Gary Curtis (Former Employee)
Science and Products
Filter Total Items: 27
Bioremediation in fractured rock: 1. Modeling to inform design, monitoring, and expectations Bioremediation in fractured rock: 1. Modeling to inform design, monitoring, and expectations
Field characterization of a trichloroethene (TCE) source area in fractured mudstones produced a detailed understanding of the geology, contaminant distribution in fractures and the rock matrix, and hydraulic and transport properties. Groundwater flow and chemical transport modeling that synthesized the field characterization information proved critical for designing bioremediation of the...
Authors
Claire Tiedeman, Allen Shapiro, Paul Hsieh, Thomas Imbrigiotta, Daniel Goode, Pierre Lacombe, Mary DeFlaun, Scott Drew, Carole Johnson, John Williams, Gary Curtis
Bioremediation in fractured rock: 2. Mobilization of chloroethene compounds from the rock matrix Bioremediation in fractured rock: 2. Mobilization of chloroethene compounds from the rock matrix
A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre- and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site...
Authors
Allen Shapiro, Claire Tiedeman, Thomas Imbrigiotta, Daniel Goode, Paul Hsieh, Pierre Lacombe, Mary DeFlaun, Scott Drew, Gary Curtis
Extent and persistence of secondary water quality impacts after enhanced reductive bioremediation Extent and persistence of secondary water quality impacts after enhanced reductive bioremediation
Electron donor (ED) addition can be very effective in stimulating enhanced reductive bioremediation (ERB) of a wide variety of groundwater contaminants. However, ERB can result in Secondary Water Quality Impacts (SWQIs) including decreased levels of dissolved oxygen (O2), nitrate (NO3- ), and sulfate (SO42- ), and elevated levels of dissolved manganese (Mn2+), dissolved iron (Fe2+)...
Authors
Robert Borden, Jason Tillotson, Gene-Hua Ng, Barbara Bekins, Douglas Kent, Gary Curtis
Upscaling of U (VI) desorption and transport from decimeter‐scale heterogeneity to plume‐scale modeling Upscaling of U (VI) desorption and transport from decimeter‐scale heterogeneity to plume‐scale modeling
Scientifically defensible predictions of field scale U(VI) transport in groundwater requires an understanding of key processes at multiple scales. These scales range from smaller than the sediment grain scale (less than 10 μm) to as large as the field scale which can extend over several kilometers. The key processes that need to be considered include both geochemical reactions in...
Authors
Gary Curtis, Matthias Kohler, Ramakrishnan Kannappan, Martin Briggs, Frederick Day-Lewis
Maximum likelihood Bayesian model averaging and its predictive analysis for groundwater reactive transport models Maximum likelihood Bayesian model averaging and its predictive analysis for groundwater reactive transport models
While Bayesian model averaging (BMA) has been widely used in groundwater modeling, it is infrequently applied to groundwater reactive transport modeling because of multiple sources of uncertainty in the coupled hydrogeochemical processes and because of the long execution time of each model run. To resolve these problems, this study analyzed different levels of uncertainty in a...
Authors
Gary Curtis, Dan Lu, Ming Ye
A computer program for uncertainty analysis integrating regression and Bayesian methods A computer program for uncertainty analysis integrating regression and Bayesian methods
This work develops a new functionality in UCODE_2014 to evaluate Bayesian credible intervals using the Markov Chain Monte Carlo (MCMC) method. The MCMC capability in UCODE_2014 is based on the FORTRAN version of the differential evolution adaptive Metropolis (DREAM) algorithm of Vrugt et al. (2009), which estimates the posterior probability density function of model parameters in high...
Authors
Dan Lu, Ming Ye, Mary Hill, Eileen Poeter, Gary Curtis
Assessment of parametric uncertainty for groundwater reactive transport modeling, Assessment of parametric uncertainty for groundwater reactive transport modeling,
The validity of using Gaussian assumptions for model residuals in uncertainty quantification of a groundwater reactive transport model was evaluated in this study. Least squares regression methods explicitly assume Gaussian residuals, and the assumption leads to Gaussian likelihood functions, model parameters, and model predictions. While the Bayesian methods do not explicitly require...
Authors
Xiaoqing Shi, Ming Ye, Gary Curtis, Geoffery Miller, Philip Meyer, Matthias Kohler, Steve Yabusaki, Jichun Wu
Effects of error covariance structure on estimation of model averaging weights and predictive performance Effects of error covariance structure on estimation of model averaging weights and predictive performance
When conducting model averaging for assessing groundwater conceptual model uncertainty, the averaging weights are often evaluated using model selection criteria such as AIC, AICc, BIC, and KIC (Akaike Information Criterion, Corrected Akaike Information Criterion, Bayesian Information Criterion, and Kashyap Information Criterion, respectively). However, this method often leads to an...
