SS4.06 Speciation, Bioavailability, and Impacts of Atmospheric Trace Metals in Aquatic Systems
Date: Wednesday, June 12, 2002
Time: 2:30:00 PM
Location: Esquimalt
 
ZhangH, Lancaster University, Lancaster, United Kingdom, h.zhang@lancaster.ac.uk
Scally, S, , Lancaster University, Lancaster, United Kingdom, s.scally@lancaster.ac.uk
Davison, W, , Lancaster University, Lancaster, United Kingdom, w.davison@lancaster.ac.uk
 
AN IN SITU KINETIC PROBE FOR METAL SPECIATION AND BIOAVAILABILITY
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Biological uptake of metals depends on a) their chemical speciation and b) the relative importance of the transfer kinetics across the cell membrane compared to the rates of mass transport and the rates of supply from metal complexes and/or particles. The precise measurement of metal speciation in natural waters and the understanding of the kinetics of metal release from ligands and particles in relation to bioavailability have been hampered by the lack of simple, realistic procedures. The emerging technique of diffusive gradients in thin-films (DGT) provides a simple tool for characterising speciation and kinetics in situ. In DGT metals are accumulated at a resin gel after passing through a diffusive gel layer. Size-based discrimination of labile inorganic and organic complexes in situ in natural waters can be achieved by varying the pore size of the diffusive gel. DGT’s potential as a kinetic probe is illustrated by measurements on well-defined solutions of metals and ligands. The dissociation rate constants of metal complexes were determined within the DGT lability detection window and the results agreed well with the published values.