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
Deposition, accumulation, and alteration of Cl−, NO3−, ClO4− and ClO3− salts in a hyper-arid polar environment: Mass balance and isotopic constraints
Anoxic nitrate reduction coupled with iron oxidation and attenuation of dissolved arsenic and phosphate in a sand and gravel aquifer
Relating carbon and nitrogen isotope effects to reaction mechanisms during aerobic or anaerobic degradation of RDX (Hexahydro-1,3,5-Trinitro-1,3,5-Triazine) by pure bacterial cultures
A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells
Corrigendum to “Widespread occurrence of (per)chlorate in the Solar System” [Earth Planet. Sci. Lett. 430 (2015) 470–476]
Identification of groundwater nitrate contamination from explosives used in road construction: Isotopic, chemical, and hydrologic evidence
Widespread occurrence of (per)chlorate in the Solar System
Role of anaerobic ammonium oxidation (anammox) in nitrogen removal from a freshwater aquifer
Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments
Chemical considerations for an updated National assessment of brackish groundwater resources
Tracing the cycling and fate of the explosive 2,4,6-trinitrotoluene in coastal marine systems with a stable isotopic tracer, 15N-[TNT]
Groundwater movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)
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
Deposition, accumulation, and alteration of Cl−, NO3−, ClO4− and ClO3− salts in a hyper-arid polar environment: Mass balance and isotopic constraints
Anoxic nitrate reduction coupled with iron oxidation and attenuation of dissolved arsenic and phosphate in a sand and gravel aquifer
Relating carbon and nitrogen isotope effects to reaction mechanisms during aerobic or anaerobic degradation of RDX (Hexahydro-1,3,5-Trinitro-1,3,5-Triazine) by pure bacterial cultures
A partial exponential lumped parameter model to evaluate groundwater age distributions and nitrate trends in long-screened wells
Corrigendum to “Widespread occurrence of (per)chlorate in the Solar System” [Earth Planet. Sci. Lett. 430 (2015) 470–476]
Identification of groundwater nitrate contamination from explosives used in road construction: Isotopic, chemical, and hydrologic evidence
Widespread occurrence of (per)chlorate in the Solar System
Role of anaerobic ammonium oxidation (anammox) in nitrogen removal from a freshwater aquifer
Global patterns and environmental controls of perchlorate and nitrate co-occurrence in arid and semi-arid environments
Chemical considerations for an updated National assessment of brackish groundwater resources
Tracing the cycling and fate of the explosive 2,4,6-trinitrotoluene in coastal marine systems with a stable isotopic tracer, 15N-[TNT]
Groundwater movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)
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.