John Karl Bohlke, PhD
Dr. John Karl Bohlke is a Scientist Emeritus affiliated with the Earth Systems Processes Division and the Reston Stable Isotope Laboratory of the USGS Water Resources Mission Area.
Dr. John Karl (JK) Bohlke retired as a Senior Research Scientist and currently serves as a Scientist Emeritus affiliated with the Earth System Processes Division and the Reston Stable Isotope Laboratory of the Water Mission Area. During his career with USGS, he has studied processes related to both mineral resources and water resources. His published work includes field and laboratory-based studies of water-rock interactions, geochronology, and chemical transport in diverse hydrogeologic settings. Recent activities include development of stable isotopic methods and applications in hydrology and biogeochemistry, use of isotopes and environmental tracers to determine transport and reaction rates in groundwater and surface water, and multidisciplinary investigations of contaminant origin and migration. Selected priority topics related to water quality include excess nutrients and inorganic contaminants, effects of agriculture and wastewater disposal practices, watershed responses to land use change, groundwater/surface water interactions, and environmental forensics.
Professional Experience
Hydrologist, National Research Program and Earth System Processes Division, Water Mission Area, US Geological Survey, Reston, Virginia (since 1991)
Geologist, Eastern Mineral Resources, US Geological Survey, Reston, Virginia
Postdoc (Geoscience), Argonne National Laboratory, Chicago, Illinois
Geologist, Western Mineral Resources, US Geological Survey, Menlo Park, California
Cartographer, US Soil Conservation Service, Hyattsville, Maryland
Education and Certifications
PhD (Geology and Geophysics), University of California, Berkeley, California
MS (Marine Geology), Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Florida
BS (Geology), University of Michigan, Ann Arbor, Michigan
Science and Products
Erratum to: Isotopic composition and origin of indigenous natural perchlorate and co-occurring nitrate in the southwestern United States
Natural chlorate in the environment: Application of a new IC-ESI/MS/MS method with a Cl18O3- internal standard
Isotopic composition and origin of indigenous natural perchlorate and co-occurring nitrate in the southwestern United States
Mixing effects on apparent reaction rates and isotope fractionation during denitrification in a heterogeneous aquifer
Comprehensive inter-laboratory calibration of reference materials for δ18O versus VSMOW using various on-line high-temperature conversion techniques
Errata: Atomic weights of the elements: Review 2000
Atacama perchlorate as an agricultural contaminant in groundwater: Isotopic and chronologic evidence from Long Island, New York
Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes
Contrasting residence times and fluxes of water and sulfate in two small forested watersheds in Virginia, USA
Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA
Biogeochemistry at a wetland sediment-alluvial aquifer interface in a landfill leachate plume
Fractionation of stable isotopes in perchlorate and nitrate during in situ biodegradation in a sandy aquifer
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
Science and Products
Erratum to: Isotopic composition and origin of indigenous natural perchlorate and co-occurring nitrate in the southwestern United States
Natural chlorate in the environment: Application of a new IC-ESI/MS/MS method with a Cl18O3- internal standard
Isotopic composition and origin of indigenous natural perchlorate and co-occurring nitrate in the southwestern United States
Mixing effects on apparent reaction rates and isotope fractionation during denitrification in a heterogeneous aquifer
Comprehensive inter-laboratory calibration of reference materials for δ18O versus VSMOW using various on-line high-temperature conversion techniques
Errata: Atomic weights of the elements: Review 2000
Atacama perchlorate as an agricultural contaminant in groundwater: Isotopic and chronologic evidence from Long Island, New York
Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes
Contrasting residence times and fluxes of water and sulfate in two small forested watersheds in Virginia, USA
Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA
Biogeochemistry at a wetland sediment-alluvial aquifer interface in a landfill leachate plume
Fractionation of stable isotopes in perchlorate and nitrate during in situ biodegradation in a sandy aquifer
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.