Christopher T Green, Ph.D.
Christopher Green is a Research Hydrologist with the USGS Water Resources Mission Area.
Research Interests
- Flow and reactive transport in complex geological media
- Nitrogen cycling and fluxes in groundwater in agricultural areas
- Flow and solute transport in the unsaturated zone
- Gas transport in the unsaturated zone
- Effects of biofuels crops on groundwater quality
Science and Products
Filter Total Items: 52
Unsaturated zone CO2, CH4, and δ13C-CO2 at an arid region low-level radioactive waste disposal site Unsaturated zone CO2, CH4, and δ13C-CO2 at an arid region low-level radioactive waste disposal site
Elevated tritium, radiocarbon, Hg, and volatile organic compounds associated with low-level radioactive waste (LLRW) at the USGS Amargosa Desert Research Site (ADRS) have stimulated research on factors and processes that affect contaminant gas distribution and transport. Consequently, we examined the sources, mixing, and biogeochemistry of CO2 and CH4, two additional important species in...
Authors
Christopher H. Conaway, Michelle Ann Walvoord, Randall B. Thomas, Christopher Green, R.J. Baker, James J. Thordsen, David A. Stonestrom, Brian J. Andraski
Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA
Nitrate contamination of groundwater in agricultural areas poses a major challenge to the sustainability of water resources. Aquifer vulnerability models are useful tools that can help resource managers identify areas of concern, but quantifying nitrogen (N) inputs in such models is challenging, especially at large spatial scales. We sought to improve regional nitrate (NO3−) input...
Authors
Bernard T. Nolan, Christopher T. Green, Paul F. Juckem, Lixia Liao, James E. Reddy
Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA
Process-based modeling of regional NO3− fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3− reactive transport processes make implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3− in the vadose zone and groundwater. The regional VFM was applied...
Authors
Christopher T. Green, Lixia Liao, Bernard T. Nolan, Paul F. Juckem, Christopher L. Shope, Anthony J. Tesoriero, Bryant C. Jurgens
Comparison of time nonlocal transport models for characterizing non-Fickian transport: From mathematical interpretation to laboratory application Comparison of time nonlocal transport models for characterizing non-Fickian transport: From mathematical interpretation to laboratory application
Non-Fickian diffusion has been increasingly documented in hydrology and modeled by promising time nonlocal transport models. While previous studies showed that most of the time nonlocal models are identical with correlated parameters, fundamental challenges remain in real-world applications regarding model selection and parameter definition. This study compared three popular time...
Authors
Bingqing Lu, Yong Zhang, Chunmiao Zheng, Christopher T. Green, Charles O’Neill, Hong-Guang Sun, Jiazhong Qian
Bounded fractional diffusion in geological media: Definition and Lagrangian approximation Bounded fractional diffusion in geological media: Definition and Lagrangian approximation
Spatiotemporal Fractional-Derivative Models (FDMs) have been increasingly used to simulate non-Fickian diffusion, but methods have not been available to define boundary conditions for FDMs in bounded domains. This study defines boundary conditions and then develops a Lagrangian solver to approximate bounded, one-dimensional fractional diffusion. Both the zero-value and non-zero-value...
Authors
Yong Zhang, Christopher T. Green, Eric M. LaBolle, Roseanna M. Neupauer, Hong-Guang Sun
Regional oxygen reduction and denitrification rates in groundwater from multi-model residence time distributions, San Joaquin Valley, USA Regional oxygen reduction and denitrification rates in groundwater from multi-model residence time distributions, San Joaquin Valley, USA
Rates of oxygen and nitrate reduction are key factors in determining the chemical evolution of groundwater. Little is known about how these rates vary and covary in regional groundwater settings, as few studies have focused on regional datasets with multiple tracers and methods of analysis that account for effects of mixed residence times on apparent reaction rates. This study provides...