Authors
Dan Lu, Ming Ye, Philip D. Meyer, Gary Curtis, Xiaoqing Shi, Xu-Feng Niu, Steve Yabusaki
Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II) Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II)
Production of elemental mercury, Hg(0), via Hg(II) reduction is an important pathway that should be considered when studying Hg fate in environment. We conducted a kinetic study of abiotic homogeneous and surface-catalyzed Hg(0) production by Fe(II) under dark anoxic conditions. Hg(0) production rate, from initial 50 pM Hg(II) concentration, increased with increasing pH (5.5–8.1) and...
Authors
Aria Amirbahman, Douglas Kent, Gary Curtis, Mark Marvin-DiPasquale
Simultaneous estimation of local-scale and flow path-scale dual-domain mass transfer parameters using geoelectrical monitoring Simultaneous estimation of local-scale and flow path-scale dual-domain mass transfer parameters using geoelectrical monitoring
Anomalous solute transport, modeled as rate-limited mass transfer, has an observable geoelectrical signature that can be exploited to infer the controlling parameters. Previous experiments indicate the combination of time-lapse geoelectrical and fluid conductivity measurements collected during ionic tracer experiments provides valuable insight into the exchange of solute between mobile...
Authors
Martin A. Briggs, Frederick Day-Lewis, John Ong, Gary Curtis, John Lane
Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity
Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita...
Authors
Troy Brosten, Frederick Day-Lewis, Gregory Schultz, Gary Curtis, John Lane
Comparing approaches for simulating the reactive transport of U(VI) in ground water Comparing approaches for simulating the reactive transport of U(VI) in ground water
The reactive transport of U(VI) in a well-characterized shallow alluvial aquifer at a former U(VI) mill located near Naturita, CO, was predicted for comparative purposes using a surface complexation model (SCM) and a constant K d approach to simulate U(VI) adsorption. The ground water at the site had U(VI) concentrations that ranged from 0.01 to 20 µM, alkalinities that ranged from 2.5...
Authors
G.P. Curtis, M. Kohler, J.A. Davis
Science and Products
Filter Total Items: 27
Bioremediation in fractured rock: 1. Modeling to inform design, monitoring, and expectations Bioremediation in fractured rock: 1. Modeling to inform design, monitoring, and expectations
Field characterization of a trichloroethene (TCE) source area in fractured mudstones produced a detailed understanding of the geology, contaminant distribution in fractures and the rock matrix, and hydraulic and transport properties. Groundwater flow and chemical transport modeling that synthesized the field characterization information proved critical for designing bioremediation of the...
Authors
Claire Tiedeman, Allen Shapiro, Paul Hsieh, Thomas Imbrigiotta, Daniel Goode, Pierre Lacombe, Mary DeFlaun, Scott Drew, Carole Johnson, John Williams, Gary Curtis
Bioremediation in fractured rock: 2. Mobilization of chloroethene compounds from the rock matrix Bioremediation in fractured rock: 2. Mobilization of chloroethene compounds from the rock matrix
A mass balance is formulated to evaluate the mobilization of chlorinated ethene compounds (CE) from the rock matrix of a fractured mudstone aquifer under pre- and postbioremediation conditions. The analysis relies on a sparse number of monitoring locations and is constrained by a detailed description of the groundwater flow regime. Groundwater flow modeling developed under the site...
Authors
Allen Shapiro, Claire Tiedeman, Thomas Imbrigiotta, Daniel Goode, Paul Hsieh, Pierre Lacombe, Mary DeFlaun, Scott Drew, Gary Curtis
Extent and persistence of secondary water quality impacts after enhanced reductive bioremediation Extent and persistence of secondary water quality impacts after enhanced reductive bioremediation
Electron donor (ED) addition can be very effective in stimulating enhanced reductive bioremediation (ERB) of a wide variety of groundwater contaminants. However, ERB can result in Secondary Water Quality Impacts (SWQIs) including decreased levels of dissolved oxygen (O2), nitrate (NO3- ), and sulfate (SO42- ), and elevated levels of dissolved manganese (Mn2+), dissolved iron (Fe2+)...
Authors
Robert Borden, Jason Tillotson, Gene-Hua Ng, Barbara Bekins, Douglas Kent, Gary Curtis
Upscaling of U (VI) desorption and transport from decimeter‐scale heterogeneity to plume‐scale modeling Upscaling of U (VI) desorption and transport from decimeter‐scale heterogeneity to plume‐scale modeling
Scientifically defensible predictions of field scale U(VI) transport in groundwater requires an understanding of key processes at multiple scales. These scales range from smaller than the sediment grain scale (less than 10 μm) to as large as the field scale which can extend over several kilometers. The key processes that need to be considered include both geochemical reactions in...
