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
Determination of δ18O and δ15N in Nitrate
Hydrogeologic and water-quality data used to evaluate the effects of focused recharge on ground-water quality near Princeton, Minnesota, 1991-95
Water quality at production wells near artificial-recharge basins in Montebello Forebay, Los Angeles County
Tritium/3He dating of river infiltration: An example from the Danube in the Szigetköz area, Hungary
Stable isotope evidence for an atmospheric origin of desert nitrate deposits in northern Chile and southern California, U.S.A.
Groundwater record of halocarbon transport by the Danube River
Tritium/3He dating of river infiltration: an example from the Danube in the Szigetkoz Area, Hungary
Chemical and stable-isotope data from an experiment to examine temporal variability in water samples from screened wells on Cape Cod, Massachusetts, 1994
Isotope hydrology studies in the Szigetköz region, northwest Hungary
Groundwater origin and dating studies in Szigetkoz
Denitrification and mixing in a stream-aquifer system: Effects on nitrate loading to surface water
Combined use of groundwater dating, chemical, and isotopic analyses to resolve the history and fate of nitrate contamination in two agricultural watersheds, Atlantic coastal plain, Maryland
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
Determination of δ18O and δ15N in Nitrate
Hydrogeologic and water-quality data used to evaluate the effects of focused recharge on ground-water quality near Princeton, Minnesota, 1991-95
Water quality at production wells near artificial-recharge basins in Montebello Forebay, Los Angeles County
Tritium/3He dating of river infiltration: An example from the Danube in the Szigetköz area, Hungary
Stable isotope evidence for an atmospheric origin of desert nitrate deposits in northern Chile and southern California, U.S.A.
Groundwater record of halocarbon transport by the Danube River
Tritium/3He dating of river infiltration: an example from the Danube in the Szigetkoz Area, Hungary
Chemical and stable-isotope data from an experiment to examine temporal variability in water samples from screened wells on Cape Cod, Massachusetts, 1994
Isotope hydrology studies in the Szigetköz region, northwest Hungary
Groundwater origin and dating studies in Szigetkoz
Denitrification and mixing in a stream-aquifer system: Effects on nitrate loading to surface water
Combined use of groundwater dating, chemical, and isotopic analyses to resolve the history and fate of nitrate contamination in two agricultural watersheds, Atlantic coastal plain, Maryland
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.