|Determining the chemical speciation of marine particulate iron using synchrotron x-ray techniques: Implications for source and bioavailability|
Of the total iron in the open ocean, up to 90% is found in the particulate form. The speciation of dissolved iron has been shown, using electrochemical methods, to be dominated overwhelmingly (>99%) by organically bound compounds. The particulate phase is a larger reservoir of iron in the ocean, but its bioavailability is an open question. Synchrotron X-ray Absorption Spectroscopy (XAS) is a very promising technique for determining the speciation of particulate iron since it is sensitive to the valence of iron as well as to the actual bonding structure of iron atoms within molecules and minerals.