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
Degradation of RDX (Hexahydro-1,3,5-trinitro-1,3,5-triazine) in contrasting coastal marine habitats: Subtidal non-vegetated (sand), subtidal vegetated (silt/eel grass), and intertidal marsh
DGMETA (version 1)—Dissolved gas modeling and environmental tracer analysis computer program
Reactive transport modeling to understand attenuation of arsenic concentrations in anoxic groundwater during Fe(II) oxidation by nitrate
The influence of sample matrix on the accuracy of nitrite N and O isotope ratio analyses with the azide method
Assessing the seasonal dynamics of nitrate and sulfate aerosols at the South Pole utilizing stable isotopes
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
Methane and nitrous oxide temporal and spatial variability in two midwestern USA streams containing high nitrate concentrations
Constraining the oxygen isotopic composition of nitrate produced by nitrification
IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the education community (IUPAC Technical Report)
Seasonality of nitrate sources and isotopic composition in the Upper Illinois River
Four-dimensional isotopic approach to identify perchlorate sources in groundwater: Application to the Rialto-Colton and Chino subbasins, southern California (USA)
Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14
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
Degradation of RDX (Hexahydro-1,3,5-trinitro-1,3,5-triazine) in contrasting coastal marine habitats: Subtidal non-vegetated (sand), subtidal vegetated (silt/eel grass), and intertidal marsh
DGMETA (version 1)—Dissolved gas modeling and environmental tracer analysis computer program
Reactive transport modeling to understand attenuation of arsenic concentrations in anoxic groundwater during Fe(II) oxidation by nitrate
The influence of sample matrix on the accuracy of nitrite N and O isotope ratio analyses with the azide method
Assessing the seasonal dynamics of nitrate and sulfate aerosols at the South Pole utilizing stable isotopes
Seasonal and spatial variation in the location and reactivity of a nitrate-contaminated groundwater discharge zone in a lakebed
Methane and nitrous oxide temporal and spatial variability in two midwestern USA streams containing high nitrate concentrations
Constraining the oxygen isotopic composition of nitrate produced by nitrification
IUPAC Periodic Table of the Elements and Isotopes (IPTEI) for the education community (IUPAC Technical Report)
Seasonality of nitrate sources and isotopic composition in the Upper Illinois River
Four-dimensional isotopic approach to identify perchlorate sources in groundwater: Application to the Rialto-Colton and Chino subbasins, southern California (USA)
Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14
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.