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Sunlight Affects Iron Cycles In The Ocean
Add photochemistry to the growing list of factors known to play a role in the complicated biogeochemical cycling of iron in the oceans. When exposed to sunlight, complexes of iron(III) with siderophores containing -hydroxy acids undergo photochemical changes, causing iron uptake by marine microorganisms to occur more readily, according to California researchers [Nature, 413, 409 (2001)].
Siderophores--Greek for "iron loving"--are organic ligands produced by aerobic microorganisms to help them capture iron. UC Santa Barbara chemistry professor Alison Butler and coworkers find that exposing the aquachelin family of Fe(III) siderophores from oceanic bacteria to light causes the hydrophobic tails of the siderophores to split off from the hydrophilic peptide heads. At the same time, the Fe(III) is reduced to Fe(II). In ocean water, iron in the photoproducts is taken up more readily than the iron in the original complex. Such cycling, the researchers write, "is likely to be a fundamental feature of the marine biogeochemistry of iron, strongly influencing the interaction of marine biota with this critical micronutrient."
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Copyright © 2001 American Chemical Society