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RESEARCH STATEMENT - Using the foundations of organic chemistry, inorganic chemistry, physical chemistry, and the nanosciences, my students and I explore natural biogeochemical phenomena and properties/transformations of synthetic chemicals in environmental media. Our focus is on the impact of speciation. Knowing protonation level and modes of coordination makes it possible to predict transformations (e.g. oxidation, reduction, nucleophilic substitution/addition), partitioning (sorption, volatilization) and mass transport. - Our geochemical investigations are focused on biochemicals released by plants, bacteria, and fungi into surrounding environmental media. Some facilitate nutrient uptake (e.g. siderophores), some are used for communication (e.g. quorum-sensing compounds), and some interfere with the activities of other organisms (antibiotics, quorum-quenching chemicals, allelochemicals). Ultimately, extracellular biochemicals undergo alteration and incorporation into natural organic matter (NOM), a complex mixture of chemicals that play many important biogeochemical roles. - We're also interested in engineered systems and the consequences of human activities. Synthetic chemicals directly added to environmental media merit special attention, i.e. chemicals used in agriculture, animal production, forestry, and aquaculture. Large volumes of water are used for cooling, paper-making, and water supply. We're interested in how the natural constituents found in such waters interact with treatment chemicals. - My students and I have been studying chemical reactions at nanoparticle/water interfaces for more than 25 years. In one recent study, we explored how biochemicals found in biofluids (blood, sweat, tears, mucus) reduce and dissolve nano-sized manganese dioxide and lead dioxide particles in suspension. Information from our laboratory experiments may assist in understanding the health affects of exposure to hydrous oxide nanoparticles.
Research Interests
- Chemical kinetics and mechanisms of environmental reactions
- Abiotic degradation of inorganic and organic pollutants
- Metal ion speciation in natural and engineered systems
- Oxidation-reduction and nucleophile-electrophile reactions, homogeneous and heterogeneous
- Aqueous chemistry of quorum-sensing chemicals, quorum-quenching chemicals, natural antibiotics, allelochemicals, and other extracellular biochemicals
- Agriculture, aquaculture, and biogeochemistry
- Chelating agents and other hydrophilic compounds in environmental media
- Coordination chemistry: thermodynamics and kinetics
- Heterogeneous chemistry of soils, sediments and aquifers
- Toxic metal ion and radionuclide subsurface chemistry and transport
- Nanoscale reactions at the surfaces of oxide/hydroxides and other minerals
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