John Karl Bohlke
Dr. John Karl Bohlke is a Scientist Emeritus with the USGS Water Resources Mission Area and the Reston Stable Isotope Laboratory.
Professional Experience
Hydrologist, National Research Program and Earth System Processes Division, Water Mission Area, US Geological Survey, Reston, Virginia (since 1991)
[Adjunct Assist/Assoc Professor (Geology), University of Maryland (1992-2016)]
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
Minimum energy requirements for desalination of brackish groundwater in the United States with comparison to international datasets
Validation of stable isotope ratio analysis to document the biodegradation and natural attenuation of RDX, ESTCP Project ER-201208
Clarification of the term “normal material” used for standard atomic weights (IUPAC Technical Report)
Preliminary assessment of stable nitrogen and oxygen isotopic composition of USGS51 and USGS52 nitrous oxide reference gases and perspectives on calibration needs
Response of deep groundwater to land use change in desert basins of the Trans-Pecos region, Texas, USA: Effects on infiltration, recharge, and nitrogen fluxes
Tracking the fate of nitrate through pulse-flow wetlands: A mesocosm scale 15N enrichment tracer study
Stable isotope analyses of oxygen (18O:17O:16O) and chlorine (37Cl:35Cl) in perchlorate: reference materials, calibrations, methods, and interferences
Density-driven free-convection model for isotopically fractionated geogenic nitrate in sabkha brine
Stable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data
Brackish groundwater in the United States
Spatial and temporal variation of stream chemistry associated with contrasting geology and land-use patterns in the Chesapeake Bay watershed—Summary of results from Smith Creek, Virginia; Upper Chester River, Maryland; Conewago Creek, Pennsylvania; and Di
Deposition, accumulation, and alteration of Cl−, NO3−, ClO4− and ClO3− salts in a hyper-arid polar environment: Mass balance and isotopic constraints
Science and Products
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Filter Total Items: 195
Minimum energy requirements for desalination of brackish groundwater in the United States with comparison to international datasets
This paper uses chemical and physical data from a large 2017 U.S. Geological Surveygroundwater dataset with wells in the U.S. and three smaller international groundwater datasets with wells primarily in Australia and Spain to carry out a comprehensive investigation of brackish groundwater composition in relation to minimum desalinationenergy costs. First, we compute the site-specific least work reAuthorsYvana D. Ahdab, Gregory P. Thiel, John K. Böhlke, Jennifer S. Stanton, John H. LienhardValidation of stable isotope ratio analysis to document the biodegradation and natural attenuation of RDX, ESTCP Project ER-201208
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a common soil contaminant at current and former military facilities, including many training and testing ranges. Because RDX is readily transported through soils to the subsurface, this nitramine explosive now also impacts groundwater and drinking water at numerous locations across the country. A significant issue with RDX contamination on ranges anAuthorsPaul B. Hatzinger, Mark E. Fuller, Neil C. Sturchio, John K. BöhlkeClarification of the term “normal material” used for standard atomic weights (IUPAC Technical Report)
The standard atomic weights of the elements apply to normal materials. Since 1984, the Commission on Isotopic Abundances and Atomic Weights (Commission) has defined a normal material as:“The material is a reasonably possible source for this element or its compounds in commerce, for industry or science; the material is not itself studied for some extraordinary anomaly and its isotopic composition hAuthorsTyler B. Coplen, Norman E. Holden, Michael E. Wieser, John K. BöhlkePreliminary assessment of stable nitrogen and oxygen isotopic composition of USGS51 and USGS52 nitrous oxide reference gases and perspectives on calibration needs
RationaleDespite a long history and growing interest in isotopic analyses of N2O, there is a lack of isotopically characterized N2O isotopic reference materials (standards) to enable normalization and reporting of isotope‐delta values. Here we report the isotopic characterization of two pure N2O gas reference materials, USGS51 and USGS52, which are now available for laboratory calibration (https:/AuthorsNathaniel E. Ostrom, Hasand Gandhi, Tyler B. Coplen, Sakae Toyoda, John K. Böhlke, Willi A. Brand, Karen L. Casciotti, Jens Dyckmans, Anette Giesemann, Joachim Mohn, Reinhard Well, Longfei Yu, Naohiro YoshidaResponse of deep groundwater to land use change in desert basins of the Trans-Pecos region, Texas, USA: Effects on infiltration, recharge, and nitrogen fluxes
