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
Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms
Interlaboratory comparison of reference materials for nitrogen-isotope-ratio measurements
Effect of ground-water/surface-water interactions on nitrate concentrations in discharge from the South Platte River alluvial aquifer, Colorado
Geologic, hydrothermal, and biologic studies at Escanaba Trough, Gorda Ridge, offshore northern California
Chemical analyses of ground and surface water from Battle Brook drainage basin, near Princeton, Minnesota
Radium isotope geochemistry of thermal waters, Yellowstone National Park, Wyoming, USA
New reference materials for nitrogen-isotope-ratio measurements
Chemical, isotopic, and microbiological evidence for denitrification during transport of domestic wastewater through a thick unsaturated zone in the Mojave Desert, San Bernardino County, California
Reporting of nitrogen-isotope abundances (Technical Report)
Laser microprobe analyses of Cl, Br, I, and K in fluid inclusions: Implications for sources of salinity in some ancient hydrothermal fluids
Laser microprobe analyses of noble gas isotopes and halogens in fluid inclusions: Analyses of microstandards and synthetic inclusions in quartz
Brine history indicated by argon, krypton, chlorine, bromine, and iodine analyses of fluid inclusions from the Mississippi Valley type lead-fluorite-barite deposits at Hansonburg, New Mexico
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
Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms
Interlaboratory comparison of reference materials for nitrogen-isotope-ratio measurements
Effect of ground-water/surface-water interactions on nitrate concentrations in discharge from the South Platte River alluvial aquifer, Colorado
Geologic, hydrothermal, and biologic studies at Escanaba Trough, Gorda Ridge, offshore northern California
Chemical analyses of ground and surface water from Battle Brook drainage basin, near Princeton, Minnesota
Radium isotope geochemistry of thermal waters, Yellowstone National Park, Wyoming, USA
New reference materials for nitrogen-isotope-ratio measurements
Chemical, isotopic, and microbiological evidence for denitrification during transport of domestic wastewater through a thick unsaturated zone in the Mojave Desert, San Bernardino County, California
Reporting of nitrogen-isotope abundances (Technical Report)
Laser microprobe analyses of Cl, Br, I, and K in fluid inclusions: Implications for sources of salinity in some ancient hydrothermal fluids
Laser microprobe analyses of noble gas isotopes and halogens in fluid inclusions: Analyses of microstandards and synthetic inclusions in quartz
Brine history indicated by argon, krypton, chlorine, bromine, and iodine analyses of fluid inclusions from the Mississippi Valley type lead-fluorite-barite deposits at Hansonburg, New Mexico
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.