchers have argued how dust and icebergs are the most important sources of new iron for marine ecosystems surrounding the frozen Antarctic continent. Since other nutrients are already abundant in these seas, marked increases in primary production can occur when iron is transferred into the sea, resulting in the globally important Southern Ocean Ecosystem.

Work by Andy Hodson and Aga Nowak shows that surface melting is contributing far more significantly to the iron entering these hotspots of biological production than hitherto realised. The research involved visiting several island groups in the Scotia Sea region, measuring the concentrations of iron in surface runoff and examining other chemical parameters such as dissolved organic carbon which control them. When they used models of surface meltwater production to estimate the total export of iron by meltwater, they were surprised to find that it readily exceeds inputs from icebergs (and dust) across the Antarctic Peninsula region. They also found that the amount of iron transferred by meltwater runoff could increase almost exponentially in response to the warming predicted for the rest of this century.

More research is therefore required to document the fate of this additional iron and to establish precisely how it influences the Southern Ocean ecosystem.


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