Bachelor's Degree(s): University of Concordia, 1992
PhD: University of Calgary, 1997
PostDoc: Nova Chemicals, 1998-2000; University of Calgary
Area of Interest
We take a holistic approach to the study of environmental chemistry, with a special focus on humic materials. Natural organic matter (NOM) is the largest pool of active carbon on our planet while humic materials constitute the largest fraction of NOM. Humic materials also form indispensable couplings between the atmosphere, lithosphere, hydrosphere, and biosphere. They are major role players in the transport, deposition, speciation, and bioavailability of organic and inorganic compounds of both natural and xenobiotic origins. Hence, they play a major role in determining the health and fertility of an ecosystem. They have also been directly and indirectly linked to human health. Consequently, similar to how a fundamental understanding of proteins is essential in the understanding of the human body, a fundamental knowledge of humic materials is critical in the understanding of the ecosystem known as Earth.
To this end our research focuses on studying interactions of inorganic (mainly metal ions) and organic compounds (mainly estrogen mimicking compounds, agricultural pharmaceuticals, agricultural chemicals, and other xenobiotic compounds of environmental concern) with humic materials, and how humic materials behave in the environment at a molecular level.
Because, humic materials are complex heterogeneous polydisperse mixtures whose properties are echoed in their structural diversity, state of aggregation, conformation, and surface charge distribution, high resolution techniques are needed to study them in the detail we wish to. Also, unlike for biochemical compounds, isotopic labeling is not possible. Thus, a combination of techniques such as state of the art high resolution 1D and 2D solid and liquid state NMR, FT-ICR-MS, and fluorescence will be used. Some recent work by us to establish the feasibility of studying humic materials at a molecular level, akin to that of proteins, is presented in figures 1 and 2.
Several research projects are being initiated in our group to address the issues discussed and are very briefly summarized below.
Studying How Organic and Inorganic Compounds Interact with Humic Materials at a Molecular Level
This project applies advanced analytical methods to study how organic and inorganic pollutants of environmental and toxicological concern interact with humic materials on a molecular level, similar to the study of drug interactions and delivery in biomedical research. By utilizing this approach we hope to obtain a better understanding of the transport and fate of toxic pollutants in the environment, with the long-term goal of being able to model the bioavailabilty of toxic compounds in the "real world". The analytical methods that will be used in this research will be state of the art single and multi-dimensional nuclear magnetic resonance (NMR), Fourier transform ion cyclotron resonance mass spectroscopy (FT-ICR-MS), light scattering, fluorescence and other appropriate cutting edge techniques as they emerge.
Figure 1: A 1H,1H TOCSY spectra of the reference humic material known as Laurentian fulvic acid obtained on the Bruker Avance 500 spectrometer at the BioNMR Centre, University of Calgary, Calgary, Canada
Figure 2: A 1H,13C HMBC spectra of the reference humic material known as Laurentian fulvic acid obtained on the Bruker Avance 500 spectrometer at the BioNMR Centre, University of Calgary, Calgary, Canada
Speciation of Humic Materials in the Environment
In this project, the speciation of humic materials in the ecosystem as whole will be studied. Humic materials from both terrestrial (farmlands, pastures, fields, forests, the shores of rivers, lakes, swamps, and estuaries, as well as abandoned industrial sites) and aquatic (lakes, ponds, wetlands, rivers, and estuaries) components of the ecosystem will be isolated. The isolated humic materials will then be characterized by advanced high resolution techniques as discussed above. The goal of this project is to obtain a better understanding of how humic materials are speciated and transported in the environment at a molecular level, and thus a better understanding of the fate, transport, and distribution of inorganic and organic pollutants in the ecosystem.
How Humic Materials Interact with Membranes via Advanced Analytical Methods
Membranes are one of nature’s most powerful defenses against toxic compounds. Recently it has been shown that humic materials can make a cell membrane more permeable to organic compounds, thus severely weakening this defense. However, the mechanism by which this takes place is unknown. In this research area we will monitor and understand the effect NOM has on model membranes in terms of their permeability towards both organic and inorganic toxins found in the environment, and hence their bioavalablity. To address these complex issues, advanced, state of the art, single and multi-dimensional NMR, fluorescence, and FT infrared methods will be used to monitor the membrane, humic materials, and toxic compounds.
Development of Field Monitoring Techniques for Humic Materials Based on Data from Advanced Analytical Methods
Recognizing that advanced, state of the art techniques are expensive, non- portable and hence inappropriate for field research, a development of parallel field monitoring methods is essential. Field measurements allow us to monitor the "real world" and hence the true fate of compounds of environmental and toxicological importance, especially their bioavailability. Thus, the goal of this research is to develop better field monitoring techniques based on the molecular level studies discussed in project 1 (see above). This will be accomplished by first finding relationships or correlations between what is observed at the molecular level (measured by the advanced high-resolution techniques) and what can be observed by methods that are suitable for field work such as fluorescence and low resolution mass spectroscopy.
Modeling Soil Uptake of Xenobiotic Compounds
In a terrestrial environment one must consider more than just humic materials when modeling the uptake of pollutants. In this project a soil system would be broken down into its basic components and each will be studied separately, particularly in how it uptakes xenobiotic compounds. Subsequently, these different fractions will be combined in different ways and their collective uptake xenobiotic compounds will be studied. The goal of this research will be to study how soils uptake xenobiotic compounds at a molecular level. Once again NMR will be a very important method along with X-ray diffraction, I.R., and electron microscopy.
Molecular Level Studies of Siderophores Interact with Humic Materials
The sequestering of iron is one of the most difficult and challenging aspects of life. Many bacteria have found a solution in the form of an extremely strongly iron binding family of molecules known as siderophores. Although these molecules are essential to life, as we know it on our planet, little is known what happens to siderophores from the time they are secreted to the time they are reacquired by the bacteria. Due to their nature, humic materials should play a major role in the fate of siderophores in the environment. This research project will study how siderophores interact with humic materials by a combination of analytical techniques including NMR and mass spectroscopy.
It should also be noted that many of the humic substances studied will be collected locally. Thus most of the projects mentioned above are very amenable to field work.
The long term goals of this research is to gain an understanding of humic materials at a molecular level and in doing so allow us to avoid damaging the ecosystem known as earth.