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Douglas Kent

Hydrologist

Contact Info


Short Biography

Doug Kent received a BA in chemistry from the University of California, San Diego and a PhD from Scripps Institution of Oceanography.  He has conducted hydrologic research at the USGS since 1985.



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Publications

Savoie, Jennifer G.; Smith, Richard L.; Kent, Douglas B.; Hess, Kathryn M.; LeBlanc, Denis R.; Barber, Larry B., 2006. Ground-Water-Quality Data for a Treated-Wastewater Plume Undergoing Natural Restoration, Ashumet Valley, Cape Cod, Massachusetts, 1994-2004. Data Series 198, CD-ROM [Link]

Savoie, Jennifer G.; Kent, Douglas B.;S mith, Richard L.; LeBlanc, Denis R.; Hubble, David W., 2004. Changes in Ground-Water Quality near Two Granular-Iron Permeable Reactive Barriers in a Sand and Gravel Aquifer, Cape Cod, Massachusetts, 1997-2000. Water-Resources Investigations Report 2003-4309, 84 p. [Link]

McCobb, Timothy D.; LeBlanc, Denis R.; Walter, Donald A.; Hess, Kathryn M.; Kent, Douglas B.; Smith, Richard L., 2003. Phosphorus in a ground-water contaminant plume discharging to Ashumet Pond, Cape Cod, Massachusetts, 1999. Water-Resources Investigations Report 2002-4306, 77 p. [Link]

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My Science Topics


Science Topic
Subtopic
Environmental Issuesground-water quality
Environmental Issueshuman impacts
Environmental Issuestoxic radionuclides
Environmental Issuestoxic trace elements
Environmental Issueswaste treatment and disposal
Environmental Issueswater quality


Understanding the impact of mineral-water interface reactions on contaminant mobility

The objectives of my research are to develop a fundamental understanding of chemical reactions at mineral-water interfaces, to understand the coupling between these reactions and physical and biological processes, and to develop conceptual and quantitative models that are broadly applicable to understanding and predicting metal and metalloid transport, mobilization, and sequestration in groundwater across the range of spatial and temporal scales required in field applications.  Critical elements include understanding properties of natural materials that control chemical reactivity, developing conceptual and quantitative models that describe mineral-water interface reactions, and applying these models in reactive transport simulations at the field-scale.  We have applied these approaches to improve understanding of the mobility of many groundwater contaminants, including arsenic, cesium, chromium, copper, iodine, lead, nickel, uranium, and zinc.

Chemical reactivity of natural sediments is often controlled by constituents of sediment-grain coatings, which can consist of nanometer-scale materials with variable composition and degree of crystallinity.  Advanced molecular and microscopic methods are used to characterize sorbent phases and sorbed metal speciation.  These methods are applied in conjunction with more broadly accessible macroscopic methods to advance understanding of chemical properties of natural materials.  Laboratory experimental studies of solute uptake and release are conducted with both natural materials and synthetic analogues.  Models that can account for the impact of variable chemistry on solute uptake and release are developed.

Conceptual and, where possible, quantitative models of contaminant metal-ion release, transport, and uptake are tested using field studies.  Field studies include characterization studies and field manipulation experiments.  Field characterization studies involve determining the spatial and temporal distributions of fluid- and solid-phase contaminant concentrations and, where possible, chemical speciation of sorbed contaminants.  In addition we need to understand the spatial and temporal distributions of solutes that influence chemical speciation of contaminants, such as pH and the concentrations of redox-reactive species.  Some field manipulation studies involve injecting reactive solutes under well-understood biogeochemical conditions and observing solute concentrations and speciation over time and space.  Other field manipulation studies involve perturbing local biogeochemical conditions and determining the impact on contaminant concentrations, speciation, and mobility.


Contact Information

Douglas Kent
Bldg 15, McKelvey Building, 345 Middlefield Road
Menlo Park, CA 94025-3561
dbkent@usgs.gov
650-329-4461
650-329-4463 - Fax
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