Quantifying the effects of anthropogenic processes on groundwater in arid regions can be complicated by thick unsaturated zones with long transit times. Human activities can alter water and nutrient fluxes, but their impact on groundwater is not always clear. This study of basins in the Trans-Pecos region of Texas links anthropogenic land use and vegetation change with alterations to unsaturated zAuthorsWendy Marie Robertson, John K. Böhlke, John M. SharpTracking the fate of nitrate through pulse-flow wetlands: A mesocosm scale 15N enrichment tracer study
Quantitative information about the fate of applied nitrate (NO3-N) in pulse-flow constructed wetlands is essential for designing wetland treatment systems and assessing their nitrogen removal services for agricultural and stormwater applications. Although many studies have documented NO3-N losses in wetlands, controlled experiments indicating the relative importance of different processes and N siAuthorsTiffany L. Messer, Michael R. Burchell, John K. Böhlke, Craig R. TobiasStable isotope analyses of oxygen (18O:17O:16O) and chlorine (37Cl:35Cl) in perchlorate: reference materials, calibrations, methods, and interferences
RationalePerchlorate (ClO4−) is a common trace constituent of water, soils, and plants; it has both natural and synthetic sources and is subject to biodegradation. The stable isotope ratios of Cl and O provide three independent quantities for ClO4− source attribution and natural attenuation studies: δ37Cl, δ18O, and δ17O (or Δ17O or 17Δ) values. Documented reference materials, calibration schemes,AuthorsJohn K. Böhlke, Stanley J. Mroczkowski, Neil C. Sturchio, Linnea J. Heraty, Kent W. Richman, Donald B. Sullivan, Kris N. Griffith, Baohua Gu, Paul B. HatzingerDensity-driven free-convection model for isotopically fractionated geogenic nitrate in sabkha brine
Subsurface brines with high nitrate (NO3−) concentration are common in desert environments as atmospheric nitrogen is concentrated by the evaporation of precipitation and little nitrogen uptake. However, in addition to having an elevated mean concentration of ∼525 mg/L (as N), NO3− in the coastal sabkhas of Abu Dhabi is enriched in 15N (mean δ15N ∼17‰), which is an enigma. A NO3− solute mass balanAuthorsWarren W. Wood, John K. BöhlkeStable isotopic composition of perchlorate and nitrate accumulated in plants: Hydroponic experiments and field data
Natural perchlorate (ClO4−) in soil and groundwater exhibits a wide range in stable isotopic compositions (δ37Cl, δ18O, and Δ17O), indicating that ClO4− may be formed through more than one pathway and/or undergoes post-depositional isotopic alteration. Plants are known to accumulate ClO4−, but little is known about their ability to alter its isotopic composition. We examined the potential for planAuthorsNubia Luz Estrada, John K. Böhlke, Neil C. Sturchio, Baohua Gu, Greg Harvey, Kent O. Burkey, David A. Grantz, Margaret T. McGrath, Todd A. Anderson, Balaji Rao, Ritesh Sevanthi, Paul B. Hatzinger, W. Andrew JacksonBrackish groundwater in the United States
For some parts of the Nation, large-scale development of groundwater has caused decreases in the amount of groundwater that is present in aquifer storage and that discharges to surface-water bodies. Water supply in some areas, particularly in arid and semiarid regions, is not adequate to meet demand, and severe drought is affecting large parts of the United States. Future water demand is projectedAuthorsJennifer S. Stanton, David W. Anning, Craig J. Brown, Richard B. Moore, Virginia L. McGuire, Sharon L. Qi, Alta C. Harris, Kevin F. Dennehy, Peter B. McMahon, James R. Degnan, John Karl BöhlkeSpatial and temporal variation of stream chemistry associated with contrasting geology and land-use patterns in the Chesapeake Bay watershed—Summary of results from Smith Creek, Virginia; Upper Chester River, Maryland; Conewago Creek, Pennsylvania; and Di
Despite widespread and ongoing implementation of conservation practices throughout the Chesapeake Bay watershed, water quality continues to be degraded by excess sediment and nutrient inputs. While the Chesapeake Bay Program has developed and maintains a large-scale and long-term monitoring network to detect improvements in water quality throughout the watershed, fewer resources have been allocateAuthorsKenneth E. Hyer, Judith M. Denver, Michael J. Langland, James S. Webber, J. K. Böhlke, W. Dean Hively, John W. CluneDeposition, accumulation, and alteration of Cl−, NO3−, ClO4− and ClO3− salts in a hyper-arid polar environment: Mass balance and isotopic constraints
The salt fraction in permafrost soils/sediments of the McMurdo Dry Valleys (MDV) of Antarctica can be used as a proxy for cold desert geochemical processes and paleoclimate reconstruction. Previous analyses of the salt fraction in MDV permafrost soils have largely been conducted in coastal regions where permafrost soils are variably affected by aqueous processes and mixed inputs from marine and stAuthorsAndrew Jackson, Alfonso F. Davila, John Karl Böhlke, Neil C. Sturchio, Ritesh Sevanthi, Nubia Estrada, Maeghan Brundrett, Denis Lacelle, Christopher P. McKay, Armen Poghosyan, Wayne Pollard, Kris Zacny