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Johnson R. Haas |
Courses Taught ENVS 2150 - Environmental Systems and Cycles GEOS 2000 - Evolution of Life, A Geologic Perspective GEOS 5550 - Introduction to Geochemistry |
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Research Aqueous Geochemistry, Microbe-Mineral Interactions, Geochemistry of Radionuclides 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. |
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Ongoing Projects • Experimental measurement of heavy metal adsorption onto mineral and bacterial surfaces, coordinative properties of mineral and bacterial surfaces. • Geochemical influences on microbial redox transformations of uranium. |
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Recent Publications Haas J. R. and Purvis O. W. (2006) Lichen biogeochemistry, in Fungi in Biogeochemical Cycles, G. M. Gadd, ed. Cambridge University Press, 490 p. 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. |
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Department of Geosciences
1187 Rood Hall
1903 West Michigan Ave
Kalamazoo, MI 49008
Phone: (269) 387-5485
Fax: (269) 387-5513
mohamed.sultan@wmich.edu
Any questions concerning the website should be directed to: johnson.haas@wmich.edu
©2007 Department of Geosciences, WMU