Paul M Bradley
Introduction: Research Hydrologist/Ecologist with the South Atlantic Water Science Center focused on understanding environmental contaminant mixture exposures and real versus perceived effects to human and environmental health.
Paul is project lead, along with Kelly Smalling, of the Drinking-Water and Wastewater Infrastructure Integrated Science Team of the Ecosystems Mission, Environmental Health Program. His research focuses on human exposures to and potential effects of inorganic, organic, and microbial contaminant mixtures in drinking water at the point of use and on anthropogenic contaminant mixtures as ecosystem stressors.
Professional Experience
1988–present: Research Ecologist/Hydrologist, U.S. Geological Survey
Expertise:
• Contaminant mixtures
• Drinking water
• Water quality
• Environmental health
Education and Certifications
B.S., Applied Biology, Georgia Institute of Technology, Atlanta, Georgia
M.S., Applied Biology, Georgia Institute of Technology, Atlanta, Georgia
Ph.D., Physiological Ecology, University of South Carolina, Columbia, South Carolina
Science and Products
Fluvial transport of mercury, organic carbon, suspended sediment, and selected major ions in contrasting stream basins in South Carolina and New York, October 2004 to September 2009
Intra- and inter-basin mercury comparisons: Importance of basin scale and time-weighted methylmercury estimates
Comparison of TOPMODEL streamflow simulations using NEXRAD-based and measured rainfall data, McTier Creek watershed, South Carolina
Mercury bioaccumulation studies in the National Water-Quality Assessment Program--biological data from New York and South Carolina, 2005-2009
Shallow groundwater mercury supply in a coastal plain stream
Threshold amounts of organic carbon needed to initiate reductive dechlorination in groundwater systems
Perils of categorical thinking: "Oxic/anoxic" conceptual model in environmental remediation
Landscape controls on total and methyl Hg in the Upper Hudson River basin, New York, USA
Microbial mineralization of cis-dichloroethene and vinyl chloride as a component of natural attenuation of chloroethene contaminants under conditions identified in the field as anoxic
Estimated trichloroethene transformation rates due to naturally occurring biodegradation in a fractured-rock aquifer
Characterizing mercury concentrations and fluxes in a Coastal Plain watershed: Insights from dynamic modeling and data
Dissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater
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Fluvial transport of mercury, organic carbon, suspended sediment, and selected major ions in contrasting stream basins in South Carolina and New York, October 2004 to September 2009
A spatially extensive assessment of the environmental controls on mercury transport and bioaccumulation in stream ecosystems in New York and South Carolina was conducted as part of the U.S. Geological Survey National Water-Quality Assessment Program and included the determination of fluvial transport of mercury and associated constituents during water years 2005–2009. (A water year extends from OcAuthorsCeleste A. Journey, Douglas A. Burns, Karen Riva-Murray, Mark E. Brigham, Daniel T. Button, Toby D. Feaster, Matthew D. Petkewich, Paul M. BradleyIntra- and inter-basin mercury comparisons: Importance of basin scale and time-weighted methylmercury estimates
To assess inter-comparability of fluvial mercury (Hg) observations at substantially different scales, Hg concentrations, yields, and bivariate-relations were evaluated at nested-basin locations in the Edisto River, South Carolina and Hudson River, New York. Differences between scales were observed for filtered methylmercury (FMeHg) in the Edisto (attributed to wetland coverage differences) but notAuthorsPaul M. Bradley, Celeste A. Journey, Mark E. Bringham, Douglas A. Burns, Daniel T. Button, Karen Riva-MurrayComparison of TOPMODEL streamflow simulations using NEXRAD-based and measured rainfall data, McTier Creek watershed, South Carolina
Rainfall is an important forcing function in most watershed models. As part of a previous investigation to assess interactions among hydrologic, geochemical, and ecological processes that affect fish-tissue mercury concentrations in the Edisto River Basin, the topography-based hydrological model (TOPMODEL) was applied in the McTier Creek watershed in Aiken County, South Carolina. Measured rainfallAuthorsToby D. Feaster, Nancy E. Westcott, Robert J.M. Hudson, Paul Conrads, Paul M. BradleyMercury bioaccumulation studies in the National Water-Quality Assessment Program--biological data from New York and South Carolina, 2005-2009
