A5075412717- Radioactive element chemistry and processing
- Groundwater flow and contamination studies
- Mine drainage and remediation techniques
- Clay minerals and soil interactions
- Groundwater and Isotope Geochemistry
- Hydrology and Watershed Management Studies
- Geochemistry and Elemental Analysis
- Soil Carbon and Nitrogen Dynamics
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Seismic Waves and Analysis
- Earthquake Detection and Analysis
- Soil and Unsaturated Flow
- Arsenic contamination and mitigation
- Heavy metals in environment
- Radioactive contamination and transfer
- Soil and Water Nutrient Dynamics
- Iron oxide chemistry and applications
- Geochemistry and Geologic Mapping
- Cryospheric studies and observations
- Atmospheric and Environmental Gas Dynamics
- Analytical chemistry methods development
- Fire effects on ecosystems
- Environmental remediation with nanomaterials
- Hydrocarbon exploration and reservoir analysis
University of Arizona
2015-2024
Brigham Young University
2023
University of Nevada, Reno
2023
Arizona Science Center
2018
Oregon State University
2016
Pennsylvania State University
1995-2011
Lawrence Berkeley National Laboratory
2010
United States Geological Survey
2009
University of Hawaiʻi at Mānoa
2009
University of Hawaii System
2009
Abstract Tree species can influence biogeochemistry through variation in the quantity and chemistry of their litter, associated impacts on soil heterotrophic community. However, role that different plant traits play these processes is not well understood, nor it clear whether effects soils largely reflect a gymnosperm vs. angiosperm contrast. Using replicated, long‐term monoculture plot experiment, we examined among 14 tree 30 years after establishment, assessed litter vis‐à‐vis such...
Reactions at ionizable functional groups in extracellular polymeric substances (EPS) from Bacillus subtilis are found to affect aqueous phase conformation and adsorption mineral surfaces. Characterization by HPSEC, XPS, FTIR indicates a wide range apparent molecular mass (0.57−128 kDa), with group composition depending on cell growth (exponential vs stationary) location suspension (free cell-bound). ATR-FTIR spectroscopy shows complexation dissociation of protons acidic that result α-helical...
The contribution of various bacterial surface functional groups to adhesion at hematite and ZnSe surfaces was examined using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy. When live Shewanella oneidensis, Pseudomonas aeruginosa, Bacillus subtilis cells were introduced a horizontal (α-Fe2O3)-coated internal reflection element (IRE), FTIR peaks emerged corresponding phosphate group binding. These IR not observed when bacteria the uncoated IRE. added...
Abstract Soils retain large quantities of carbon, thereby slowing its return to the atmosphere. The mechanisms governing organic carbon sequestration in soil remain poorly understood, yet are integral understanding soil‐climate feedbacks. We evaluated biochemistry dissolved and solid potential source sink horizons across a chronosequence volcanic soils Hawai'i. derived from similar basaltic parent material on gently sloping shield surfaces, support same vegetation assemblage, exhibit strong...
Hydrology is an integrative discipline linking the broad array of water-related research with physical, ecological, and social sciences. The increasing breadth hydrological research, often where subdisciplines hydrology partner related sciences, reflects central importance water to environmental science, while highlighting fractured nature itself. This lack coordination among hydrologic has hindered development theory integrated models capable predicting partitioning across time space....
Abstract Decomposition of soil organic matter (SOM) can be stimulated by fresh input, a phenomenon known as the ‘priming effect’. Despite its global importance, relationship priming effect to mineral weathering and nutrient release remains unclear. Here we show close linkages between in critical zone primed decomposition SOM. Intensified rock-derived are generally coupled with SOM resulting from “triggered” microbial activity. Fluxes products decomposed via linearly correlated congruency....
Abstract Forest soils, rather than woody biomass, are the dominant long‐term sink for N in forest fertilization studies and, by inference, from atmospheric deposition. Recent evidence of significant abiotic immobilization inorganic‐N humus layers challenges a previously widely held view that microbial processes pathways soil. Understanding plant, microbial, and mechanisms soils has important implications understanding current future carbon budgets. Abiotic nitrate is particularly perplexing...
Cesium adsorption on the clay minerals vermiculite and montmorillonite is described as a function of surface coverage using extended X-ray fine structure spectroscopy (EXAFS). (Cs) possessed variable coordination environment consisting Cs−O distances between 3.2 4.3 Å; however, disorder typical Cs environments prevented resolution all oxygen shells. On basis influence loading exchange ability this structural arrangement, we could recognize both inner-sphere outer-sphere complexes. The...
Research Article| October 01, 2007 Soil Biogeochemical Processes within the Critical Zone Jon Chorover; Chorover 1Department of Soil, Water and Environmental Science University Arizona, Tucson, AZ 85721, USA E-mail: chorover@cals.arizona.edu Search for other works by this author on: GSW Google Scholar Ruben Kretzschmar; Kretzschmar 2Institute Biogeochemistry Pollutant Dynamics Department Sciences ETH Zurich, CHN, CH-8092 Switzerland kretzschmar@env.ethz.ch Ferran Garcia-Pichel; Garcia-Pichel...
Environmental contextPerfluoroalkyl compounds are organic contaminants that exhibit strong resistance to chemical- and microbial-degradation. As partitioning between solid aqueous phases is expected control the transport of perfluoroalkyl compounds, we studied molecular mechanisms their adsorption–desorption at a representative Fe oxide surface using in situ spectroscopy. The results provide valuable information on types bonds formed, enable better understanding fate these natural...
In redox-dynamic soils, iron reduction−oxidation events may initiate wide shifts in the concentration of colloidal and dissolved material because either Fe mineral dissolution or pH associated with oxidation state changes. This can have profound effects on mobilization organic metal constituents. We conducted laboratory studies colloid dynamics a Hawaiian soil subjected to four consecutive 14-day cycles across "soil-Fe" (Fe(OH)3)/(Fe2+(aq)) equilibrium. Size fractionated samples were...
Rising atmospheric CO2 concentrations have increased interest in the potential for forest ecosystems and soils to act as carbon (C) sinks. While soil organic C contents often vary with tree species identity, little is known about if, how, influence stability of soil. Using a 40 year old common garden experiment replicated plots eleven temperate species, we investigated relationships between matter (SOM) mineral 17 ecological factors (including tissue chemistry, magnitude inputs their...
Abstract. The critical zone (CZ), the dynamic living skin of Earth, extends from top vegetative canopy through soil and down to fresh bedrock bottom groundwater. All humans live in depend on CZ. This has three co-evolving surfaces: canopy, ground surface, a deep subsurface below which Earth's materials are unweathered. network nine CZ observatories supported by US National Science Foundation made advances broad areas research relating surfaces. First, monitoring revealed how natural...