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
Chlorine-36 as a tracer of perchlorate origin
Biogeochemistry at a wetland sediment-alluvial aquifer interface in a landfill leachate plume
Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA
Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes
Determination of the delta(15N/14N)of Ammonium (NH4+) in Water: RSIL Lab Code 2898
Ecohydrological factors affecting nitrate concentrations in a phreatic desert aquifer in northwestern China
Limited occurrence of denitrification in four shallow aquifers in agricultural areas of the United States
Source and transport controls on the movement of nitrate to public supply wells in selected principal aquifers of the United States
Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters
Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from water samples
Simulated response of water quality in public supply wells to land use change
Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003
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
Chlorine-36 as a tracer of perchlorate origin
Biogeochemistry at a wetland sediment-alluvial aquifer interface in a landfill leachate plume
Flow and geochemistry of groundwater beneath a back-barrier lagoon: The subterranean estuary at Chincoteague Bay, Maryland, USA
Dynamic modeling of nitrogen losses in river networks unravels the coupled effects of hydrological and biogeochemical processes
Determination of the delta(15N/14N)of Ammonium (NH4+) in Water: RSIL Lab Code 2898
Ecohydrological factors affecting nitrate concentrations in a phreatic desert aquifer in northwestern China
Limited occurrence of denitrification in four shallow aquifers in agricultural areas of the United States
Source and transport controls on the movement of nitrate to public supply wells in selected principal aquifers of the United States
Mass balance and isotope effects during nitrogen transport through septic tank systems with packed-bed (sand) filters
Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from water samples
Simulated response of water quality in public supply wells to land use change
Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003
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.