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John Karl Böhlke

Improve understanding of physical and biogeochemical processes affecting water quality of groundwater and surface water. Research focus includes multidisciplinary field and laboratory studies to determine factors affecting sources, movement, and fate of nutrients and reactive inorganic contaminants in the hydrologic cycle. Improve the usefulness of stable isotopes and other environmental tracers in hydrology and biogeochemistry by developing new techniques and approaches. Research topics include analytical techniques for stable isotopes in compounds separated from groundwater and surface water, stable isotope forensics, enriched isotope tracer experiments to quantify transport and reaction rates, field and...
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Geochemical data were obtained to investigate the fate and transport of nitrogen in a subterranean estuary near East Falmouth, Massachusetts. The goal of this investigation was to assess nitrogen attenuation in the aquifer under the Eel River Estuary and the adjacent peninsula that was densely populated with residences having septic systems and legacy cesspool inputs of inorganic nitrogen. This estuary is one of many small embayments on Cape Cod where nutrient enrichment can lead to eutrophication and is a major concern for water-quality impairment. Groundwater water-quality data were collected from 3 transects from a total of 27 locations that were sampled between November 2015 and October 2016. Samples were...
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This U.S. Geological Survey (USGS) data release provides a comprehensive dataset of water-quality results, physical-parameter measurements, hydrologic measurements, and site information collected to study the nature and extent of water quality along groundwater flow paths adjacent to glacial-kettle lakes on Cape Cod, Massachusetts. Water-quality samples were collected in 2003, 2005, and 2012 through 2018 in and near seven kettle lakes located on western Cape Cod, with most of the data collected in 2015-2017 from Ashumet Pond, which is located in the towns of Falmouth and Mashpee. Data were also collected at other lakes to compare the lake-specific influences of geochemistry and hydrology on the downgradient groundwater...
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Surface water, pore water, pond bottom sediments, and groundwater were sampled within and downgradient from five groundwater flow-through ponds that ranged from oligotrophic to eutrophic in Cape Cod, Massachusetts during different seasons from 2015 – 2018. The sampled ponds included Ashumet, Santuit, Snake, Shubael, and Longs. Pore water was collected between 15 to 100 cm below the pond bottoms on the upgradient and downgradient sides of the ponds. Groundwater was collected on the downgradient side where the pond water recharges the groundwater resulting in a “pond shadow”. Within the pond shadow, groundwater is under the direct influence of surface water. The pond shadows were sampled vertically and at various...
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This data release contains chemical and isotopic data used in an investigation of nitrate sources and transport in the Upper Illinois River basin. Samples (total = 445) include river water from the Upper Illinois River and its major tributaries plus urban wastewater and agricultural groundwater. Data include concentrations of nitrate, chloride, and sulfate; isotope ratios of N and O in nitrate; and isotope ratios of H and O in water.
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