HR: 11:20h
AN: B12A-05    [Abstracts]
TI: Macroscopic and Spectroscopic Analysis of Lanthanide Adsorption to Bacterial Cells
AU: * Ngwenya, B T
EM: bryne.ngwenya@ed.ac.uk
AF: University of Edinburgh, School of GeoSciences, West Mains Road, Edinburgh, EH9 3JW, United Kingdom
AU: Mosselmans, J F
EM: fred.mosselmans@diamond.ac.uk
AF: Diamond Light Source Ltd, Diamond House, Chilton, Didcot, OX11 0DE, United Kingdom
AU: Magennis, M
EM: marisa.magennis@ed.ac.uk
AF: University of Edinburgh, School of GeoSciences, West Mains Road, Edinburgh, EH9 3JW, United Kingdom
AU: Atkinson, K D
EM: Kirk.Atkinson@diamond.ac.uk
AF: Diamond Light Source Ltd, Diamond House, Chilton, Didcot, OX11 0DE, United Kingdom
AU: Tourney, J
EM: J.Tourney@sms.ed.ac.uk
AF: University of Edinburgh, School of GeoSciences, West Mains Road, Edinburgh, EH9 3JW, United Kingdom
AB: The adsorptive behaviour of lanthanides is increasingly becoming a major focus of research, partly because lanthanides are good analogues for understanding the behaviour of the more problematic actinides, and also because when studied as a suite, their fractionation patterns make them important indicators of geochemical processes, including possible biosignature applications. We have combined macroscopic adsorption modelling, spectroscopic analysis and linear free energy relationships to explore mechanisms by which lanthanides interact with bacterial cell surfaces. Macroscopic adsorption modelling suggests that all lanthanides preferentially adsorb to phosphate sites below neutral pH values. However, carboxyl complexation also explains most of the adsorption density below pH ~5. Furthermore, analysis of the recovered stability constants using linear free energy relationships showed that most of the adsorption density could be predicted using stability constants estimated using fulvic acid complexation. Nevertheless, EXAFS analysis confirmed mixed-mode co-ordination, showing lanthanide co- ordination to phosphate sites at low pH and low metal to biomass ratios, with secondary involvement of carboxyl sites at pH values greater than 5. This study therefore demonstrates the importance of combining direct spectroscopic measurement with modelling in determining metal adsorption sites.
DE: 0409 Bioavailability: chemical speciation and complexation
DE: 0412 Biogeochemical kinetics and reaction modeling (0414, 0793, 1615, 4805, 4912)
DE: 0418 Bioremediation
DE: 0461 Metals
DE: 0489 Trace element cycling (4875)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting