My research focuses on the chemical speciation of trace elements in aqueous systems at the earth's surface and in the subsurface. Trace elements such as the transition metals lead, cadmium, copper and zinc, the lanthanide or 'rare earth' elements, and actinide elements such as uranium, occur naturally in most geologic systems but at fairly low concentrations. In ore deposits or as a result of anthropogenic contamination, these elements can be elevated to unusually high, and often toxic, concentrations. Understanding the processes that control the chemical speciation of these elements is a high priority. Trace element chemical speciation can be governed by a variety of factors, including water composition, pH, the presence of minerals and mineral surfaces, and the activity of bacteria. Microorganisms can profoundly influence geochemistry, but in ways that are not fully understood at present. In my research group, we try to understand what controls trace element behavior in natural geologic systems, using a combination of field and laboratory investigations. Lab work focuses on experimental studies that provide fundamental properties for governing reactions, such as microbial redox catalysis, surface complexation and coordination reactions, and mineral precipitation phenomena.

Educational Background

Ph.D. - Washington University at St. Louis, 1993
B.Sc. - Auburn University, 1988

Research Specializations

Microbial biogeochemistry - the interaction of bacteria, fungi, and algae with minerals and aqueous species, biosorption and biomineralization of trace elements,  and redox influences of microbes on trace element speciation and solubility.

Surface-aqueous interface geochemistry- adsorption of trace elements by minerals and biomass, surface complexation theory.

Thermodynamic modeling- aqueous speciation of ions in solution, solubility of metal-organic and inorganic complexes, numerical modeling and prediction of chemical thermodynamic properties.

Ongoing Projects

Understanding the relationship between the chemical speciation of uranium and its availability to microbial dissimilatory reduction.

Investigating experimentally the chemical equilibria governing competitive oxyligand adsorption onto mineral surfaces.

Determining experimentally the chemical surface properties of natural, synthetic and biogenic uranium oxide (UO2), with particular emphasis on establishing the surface charge behavior and propensity for metal adsorption onto UO2 surfaces.

Courses Taught

GEOS 2000 - Evolution of Life
GEOS 5550 - Introduction to Geochemistry
ENVS 2150 - Environmental Systems and Cycles
CHEM 5400 - Biogeochemistry

Selected Publications [5]

Haas J. R. and Northup A. (2004) Effects of aqueous complexation on reductive precipitation of uranium by Shewanella putrefaciens. Geochemical Transactions 5(3), 41-48.

Haas J. R. (2004) Effects of cultivation conditions on acid-base titration properties of Shewanella putrefaciens. Chemical Geology 209, 67-81.

Haas J. R. and DiChristina T. J. (2002) Effects of Fe(III) chemical speciation on dissimilatory Fe(III) reduction by Shewanella putrefaciens. Environmental Science and Technology 36, 373-380.

Haas J. R., DiChristina T. J., and R. Wade J. (2001) Thermodynamics of U(VI) sorption onto Shewanella putrefaciens. Chemical Geology 180, 33-54.

Haas J. R. and Shock E. L. (1999) Halocarbons in the environment: Estimates of thermodynamic properties for aqueous chloroethylene species and their stabilities in natural settings. Geochimica et Cosmochimica Acta 63(19/20), 3429-3441.

Haas J. R., Bailey E. H., and Purvis O. W. (1998) Bioaccumulation of metals by lichens: Uptake of aqueous uranium by Peltigera membranacea as a function of time and pH. American Mineralogist 83(11-12, Part 2), 1494-1502.