Authors
Gary Curtis, Matthias Kohler, Ramakrishnan Kannappan, Martin Briggs, Frederick Day-Lewis
Maximum likelihood Bayesian model averaging and its predictive analysis for groundwater reactive transport models Maximum likelihood Bayesian model averaging and its predictive analysis for groundwater reactive transport models
While Bayesian model averaging (BMA) has been widely used in groundwater modeling, it is infrequently applied to groundwater reactive transport modeling because of multiple sources of uncertainty in the coupled hydrogeochemical processes and because of the long execution time of each model run. To resolve these problems, this study analyzed different levels of uncertainty in a...
Authors
Gary Curtis, Dan Lu, Ming Ye
A computer program for uncertainty analysis integrating regression and Bayesian methods A computer program for uncertainty analysis integrating regression and Bayesian methods
This work develops a new functionality in UCODE_2014 to evaluate Bayesian credible intervals using the Markov Chain Monte Carlo (MCMC) method. The MCMC capability in UCODE_2014 is based on the FORTRAN version of the differential evolution adaptive Metropolis (DREAM) algorithm of Vrugt et al. (2009), which estimates the posterior probability density function of model parameters in high...
Authors
Dan Lu, Ming Ye, Mary Hill, Eileen Poeter, Gary Curtis
Assessment of parametric uncertainty for groundwater reactive transport modeling, Assessment of parametric uncertainty for groundwater reactive transport modeling,
The validity of using Gaussian assumptions for model residuals in uncertainty quantification of a groundwater reactive transport model was evaluated in this study. Least squares regression methods explicitly assume Gaussian residuals, and the assumption leads to Gaussian likelihood functions, model parameters, and model predictions. While the Bayesian methods do not explicitly require...
Authors
Xiaoqing Shi, Ming Ye, Gary Curtis, Geoffery Miller, Philip Meyer, Matthias Kohler, Steve Yabusaki, Jichun Wu
Effects of error covariance structure on estimation of model averaging weights and predictive performance Effects of error covariance structure on estimation of model averaging weights and predictive performance
When conducting model averaging for assessing groundwater conceptual model uncertainty, the averaging weights are often evaluated using model selection criteria such as AIC, AICc, BIC, and KIC (Akaike Information Criterion, Corrected Akaike Information Criterion, Bayesian Information Criterion, and Kashyap Information Criterion, respectively). However, this method often leads to an...
Authors
Dan Lu, Ming Ye, Philip D. Meyer, Gary Curtis, Xiaoqing Shi, Xu-Feng Niu, Steve Yabusaki
Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II) Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II)
Production of elemental mercury, Hg(0), via Hg(II) reduction is an important pathway that should be considered when studying Hg fate in environment. We conducted a kinetic study of abiotic homogeneous and surface-catalyzed Hg(0) production by Fe(II) under dark anoxic conditions. Hg(0) production rate, from initial 50 pM Hg(II) concentration, increased with increasing pH (5.5–8.1) and...
Authors
Aria Amirbahman, Douglas Kent, Gary Curtis, Mark Marvin-DiPasquale
Simultaneous estimation of local-scale and flow path-scale dual-domain mass transfer parameters using geoelectrical monitoring Simultaneous estimation of local-scale and flow path-scale dual-domain mass transfer parameters using geoelectrical monitoring
Anomalous solute transport, modeled as rate-limited mass transfer, has an observable geoelectrical signature that can be exploited to infer the controlling parameters. Previous experiments indicate the combination of time-lapse geoelectrical and fluid conductivity measurements collected during ionic tracer experiments provides valuable insight into the exchange of solute between mobile...
Authors
Martin A. Briggs, Frederick Day-Lewis, John Ong, Gary Curtis, John Lane
Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity Inversion of multi-frequency electromagnetic induction data for 3D characterization of hydraulic conductivity
Electromagnetic induction (EMI) instruments provide rapid, noninvasive, and spatially dense data for characterization of soil and groundwater properties. Data from multi-frequency EMI tools can be inverted to provide quantitative electrical conductivity estimates as a function of depth. In this study, multi-frequency EMI data collected across an abandoned uranium mill site near Naturita...
Authors
Troy Brosten, Frederick Day-Lewis, Gregory Schultz, Gary Curtis, John Lane
Comparing approaches for simulating the reactive transport of U(VI) in ground water Comparing approaches for simulating the reactive transport of U(VI) in ground water
The reactive transport of U(VI) in a well-characterized shallow alluvial aquifer at a former U(VI) mill located near Naturita, CO, was predicted for comparative purposes using a surface complexation model (SCM) and a constant K d approach to simulate U(VI) adsorption. The ground water at the site had U(VI) concentrations that ranged from 0.01 to 20 µM, alkalinities that ranged from 2.5...
Authors
G.P. Curtis, M. Kohler, J.A. Davis