Garrison Sposito

Professor
Ph.D.  Soil Science    University of California at Berkeley, 1965
B.S.   Agriculture    University of Arizona, 1961

117B Hilgard Hall
Berkeley, California 94720
gsposito@nature.berkeley.edu
office: 510-643-8297   lab: 510-643-8297   fax:  510-643-2940

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Professor Sposito teaches courses on aqueous geochemistry as applied to terrestrial ecosystems, particularly in soils and aquifers, including an undergraduate course on environmental geochemistry and a graduate course on the surface and colloid chemistry of natural particles. His research interests involve coordination chemistry, surface chemistry, and colloidal behavior; mathematical models of transport processes in porous media; and the computer simulation of natural aqueous systems.

Professor Sposito teaches courses on physical chemistry as applied to natural aqueous systems, particularly soils and aquifers, including an undergraduate course on environmental aqueous geochemistry and a graduate course on the surface and colloid chemistry of natural particles. He also teaches an undergraduate course on environmental studies with Professor Robert Hass.

From the point of view of chemistry, soils are open, multicomponent, biogeochemical systems containing solids, liquids, and gases. That they are open systems means soils exchange both matter and energy with the surrounding atmosphere, biosphere, and hydrosphere. These flows of matter and energy to or from soils are highly variable in time and space, but they are the essential fluxes that cause the development of soil profiles and govern the patterns of soil quality.

Most of the chemical behavior of soils and sediments is driven by microorganisms, particularly bacteria and fungi. Iron cycling, for example, is influenced by microbially-produced compounds, called siderophores, which have a very high affinity for Fe(III). These compounds affect the cycling of other metals through complexes they form with them, thus raising the possibility of their use in environmental remediation. Similar possibilities exist for microbially-produced Mn oxides, whose surfaces can promote the degradation of organic compounds, including pesticides. These examples illustrate the close relationship between geochemistry and microbiology in natural environments. Current projects include experimental and theoretical studies of siderophore reactions, the structure and reactivity of biogenic manganese oxides, iron oxidation-reduction reactions in tropical soils, and arsenic biogeochemistry in aquifers.

Research on molecular behavior in aqueous systems has long benefited from insights provided by Monte Carlo, molecular dynamics, and ab initio quantum mechanical simulations. The underlying philosophy of these simulations is to construct a mathematical description of molecular interactions, then sample the configuration of a system of molecules in order to ascertain its properties. Recent molecular simulations of interlayer structure in clays have provided realistic modeling of ion-water-clay mineral interactions. These interactions are critical to a fundamental understanding of experimental measurements in the surface and colloid chemistry of natural nanoparticles. Current projects involve ab initio calculations of mineral structures using density functional theory, as well as molecular models of ion diffusion in aqueous media and antibiotic reactions with soil humus.

A central problem in subsurface hydrology is the detailed mathematical description of water flow through a heterogeneous porous formation. One useful approach to this problem is the continuum theory of mixtures, which provides a rigorous method for describing multiphase systems from a strictly macroscopic viewpoint. Another rigorous approach to obtaining a more general model of water flow in natural porous media is based on the theory of dynamical systems. A dynamical system describes how moving spatial points flow under the influence of a velocity field, usually by means of an ordinary differential equation featuring time as the independent variable ("Lagrangian approach"). The questions posed and settled are "global" in character, applicable to a broad class of flows. Current topics under investigation include chaotic advection of solutes in groundwater and wave propagation through porous media in which immiscible fluids are flowing.

Derrendinger, L., and G. Sposito. 2000. Flocculation kinetics and cluster morphology in illite/NaCl suspensions. J. Colloid Interface Sci. 222:1.

Park, S.-H., and G. Sposito. 2000. Monte Carlo simulation of total radial distribution functions for interlayer water in Li-, Na-, and K-montmorillonite hydrates. J. Phys. Chem. B104:4642.

Greathouse, J.A., K. Refson, and G. Sposito. 2000. Molecular dynamics simulation of water mobility in magnesium-smectite hydrates. J. Am. Chem. Soc. 46:11459.

Dubbin, W.E., G. Sposito, and M. Zavarin. 2000. X-ray absorption spectroscopic study of Cu-glyphosate adsorbed by microcrystalline gibbsite. Soil Sci. 165:699.

Martin-Neto, L., D.G. Traghetta, C.M.P. Vaz, S. Crestana, and G. Sposito. 2001. On the interaction mechanisms of atrazine and hydroxyatrazine with humic substances. J. Environ. Qual. 30:250.

Sposito, G. 2001. Topological groundwater hydrodynamics. Advan. Water Resour. 24:793.

Sutton, R., and G. Sposito. 2001. Molecular simulation of interlayer structure and dynamics in 12.4 Å Cs-smectite hydrates. J. Colloid Interface Sci. 237:174.

Struyk, Z., and G. Sposito. 2001. Redox properties of standard humic acids. Geoderma 102:329.

Cocozza, C., C.C.G. Tsao, S.-F. Cheah, S.M. Kraemer, K.N. Raymond, T.M. Miano, and G. Sposito. 2002. Temperature dependence of goethite dissolution promoted by trihydroxamate siderophores. Geochim. Cosmochim. Acta 66:431.

Kraemer, S.M., J. Xu, K.N. Raymond, and G. Sposito. 2002. Adsorption of Pb(II) and Eu(III) by oxide minerals in the presence of natural and synthetic hydroxamate siderophores. Environ. Sci. Technol. 36:1287.

Park, S.-H., and G. Sposito. 2002. Structure of water adsorbed on a mica surface. Phys. Rev. Lett. 89:85501.

Lo, W.-C., G. Sposito, and E.L. Majer. 2002. Immiscible two-phase fluid flows in deformable porous media. Advan. Water Resour. 25:1105.

