Sparks

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Soils: “…the most complicated biomaterials on the planet..." (Young, 2004)

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The root-soil interface The microbe-mineral interface It’s About Interfaces!

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ms s min h d mo yr mil Time Scale Ion Association Multivalent Ion Hydrolysis Gas-Water Ion Exchange Sorption Mineral Solution Mineral Crystallization

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Waterfall plot of a 1-hr experiment tracking As oxidation at the RSB surface at pH = 7.0. The main peak of interest is the arsenate peak at ~818 cm-1. The data were collected at 1-minute time intervals.

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Contour diagrams from infrared mapping obtained at the end of the experiment showing the spatial distribution of the infrared absorption peaks corresponding to (top) Mycobacterium sp. JLS bacteria, (middle) ESHA, and (bottom) pyrene. Appropriate spectral regions were integrated for each point on the maps. The center of the map shows a region with high density of bacteria and high concentration of ESHA where pyrene has been completely degraded. From Holman et. al., (2002).

Comparison of FTIR and MO/DFT Results: 

Comparison of FTIR and MO/DFT Results C3v (3 bands)=monodentate * Paul et al., High Surface Loading, pH 4 Comparison of experimental ATR-FTIR frequencies (cm-1) of sulfate adsorbed to α-Fe2O3 and theoretical vibrational frequencies (cm-1, UB3LYP/6-31G+(d)) C2v (4 bands)=bidentate bridging Experimental* Theoretical Sulfate Bisulfate

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Complex Rhizospheric Interactions ROOT Biotic interface ROOT ROOT PGPRs; Symbionts Biocontrol, VAM, endophytes Growth facilitators Type-III Phytotoxins Antibacterial compounds, QS mimics Antifungal compounds Allelopathy Vectors for symbioses, SARs Phytotoxins Nematicidal compounds Root herbivory Abiotic interface Heavy metal toxicity AERIAL Parts Root secretion and metal speciation

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Micro Scanning X-ray Fluorescence (m-SXRF) Beamline 10.3.2 ALS LBNL, Berkeley, CA Ni Ni Mn Ni Mn Ca 50mm 50mm 50mm 50mm 50mm m-XAFS

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Fine root cross-section Stem cross-section Leaf cross-section Ni Ni Mn Ca Fe Zn Zn A Whole Plant Picture of Metal Partitioning

Soil Physical-Chemical-Biological Research Frontiers: 

Soil Physical-Chemical-Biological Research Frontiers Effect of coupled hydrobiogeochemical processes on contaminant and nutrient transport Transport and sorption kinetics and mechanisms of contaminants on nanoparticles Real-time studies on interfacial reaction mechanisms and transformations using molecular scale techniques (synchrotron-based and in-situ nanoscale techniques such as biologic force microscopy BFM)

Soil Physical-Chemical-Biological Research Frontiers: 

Soil Physical-Chemical-Biological Research Frontiers Effect of biofilms on natural surfaces and impacts on physical/chemical/biological reaction mechanisms Role of biogenically derived minerals on contaminated transport and solubility Coupling of molecular modeling and molecular scale studies Plant/soil interfacial reactions

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A New Initiative to Understand Soils and Earth's Weathering Engine

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Nutrients Chemistry of Water Atmosphere Landform Evolution What processes control fluxes of carbon, particulates, and reactive gases over different timescales? How do biogeochemical processes govern long-term sustainability of water and soil resources? How do processes that nourish ecosystems change over human and geologic time scales? How do variations in and perturbation to chemical and physical weathering processes impact the Critical Zone? The Four Driving Questions

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Biology Geology The Challenge: Critical Zone Science Crosses Disciplines and Scales Anderson et al., 2004; Chorover, J. (unpub.) Soil Science

A Network of Tools: 

A Network of Tools Cosmogenic isotopes allow dating of exposure surfaces New isotopes and other tracers can document biological cycling, age of comminution, rates of dissolution near equilibrium Environmental imaging tools are available for soil observatories New molecular biological techniques allow the investigation of geobiological phenomena New nanoscale spectroscopies allow investigation of chemistry of mineral-soil-water-biota interface Environmental sensors are becoming available for investigating field sites