GEOC 11 |
| Stephan Kraemer1, Paul Borer2, and Barbara Sulzberger2. (1) Institute of Terrestrial Ecology, ETH Zuerich, Grabenstrasse 3, Schlieren, CH-8952, Switzerland, (2) Department of Limnology, Swiss Federal Institute for Environmental Science and Technology (EAWAG), Ueberlandstrasse 133, P.O. Box 611, CH-8600 Duebendorf, Switzerland |
| Primary productivity in ‘high nutrient low chlorophyll’ (HNLC) ocean areas is limited by the trace nutrient iron. An important source of iron in HNLC regions is the dissolution of iron bearing minerals that are introduced into the marine system as atmospheric dust. The soluble iron is predominantly complexed by strong iron binding ligands such as siderophores. Here we present observations of light induced dissolution rates of iron oxides in the presence of siderophores. We have chosen two siderophores for this study: desferrioxamine-B (DFO-B) is known not accelerate photo reduction of iron in solution; soluble aerobactin iron complexes are photo-reactive resulting in photolysis of the ligand and iron reduction. Both siderophores significantly accelerate light-induced dissolution kinetics of lepidocrocite in deaerated and aerated suspensions. Both siderophores also accelerated oxalate-promoted light-induced dissolution of lepidocrocite and goethite in deaerated and aerated solutions. In all cases a key function of the siderophore is the acceleration of the rate determining detachment of Fe(II) from iron oxide surfaces. |
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Chemistry of Metals in Terrestrial and Aquatic Systems
1:25 PM-5:05 PM, Sunday, March 28, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |