Hobart

Seminar abstract

Monday 4 December 2006, 11.30 am (Tas time)
CSIRO Conference Rooms A and B, Hobart

Dr Kevin Wilkinson
Concordia University, Montreal.

Bioavailability of trace metals to micro-organisms: when does the physicochemistry limit the biological transport?

An important challenge in environmental biogeochemistry is the determination of the bioavailability of toxic and essential trace compounds in natural media. It is now clear that chemical speciation must be taken into account when predicting bioavailability.

Over the past 20 years, equilibrium models (free ion activity model, biotic ligand model) have been increasingly developed to describe the bioavailability of trace metals in environmental systems, despite the fact that environmental systems are always dynamic and rarely at equilibrium. Recently, it has become clear that biological, physical and chemical reactions occurring in the immediate proximity of the biological surface also play an important role in controlling trace metal bioavailability through shifts in the limiting biouptake fluxes. Indeed, for microorganisms, examples of biological (transport across membrane), chemical (dissociation kinetics of metal complexes) and physical (diffusion) limitation can be demonstrated. Furthermore, the organism can employ a number of biological internalization strategies to get around limitations that are imposed on it by the physicochemistry of the medium.

This talk will discuss several important concepts that must be taken into account when relating the chemistry of the environmental medium of interest with the biology of trace metal accumulation. Several examples will be presented by focusing on two microalga: Chlorella kesslerii and Chlamydomonas reinhardtii . It will be concluded that the prediction of trace metal bioavailability will require multidisciplinary advances in our understanding of the reactions occurring at and near the biological interface.

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Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Karen Wild-Allen, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5010
Piers Dunstan, (Biological seminars) CSIRO Marine and Atmospheric Research
(03) 6232 5382
Annabel Ozimec (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5462
Sandra Zicus, Antarctic Climate and Ecosystems CRC (03) 6226 7888
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 28/11/06