The U.S. Geological Survey National Water-Quality Assessment Program conducted a multidisciplinary study from 2005–09 to investigate the bioaccumulation of mercury in streams from two contrasting environmental settings. Study areas were located in the central Adirondack Mountains region of New York and the Inner Coastal Plain of South Carolina. Fish, macroinvertebrates, periphyton (attached algaeAuthorsKaren M. Beaulieu, Daniel T. Button, Barbara C. Scudder Eikenberry, Karen Riva-Murray, Lia C. Chasar, Paul M. Bradley, Douglas A. BurnsShallow groundwater mercury supply in a coastal plain stream
Fluvial methylmercury (MeHg) is attributed to methylation in up-gradient wetland areas. This hypothesis depends on efficient wetland-to-stream hydraulic transport under nonflood and flood conditions. Fluxes of water and dissolved (filtered) mercury (Hg) species (FMeHg and total Hg (FTHg)) were quantified in April and July of 2009 in a reach at McTier Creek, South Carolina to determine the relativeAuthorsPaul M. Bradley, Celeste A. Journey, Mark A. Lowery, Mark E. Brigham, Douglas A. Burns, Daniel T. Button, Francis H. Chapelle, Michelle A. Lutz, Mark C. Marvin-DiPasquale, Karen Riva-MurrayThreshold amounts of organic carbon needed to initiate reductive dechlorination in groundwater systems
Aquifer sediment and groundwater chemistry data from 15 Department of Defense facilities located throughout the United States were collected and analyzed with the goal of estimating the amount of natural organic carbon needed to initiate reductive dechlorination in groundwater systems. Aquifer sediments were analyzed for hydroxylamine and NaOH-extractable organic carbon, yielding a probable undereAuthorsFrancis H. Chapelle, Lashun K. Thomas, Paul M. Bradley, Heather V. Rectanus, Mark A. WiddowsonPerils of categorical thinking: "Oxic/anoxic" conceptual model in environmental remediation
Given ambient atmospheric oxygen concentrations of about 21 percent (by volume), the lower limit for reliable quantitation of dissolved oxygen concentrations in groundwater samples is in the range of 0.1–0.5 mg/L. Frameworks for assessing in situ redox condition are often applied using a simple two-category (oxic/anoxic) model of oxygen condition. The "oxic" category defines the environmental rangAuthorsPaul M. BradleyLandscape controls on total and methyl Hg in the Upper Hudson River basin, New York, USA
Approaches are needed to better predict spatial variation in riverine Hg concentrations across heterogeneous landscapes that include mountains, wetlands, and open waters. We applied multivariate linear regression to determine the landscape factors and chemical variables that best account for the spatial variation of total Hg (THg) and methyl Hg (MeHg) concentrations in 27 sub-basins across the 493AuthorsDouglas A. Burns, K. Riva-Murray, P. M. Bradley, G. R. Aiken, M. E. BrighamMicrobial mineralization of cis-dichloroethene and vinyl chloride as a component of natural attenuation of chloroethene contaminants under conditions identified in the field as anoxic
Chlororespiration is a key component of remediation at many chloroethene-contaminated sites. In some instances, limited accumulation of reductive dechlorination daughter products may suggest that natural attenuation is not adequate for site remediation. This conclusion is justified when evidence for parent compound (tetrachloroethene, PCE, or trichloroethene, TCE) degradation is lacking. For manyAuthorsPaul M. BradleyEstimated trichloroethene transformation rates due to naturally occurring biodegradation in a fractured-rock aquifer
Rates of trichloroethene (TCE) mass transformed by naturally occurring biodegradation processes in a fractured rock aquifer underlying a former Naval Air Warfare Center (NAWC) site in West Trenton, New Jersey, were estimated. The methodology included (1) dividing the site into eight elements of equal size and vertically integrating observed concentrations of two daughter products of TCE biodegradaAuthorsFrancis H. Chapelle, Pierre J. Lacombe, Paul M. BradleyCharacterizing mercury concentrations and fluxes in a Coastal Plain watershed: Insights from dynamic modeling and data
Mercury (Hg) is one of the leading water quality concerns in surface waters of the United States. Although watershed-scale Hg cycling research has increased in the past two decades, advances in modeling watershed Hg processes in diverse physiographic regions, spatial scales, and land cover types are needed. The goal of this study was to assess Hg cycling in a Coastal Plain system using concentratiAuthorsH.E. Golden, C.D. Knightes, P.A. Conrads, G. M. Davis, T.D. Feaster, C.A. Journey, S.T. Benedict, M. E. Brigham, P. M. BradleyDissolved oxygen as an indicator of bioavailable dissolved organic carbon in groundwater
Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in tAuthorsFrancis H. Chapelle, Paul M. Bradley, Peter B. McMahon, Karl Kaiser, Ron Benner - Web Tools
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