E-mail: chuni_chakrabarti@carleton.ca

Environmental Chemistry

1. Biogeochemistry of trace metals in the natural environment
Trace metals exist in a variety of chemical forms: free metal ions, metal ions incorporated into colloids or adsorbed onto suspended particles, small inorganic complexes and complexes with Natural Organic Matter (NOM)—each with its own unique properties. Knowledge of the metal distribution among the different physical and chemical forms (i.e. chemical speciation) is therefore essential for predicting their environmental impacts. Traditional approaches to metal speciation in the natural environment are operationally-defined (e.g. "chelex-labile" and "ASV-labile"). This simplistic approach completely neglects the complexity of freshwater systems. We propose to replace the operationally-defined categories with quantitative speciation parameters of metal complexes: dissociation rate coefficients (chemical reactivity), conditional stability constants (thermodynamic stability), and diffusion coefficients (mobility). These speciation parameters are based on the dissociation of the metal complex—a fundamental process in natural systems.

2. Bioavailability of trace metals in the freshwater environment
Because of their versatility in a wide variety of chemical reactions, many trace metals are essential micronutrients in biological systems. However, their reactivity can also lead to toxicity even at relatively low levels. This delicate limit between trace metals as micronutrients and toxicants plays a crucial role in the balance of life. Mechanistic biogeochemical models such as the Free Ion Activity Model (FIAM) and the Biotic Ligand Model (BLM) are beginning to be applied for setting site-specific acute water quality criteria. Expanding the BLM approach to chronic toxicity and to complex effluents is highly desirable from an effluent discharge point of view, but presents significant challenges in chemistry, toxicology and modelling. The current BLM does not account for the impacts of multiple metal exposure systems where the mode of action differs, nor does it account for the effects of anthropogenic ligands. We are developing the necessary chemical speciation and chronic toxicological inputs to broaden the BLM approach to metal contaminated effluents. 

Analytical Chemistry

3. Development of novel techniques for chemical speciation of trace metals in the natural environment
The techniques being developed to investigate metal speciation in aqueous environmental samples (e.g., freshwaters, rain water, snow-melt) and solid samples (e.g., fluvial sediments, soils) are: size fractionation by Cascade Ultrafiltration and physicochemical characterization by Anodic Stripping Voltammetry with a Rotating Disk Electrode, Adsorptive Cathodic Stripping Voltammetry, and Competing Ligand Exchange Methods using cation exchange resins and Inductively-Coupled Plasma - Mass Spectrometry and Graphite Furnace Atomic Absorption Spectrometry to investigate the dissociation kinetics of the metal-complexes.

 

2003	SPECIAL ISSUE of the Canadian Journal of Analytical Sciences and Spectrometry, published in my honour	Spectroscopy Society of Canada
1998	SPECIAL ISSUE of Spectrochemica Acta, Part B, published in my honour	Spectrochimica Acta
1994	Atomic Spectroscopy Award	Spectrochimica Acta
1990	July 15-21, Symposium to honour my contributions to Analytical Chemistry	The Chemical Institute of Canada
1984	The Ionnes Marcus Marci of Kronland Plaque Award	Czechoslovak Academy of Sciences
1981	The Fisher Scientific Lecture Award	The Chemical Institute of Canada
1977	The Gerhard Herzberg Award	Spectroscopy Society of Canada

RESEARCH COLLABORATORS

Dr. D.C. Grégoire Head Analytical Chemistry Research Laboratories Geological Survey of Canada Natural Resources Canada	Dr. Pat Rasmussen Research Scientist Health Canada Environment and Occupational Toxicology Division
Dr. Ewa Dabek Research Chemist Environmental Toxicology Centre Environment Canada	Professor R.J. Hudson Associate Professor Department of Natural Resources and Environmental Sciences University of Illinois USA
Dr. Jack Cornett Director Radiation Protection Bureau Health Canada

RESEARCH GRANTS AND CONTRACTS

NSERC Research Grant    Metal speciation and bioavailability in freshwaters	2002-2005
NSERC Research Network    Metals In The Environment-Research Network (MITE-RN)	1999-2004
Networks of Centres of Excellence    The Canadian Water Network (CWN)	2001-2007
Nickel Producers Environmental Research Association, USA, Research Contract    A new chemical technology for measuring speciation in freshwaters and in atmospheric precipitation	1998-2003
Inco Limited, Research Contract	1998-2003
Falconbridge Ltd., Research Contract	1998-2003

Varian Canada Inc., sponsor of the 
Varian Canada - Carleton University Laboratory for Ultratrace Analysis Research

Brinkmann Instruments (Canada), Ltd.

Nickel Producers Environmental Research Association, USA

Inco Limited

Falconbridge Ltd.

LINKS

CSC 2004, London, ON, Canada, June 1 - 5, 2002 
87th Canadian Society for Chemistry Conference and Exhibition 

Featuring a Special Symposium organized by C.L. Chakrabarti  
Biogeochemistry of Metals in the Environment

NATIONAL CENTRE OF EXCELLENCE 
Canadian Water Network (CWN)

Faculty News -- This is Carleton 

NSERC RESEARCH NETWORK
Metals In The Environment - Research Network (MITE-RN)


Fredriks Research Products
The source for Laurentian Humic and Fulvic Acid


Advanced Micro Devices, Inc. (AMD)