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 movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)
Evaluation of perchlorate sources in the Rialto-Colton and Chino California subbasins using chlorine and oxygen isotope ratio analysis
Educational webtool illustrating groundwater age effects on contaminant trends in wells
Variation in the terrestrial isotopic composition and atomic weight of argon
Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape
Hyporheic zone denitrification: controls on effective reaction depth and contribution to whole-stream mass balance
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 movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)
Evaluation of perchlorate sources in the Rialto-Colton and Chino California subbasins using chlorine and oxygen isotope ratio analysis
Educational webtool illustrating groundwater age effects on contaminant trends in wells
Variation in the terrestrial isotopic composition and atomic weight of argon
Soil, plant, and terrain effects on natural perchlorate distribution in a desert landscape
Hyporheic zone denitrification: controls on effective reaction depth and contribution to whole-stream mass balance
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.