Authors
Christopher T. Green, Bryant C. Jurgens, Yong Zhang, Jeffrey Starn, Michael J. Singleton, Bradley K. Esser
Science and Products
Filter Total Items: 52
Unsaturated zone CO2, CH4, and δ13C-CO2 at an arid region low-level radioactive waste disposal site Unsaturated zone CO2, CH4, and δ13C-CO2 at an arid region low-level radioactive waste disposal site
Elevated tritium, radiocarbon, Hg, and volatile organic compounds associated with low-level radioactive waste (LLRW) at the USGS Amargosa Desert Research Site (ADRS) have stimulated research on factors and processes that affect contaminant gas distribution and transport. Consequently, we examined the sources, mixing, and biogeochemistry of CO2 and CH4, two additional important species in...
Authors
Christopher H. Conaway, Michelle Ann Walvoord, Randall B. Thomas, Christopher Green, R.J. Baker, James J. Thordsen, David A. Stonestrom, Brian J. Andraski
Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA Metamodeling and mapping of nitrate flux in the unsaturated zone and groundwater, Wisconsin, USA
Nitrate contamination of groundwater in agricultural areas poses a major challenge to the sustainability of water resources. Aquifer vulnerability models are useful tools that can help resource managers identify areas of concern, but quantifying nitrogen (N) inputs in such models is challenging, especially at large spatial scales. We sought to improve regional nitrate (NO3−) input...
Authors
Bernard T. Nolan, Christopher T. Green, Paul F. Juckem, Lixia Liao, James E. Reddy
Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA Regional variability of nitrate fluxes in the unsaturated zone and groundwater, Wisconsin, USA
Process-based modeling of regional NO3− fluxes to groundwater is critical for understanding and managing water quality, but the complexity of NO3− reactive transport processes make implementation a challenge. This study introduces a regional vertical flux method (VFM) for efficient estimation of reactive transport of NO3− in the vadose zone and groundwater. The regional VFM was applied...
Authors
Christopher T. Green, Lixia Liao, Bernard T. Nolan, Paul F. Juckem, Christopher L. Shope, Anthony J. Tesoriero, Bryant C. Jurgens
Comparison of time nonlocal transport models for characterizing non-Fickian transport: From mathematical interpretation to laboratory application Comparison of time nonlocal transport models for characterizing non-Fickian transport: From mathematical interpretation to laboratory application
Non-Fickian diffusion has been increasingly documented in hydrology and modeled by promising time nonlocal transport models. While previous studies showed that most of the time nonlocal models are identical with correlated parameters, fundamental challenges remain in real-world applications regarding model selection and parameter definition. This study compared three popular time...
Authors
Bingqing Lu, Yong Zhang, Chunmiao Zheng, Christopher T. Green, Charles O’Neill, Hong-Guang Sun, Jiazhong Qian
Bounded fractional diffusion in geological media: Definition and Lagrangian approximation Bounded fractional diffusion in geological media: Definition and Lagrangian approximation
Spatiotemporal Fractional-Derivative Models (FDMs) have been increasingly used to simulate non-Fickian diffusion, but methods have not been available to define boundary conditions for FDMs in bounded domains. This study defines boundary conditions and then develops a Lagrangian solver to approximate bounded, one-dimensional fractional diffusion. Both the zero-value and non-zero-value...
Authors
Yong Zhang, Christopher T. Green, Eric M. LaBolle, Roseanna M. Neupauer, Hong-Guang Sun
Regional oxygen reduction and denitrification rates in groundwater from multi-model residence time distributions, San Joaquin Valley, USA Regional oxygen reduction and denitrification rates in groundwater from multi-model residence time distributions, San Joaquin Valley, USA
Rates of oxygen and nitrate reduction are key factors in determining the chemical evolution of groundwater. Little is known about how these rates vary and covary in regional groundwater settings, as few studies have focused on regional datasets with multiple tracers and methods of analysis that account for effects of mixed residence times on apparent reaction rates. This study provides...
Authors
Christopher T. Green, Bryant C. Jurgens, Yong Zhang, Jeffrey Starn, Michael J. Singleton, Bradley K. Esser