GEOC 58 |
| V. Salters and Jeroen E Sonke. Department of Geological Sciences and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306-4100 |
| We coupled capillary electrophoresis (CE) to an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) to study non-labile metal speciation in aquatic samples. We separated EDTA-REE and organic-REE complexes (ligand competition) and determined conditional equilibrium binding constants (Kc) and kinetic rate constants for all REEs with Humic (HA) and Fulvic Acids (FA) as a function of pH6-9 and 0.01-0.1 mol/L ionic strength (IS). REE-HA binding is in general two order of magnitude stronger than REE-FA, and binding strengths increase with pH and decreases with IS. LogKc’s increase 30-1000 fold with increasing atomic number. This is the first comprehensive metal binding dataset between REE and DOM, and the first experimental evidence for differential equilibrium and kinetic binding between REEs and DOM. The observed lanthanide fractionation with organic matter provides a mechanism that can explain much of the features of the REE patterns in aquatic systems. |
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Chemistry of Metals in Terrestrial and Aquatic Systems
8:00 AM-11:30 AM, Tuesday, March 30, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |