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
Groundwater recharge and agricultural contamination
Denitrification in the recharge area and discharge area of a transient agricultural nitrate plume in a glacial outwash sand aquifer, Minnesota
Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents
Isotope-abundance variations of selected elements (IUPAC technical report)
Selected field and analytical methods and analytical results in the Dutch Flats area, western Nebraska, 1995-99
A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater
Groundwater residence times in Shenandoah National Park, Blue Ridge Mountains, Virginia, USA: A multi-tracer approach
Timescales for nitrate contamination of spring waters, northern Florida, USA
Interaction of surface water and ground water in the Dutch Flats area, western Nebraska, 1995-99
Determining timescales for groundwater flow and solute transport
Groundwater/surface-water interactions and sources of nitrogen and uranium in an irrigated area of Nebraska, USA
Effects of topography and soil properties on recharge at two sites in an agricultural field
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
Groundwater recharge and agricultural contamination
Denitrification in the recharge area and discharge area of a transient agricultural nitrate plume in a glacial outwash sand aquifer, Minnesota
Compilation of minimum and maximum isotope ratios of selected elements in naturally occurring terrestrial materials and reagents
Isotope-abundance variations of selected elements (IUPAC technical report)
Selected field and analytical methods and analytical results in the Dutch Flats area, western Nebraska, 1995-99
A bacterial method for the nitrogen isotopic analysis of nitrate in seawater and freshwater
Groundwater residence times in Shenandoah National Park, Blue Ridge Mountains, Virginia, USA: A multi-tracer approach
Timescales for nitrate contamination of spring waters, northern Florida, USA
Interaction of surface water and ground water in the Dutch Flats area, western Nebraska, 1995-99
Determining timescales for groundwater flow and solute transport
Groundwater/surface-water interactions and sources of nitrogen and uranium in an irrigated area of Nebraska, USA
Effects of topography and soil properties on recharge at two sites in an agricultural field
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.