Sutton, R., and G. Sposito. 2002. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers. Geochem. Trans. 3:73.

Manceau, A., N. Tamura, M. A. Marcus, A. A. MacDowell,, R. S. Celestre, R. E. Sublett, G. Sposito and H. A. Padmore. 2002. Deciphering Ni sequestration in soil ferromanganese nodules by combining X-ray fluorescence, absorption, and diffraction at micrometer scales of resolution. Amer. Mineralogist 87:1494.

Manceau, A., N. Tamura, R. S. Celestre, A. A. MacDowell, N. Geoffroy, G. Sposito, and H. A. Padmore. 2003. Molecular-scale speciation of Zn and Ni in soil ferromanganese nodules from loess soils of the Mississippi Basin. Environ. Sci. Technol. 37:75.

Cheah, S.-F., S. M. Kraemer, J. Cervini-Silva, and G. Sposito. 2003. Steady-state dissolution kinetics of goethite in the presence of desferrioxamine B and oxalate ligands: Implications for microbial acquisition of iron. Chem. Geol. 198:63.

Park, S.-H. and G. Sposito. 2003. Do montmorillonite surfaces promote methane hydrate formation? J. Phys. Chem. B 107:2281.

Villalobos, M., B. Toner, J. Bargar, and G. Sposito. 2003. Characterization of the manganese oxide produced by Pseudomonas putida strain MnB1. Geochim. Cosmochim. Acta 67:2649.

Refson, K., S.-H. Park, and G. Sposito. 2003. Ab initio computational crystallography of 2:1 clay minerals: 1. Pyrophyllite-1Tc. J. Phys. Chem. B 107:13,376.

Bourg, I.C., A.C.M. Bourg, and G. Sposito. 2003. Modeling diffusion and adsorption in compacted bentonite: A critical review. J. Contam. Hydrol. 61:293.

Sposito, G. 2004. The Surface Chemistry of Natural Particles. Oxford University Press, New York. 242 p.

Park, S.-H. and G. Sposito. 2004. Molecular modeling of clay structure and surface chemistry. In S.A. Auerbach, K.A. Carrado, and P.K. Dutta (eds.), Handbook of Layered Materials Science & Technology, Chap. 2. Marcel Dekker, New York.

Sposito, G. 2004. Scaling of Soil Physical Properties and Processes. In D. Hillel (ed.), Encyclopedia of Soils in the Environment, pp. 472-476. Elsevier, San Diego.

Parker, D.L., G. Sposito, and B.M. Tebo. 2004. Manganese (III) binding to a pyoverdine siderophore produced by a manganese (II)-oxidizing bacterium. Geochim. Cosmochim. Acta 68:4809.

Toner, B.M., S. Fakra, M. Villalobos, T. Warwick, and G. Sposito. 2005. Spatially resolved characterization of biogenic manganese oxide production within a bacterial biofilm. Appl. Environ. Microbiol. 71:1300.

Villalobos, M., J. Bargar, and G. Sposito. 2005. Mechanisms of Pb(II) sorption on a biogenic manganese oxide. Environ. Sci Technol. 39:569.

Lo, W.-C., G. Sposito, and E. Majer. 2005. Wave propagation through elastic porous media containing two immiscible fluids. Water Resour. Res. 41(2):W02025 (20pp.).

Toner, B., and G. Sposito. 2005. Reductive dissolution of biogenic manganese oxides in the presence of a hydrated biofilm. Geomicrobiol. J. 22:171.

Dubbin, W.E. and G. Sposito. 2005. Copper-glyphosate sorption to microcrystalline gibbsite in the presence of soluble Keggin Al13 polymers. Environ. Sci Technol. 39:2509.

Sutton, R., G. Sposito, M.S. Diallo, and H.-R. Schulten. 2005. Molecular simulation of a model of dissolved organic matter. Environ. Toxicol. Chem. 24: 1902.

Peretyazhko, T. and G. Sposito. 2005. Iron(III) reduction and phosphorus solubilization in humid tropical forest soils. Geochim. Cosmochim. Acta 69:3643.

Duckworth, O.W. and G. Sposito. 2005. Siderophore-manganese(III) interactions. I. Air-oxidation of manganese(II) promoted by Desferrioxamine B. Environ. Sci. Technol. 69:6037.

Duckworth, O.W. and G. Sposito. 2005. Siderophore-manganese(III) interactions. II. Manganite dissolution promoted by Desferrioxamine B. Environ. Sci. Technol. 69:6045.

Toner, B., A. Manceau, M. A. Marcus, D. B. Millet, and G. Sposito. 2005. Zinc sorption by a bacterial biofilm. Environ. Sci. Technol. 39:8288.

Sutton, R. and G. Sposito. 2005. Molecular structure in soil humic substances: The new view. Environ. Sci. Technol. 39:9009.

Villalobos, M., J. Bargar, and G. Sposito. 2005. Trace metal retention on biogenic manganese oxide nanoparticles. Elements 1:223.

Lo, W.-C., G. Sposito, and E. Majer. 2006. Low-frequency dilatational wave propagation through fully-saturated porous media. Advan. Water Resour. 29:408.

Sposito, G. 2006. Chaotic solute advection by unsteady groundwater flow. Water Resour. Res. 42:W06D03, doi:10.1029/2005WR004518 (6 pp.).

Toner, B., A. Manceau, S. M. Webb, and G. Sposito. 2006. Zinc sorption by biogenic hexagonal birnessite particles within a hydrated biofilm. Geochim. Cosmochim. Acta 70:27.

Villalobos, M., B. Lanson, A. Manceau, B. Toner, and G. Sposito. 2006. Structural model for the biogenic Mn oxide produced by Pseudomonas putida. Am. Miner. 91:489.