Mechanisms and dynamics of abiotic and biotic interations at Environmental Interfaces (Rosso EMSI-Stanford, PNNL Scope # 47286).
EMSL Project ID
12296
Abstract
I. STANFORD EMSI SCIENCE OVERVIEWThe main scientific focus of the Stanford EMSI is on chemical and microbiological interactions at solid-aqueous solution interfaces of relevance to Earth?s near-surface environment where natural waters, natural organic matter, and biological organisms interact with natural solids and environmental contaminants. Surface chemical processes are of vital environmental concern because they control the chemical weathering of minerals, corrosion, the development of soils, water quality, colloid stability, contaminant and nutrient sequestration and release, soil rheological properties, acid mine drainage, the respiratory cycle of microorganisms, and the biogeochemical cycling of elements. The Stanford EMSI brings a unique, multi-faceted approach to address the complex interactions of aqueous inorganic species and microbial organisms with solid surfaces at the molecular level.
Three major goals of the EMSI are: 1) Gain a molecular-level understanding of the structure of the electrical double layer at metal oxide-aqueous interfaces as a function of solid structure and properties (e.g., different bulk structures, dielectric constants, pHpzc, and solubilities) and solution conditions (e.g., pH, ionic strength, metal and ligand concentrations), 2) Understand how common microbial organisms interact with mineral surfaces and common contaminant ions and how the resulting microbial biofilms affect the properties of and processes occurring at the solid-aqueous solution interface, and 3) Understand the mechanisms by which biofilms attach to environmental solids.
The EMSI will investigate the interactions of environmentally abundant and reactive mineral surfaces (Al-, Fe-, and Mn-oxides, metal-sulfides, phosphates, and silicates), with water and common heavy metal and metalloid contaminant ions (e.g., Cr(III,VI), Ni(II), Cu(II), Zn(II), As(III,V), Se(IV,VI), Rb(I), Sr(II), Cd(II), Pb(II), U(VI)) and common soil bacteria (e.g., Burkholderia cepacia, Shewanella oneidensis MR-1, Caulobacter crescentus, Bacillus subtilis, Methanospirillum hungatei, Synechocystis sp., Thiobacillus sp.). To handle this complexity, we will employ a reductionist approach in which we first carry out coupled experimental and theoretical studies of interfacial processes in simplified model systems, where system variables can be carefully controlled. This will be followed by studies of increasingly complex model systems, ultimately approaching the complexity of natural systems.
Primary techniques to be used include synchrotron radiation-based spectroscopy (?-XAFS, grazingincidence XAFS, x-ray standing wave, x-ray photoelectron and emission, non-resonant x-ray Raman), scattering (x-ray reflectivity, crystal truncation rod diffraction), and micro-imaging (scanning transmission x-ray microscopy, micro-fluorescence mapping), modern computational chemistry (density functional theory, ab initio thermodynamics, ab initio molecular dynamics), and molecular genomics. The EMSI will also employ a variety of non-synchrotron methods (STM, AFM, TEM, ultra-fast UV-visible (and XAFS) spectroscopy, high-resolution SEM) at Stanford University, the Molecular Foundry at LBNL, and the Environmental Molecular Science Laboratory (EMSL) at PNNL.
The complexity of chemical and microbial processes taking place at environmental interfaces dictates a collaborative, interdisciplinary approach. The EMSI team is a collaboration of researchers from three different academic institutions (Stanford, Princeton, Alaska-Fairbanks), two DOE national laboratories (PNNL, LBNL), and the NIST. The team brings relevant expertise in aqueous and surface geochemistry (Brown, Myneni, Rosso, Trainor), biomineralization (Brown, Spormann), computational chemistry (Chaka, Rosso), molecular microbiology (Spormann), physical chemistry (Bergmann, Gaffney, Toney), soil chemistry (Fendorf), and surface chemistry and physics (Bluhm, Nilsson, Salmeron). This team also has expertise in relevant in situ surface-sensitive synchrotron techniques and in scanning tunneling and atomic force microscopy.
The PNNL contribution to the Stanford EMSI is two-pronged, in both cases involving the resources of the EMSL, a DOE-OBER sponsored national user facility at PNNL. First, molecular modeling resources and expertise will be applied to various scientific questions in the EMSI, with an emphasis on electron transfer (ET) reactions. Second, experimental instrumentation not available at other institutions in the EMSI will be made available to EMSI researchers. Kevin Rosso is the scientific point of contact for both the molecular modeling and ambient AFM/STM resources of the Environmental Spectroscopy and Biogeochemistry facility of the EMSL.
Project Details
Project type
Exploratory Research
Start Date
2004-12-03
End Date
2007-06-07
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members