GEOBIOLOGICAL SURFACE CHEMISTRY

How does the Earth's environment change because of interactions between natural waters, minerals and rocks, and living organisms?

These interactions occur at interfaces. Although much is known about the chemistry of water and minerals separately, and the biochemistry of organisms, the chemical interactions between them mediated by interfaces are poorly understood.

For example, there is no quantitative basis for prediction of how these interfaces behave. Understanding the combined water-electrolyte-mineral-biomolecule interface, involving both inorganic and organic species, is the key to the geochemical cycling of many chemical elements including metals and nutrient species. It is the foundation of a quantitative understanding of a wide variety of geochemical and biogeochemical processes including weathering and soil formation, life in the oceans, the migration of toxic species in the environment, the binding of medical implants in the human body, and theories about the origin of life.

A major goal of my research is to place our understanding of the water-electrolyte-mineral-biomolecule interface on a predictive basis. This involves an integration of inorganic and organic chemistry and biochemistry with physical chemistry and crystal chemistry.

Together with my former undergraduate, graduate, and postdoctoral students, I have developed a progressively more comprehensive quantitative basis for prediction of the behavior of the surface chemistry of minerals in water. Starting with the adsorption on mineral surfaces of aqueous protons, then 1:1 electrolytes, 2:1 electrolytes, and most recently 1:2 electrolytes, we have built a quantitative basis for assessing the behavior of the mineral-water interface for the inorganic constituents of most natural water compositions. This is now being further developed to include elevated temperatures, the migration of toxic species such as As(III) and As(V), and the role of interfacial reactions in the geochemical cycling of the rare earth elements.

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