Education:

B.S. Agriculture 1961 University of Arizona
M.S. Soil Physics 1963 University of Arizona
Ph.D. Soil Science 1965 University of California at Berkeley

Teaching:

Professor Sposito teaches courses on physical chemistry 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, Introduction to Environmental Studies, with English professor Robert Hass.

Research:

Aqueous geochemistry, especially coordination chemistry, surface chemistry, and colloidal behavior; mathematical models of geochemical and mass transport processes in porous media; molecular simulations of geochemical systems.

Selected Publications:

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.
Sposito, G. 2001. Methods of quantum field theory in the physics of subsurface solute transport. Transp. Porous Media 42:181.
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. Miner. 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.
Bourg, I. C., G. Sposito, and A. C. M. Bourg. 2006. Tracer diffusion in compacted water-saturated bentonite. Clays Clay Miner. 54:363.
Sutton, R. and G. Sposito. 2006. Molecular simulation of humic substance-Ca-montmorillonite complexes. Geochim. Cosmochim. Acta 70:3566.
Peretyazhko, T. and G. Sposito. 2006. Reducing capacity of terrestrial humic acids. Geoderma 137:140.
Lo, W.-C., G. Sposito, and E. Majer. 2007. Low-frequency dilatational wave propagation through unsaturated porous media containing two immiscible fluids. Transport Porous Media 68:91.
Bourg, I. C., G. Sposito, and A. C. M. Bourg. 2007. Modeling the acid-base surface chemistry of montmorillonite. J. Colloid Interface Sci. 312:297.
Duckworth, O. W. and G. Sposito. 2007. Siderophore-promoted dissolution of synthetic and biogenic layer type Mn oxides. Chem. Geol. 242:500.
Bourg, I. C. and G. Sposito. 2007. Molecular dynamics simulations of kinetic isotope fractionation during the diffusion of ionic species in water. Geochim. Cosmochim. Acta 71:5583.
Bourg, I. C., G. Sposito, and A. C. M. Bourg. 2007. Modeling cation diffusion in compacted water-saturated sodium bentonite at low ionic strength. Environ. Sci. Technol. 41:8118.
Peña, J., O. W. Duckworth, J. R. Bargar, and G. Sposito. 2007. Dissolution of hausmannite (Mn3O4) in the presence of the trihydroxamate siderophore desferrioxamine B. Geochim. Cosmochim. Acta 71:5661.
Sposito, G. 2008. Geochemistry in Soil Science. In W. Chesworth (ed.), Encyclopedia of Soil Science. Springer, New York.
Sposito, G. 2008. The Chemistry of Soils. 2nd Ed. Oxford University Press, New York.

Awards:

Senior Fulbright Lecturer (University of Córdoba)
Guggenheim Fellow (University of Oxford)
Fellow: American Geophysical Union, American Society of Agronomy, European Association of Geochemistry, Geochemical Society, International Union of Pure and Applied Chemistry, and Soil Science Society of America
Soil Science Research Award, Soil Science Society of America
Hydrology Section Research Award, American Geophysical Union
Distinguished Teaching Award, Sonoma State University
Distinguished Teaching Award, University of California at Riverside
Miller Research Professor, University of California at Berkeley
Foreign Member, Academy of Agriculture of France
"Landmark" Paper Award, Assocation of Environmental Engineering and Science Professors
Walter J. Weber, Jr. Distinguished Lecture in Environmental Sciences and Engineering, University of Michigan
Highly-cited Researcher, Ecology and Environment, Institute for Scientific Information
Horton Medal, American Geophysical Union

Service:

Associate Editor: Advances in Water Resources, Geochimica et Cosmochimica Acta, Geoderma, Sciences Géologiques, Topics in Environmental Chemistry (Oxford University Press)

Research Projects:

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. These remarkable earth materials are discussed more fully in G. Sposito, "Soil," Encyclopaedia Britannica Online.
Much of the chemical behavior of soils and sediments is driven by microorganisms, particularly bacteria and fungi. Iron biogeochemical cycling, for example, is influenced by Fe(III)-reducing bacteria that utilize humus as "electron shuttles." Microbially-produced Mn oxides can adsorb metals and promote the degradation of organic compounds. These two examples illustrate the close relationship between geochemistry and microbiology in soil environments.

Current Projects:

• Structure and reactivity of biogenic manganese oxides
• Geochemistry of arsenic in groundwater
• Iron bioreduction mechanisms in soils
• Chemodynamics of antibiotics in aquatic systems

Research in aqueous geochemistry has long benefited from insights provided by molecular simulations. The underlying philosophy of these simulations is to construct a mathematical description of molecular interactions, then solve the resulting equations for a system of molecules in order to predict its properties. These simulations are critical to a fundamental understanding of the surface and colloid chemistry of natural nanoparticles.
A description of current research projects is given on our simulations web site at Lawrence Berkeley National Laboratory.
A central problem in theoretical, subsurface hydrology is the detailed mathematical description of water flow through porous media. One approach to this problem is the continuum theory of mixtures, which provides a rigorous method for describing multiphase systems, such as unsaturated soils, from a strictly macroscopic viewpoint. Another approach 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. This description is especially apt for investigating chaotic advection by fluids.

Current Projects:

• Acoustic wave propagation through unsaturated soils
• Chaotic solute advection by groundwater flow