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
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Assessment of intrinsic bioremediation of jet fuel contamination in a shallow aquifer, Beaufort, South Carolina
Field and laboratory studies show that microorganisms indigenous to the ground-water system underlying Tank Farm C, Marine Corps Air Station Beaufort, S.C., degrade petroleum hydrocarbons under aerobic and anaerobic conditions. Under aerobic conditions, sediments from the shallow aquifer underlying the site mineralized radiolabeled (14C) toluene to 14CO2 with first-order rate constants of about -
Comparison of Eh and H2 measurements for delineating redox processes in a contaminated aquifer
Measurements of oxidation-reduction potential (Eh) and concentrations of dissolved hydrogen (H2) were made in a shallow groundwater system contaminated with solvents and jet fuel to delineate the zonation of redox processes. Eh measurements ranged from +69 to -158 mV in a cross section of the contaminated plume and accurately delineated oxic from anoxic groundwater. Plotting measured Eh and pH val
Influence of electron donor on the minimum sulfate concentration required for sulfate reduction in a petroleum hydrocarbon-contaminated aquifer
Fluctuations in the availability of electron donor (petroleum hydrocarbons) affected the competition between sulfate-reducing bacteria (SRB) and methanogenic bacteria (MB) for control of electron flow in a petroleum hydrocarbon-contaminated aquifer. The data suggest that abundant electron donor availability allowed MB to sequester a portion of the electron flow even when sulfate was present in suf
Measuring rates of biodegradation in a contaminated aquifer using field and laboratory methods
Rates of biodegradation were measured in a petroleum hydrocarbon-contaminated aquifer using a combination of field and laboratory methods. These methods are based on tracking concentration changes of substrates (both electron donors and acceptors) or final products of microbial metabolism over time. Ground water at the study site (Hanahan, South Carolina) is anoxic, and sulfate reduction it the pr
Microbial acetogenesis as a source of organic acids in ancient Atlantic Coastal Plain sediments
Field and laboratory evidence shows that deeply buried (90-888 m) fine-grained sediments of the Atlantic Coastal Plain contain viable acetogenic microorganisms, and that these microorganisms actively produce organic acids. Concentrations of formate, acetate, and propionate in pore waters extracted from fine-grained sediments ranged from 50 ??M to 5 mM and were much higher than in adjacent pore wat
Anaerobic mineralization of vinyl chloride in Fe(III)-reducing, aquifer sediments
Within anaerobic aquifer systems, reductive dehalogenation of polychlorinated ethenes commonly results in the accumulation of vinyl chloride, which is highly toxic and carcinogenic to humans. Anaerobic reduction of vinyl chloride is considered to be slow and incomplete. Here, we provide the first evidence for anaerobic oxidation of vinyl chloride under Fe(III)reducing conditions. Addition of chela
Factors affecting microbial 2,4,6-trinitrotoluene mineralization in contaminated soil
The influence of selected environmental factors on microbial TNT mineralization in soils collected from a TNT-contaminated site at Weldon Spring, MO, was examined using uniformly ring-labeled [14C]TNT. Microbial TNT mineralization was significantly inhibited by the addition of cellobiose and syringate. This response suggests that the indigenous microorganisms are capable of metabolizing TNT but pr
Microbial transformation of nitroaromatics in surface soils and aquifer materials
Microorganisms indigenous to surface soils and aquifer materials collected at a munitions-contaminated site transformed 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) to amino-nitro intermediates within 20 to 70 days. Carbon mineralization studies with both unlabeled (TNT, 2,4-DNT, and 2,6-DNT) and radiolabeled ([14C]TNT) substrates indicated that a sig
Effect of atrazine on potential denitrification in aquifer sediments
Agriculturaf use of fertilizers and herbicides has often resulted in nitrate and atrazine contamination of the shallow aquifers that underlay cultivated fields. In several cases, the concentrations of atrazine and nitrate dissolved in ground water are positively correlated (Spalding ef al., 1979; Chen and Druliner, 1987; Spalding et al., 1989). Because simultaneous application of nitrate fertilize
Biodegradation potential of chlorinated solvents in ground water at the Naval Surface Warfare Center, Louisville, Kentucky, July 1999 to February 2000
The U.S. Geological Survey, in cooperation
with the U.S. Department of the Navy, Southern
Division Naval Facilities Engineering Command,
investigated the potential for biodegradation of
chlorinated solvents in ground water at the Naval
Surface Warfare Center (also known as the Naval
Ordnance Station, or the station), Louisville,
Kentucky. The subsurface down to at least 100 feet
at the sta
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Assessment of intrinsic bioremediation of jet fuel contamination in a shallow aquifer, Beaufort, South Carolina
Field and laboratory studies show that microorganisms indigenous to the ground-water system underlying Tank Farm C, Marine Corps Air Station Beaufort, S.C., degrade petroleum hydrocarbons under aerobic and anaerobic conditions. Under aerobic conditions, sediments from the shallow aquifer underlying the site mineralized radiolabeled (14C) toluene to 14CO2 with first-order rate constants of about -Comparison of Eh and H2 measurements for delineating redox processes in a contaminated aquifer
Measurements of oxidation-reduction potential (Eh) and concentrations of dissolved hydrogen (H2) were made in a shallow groundwater system contaminated with solvents and jet fuel to delineate the zonation of redox processes. Eh measurements ranged from +69 to -158 mV in a cross section of the contaminated plume and accurately delineated oxic from anoxic groundwater. Plotting measured Eh and pH valInfluence of electron donor on the minimum sulfate concentration required for sulfate reduction in a petroleum hydrocarbon-contaminated aquifer
Fluctuations in the availability of electron donor (petroleum hydrocarbons) affected the competition between sulfate-reducing bacteria (SRB) and methanogenic bacteria (MB) for control of electron flow in a petroleum hydrocarbon-contaminated aquifer. The data suggest that abundant electron donor availability allowed MB to sequester a portion of the electron flow even when sulfate was present in sufMeasuring rates of biodegradation in a contaminated aquifer using field and laboratory methods
Rates of biodegradation were measured in a petroleum hydrocarbon-contaminated aquifer using a combination of field and laboratory methods. These methods are based on tracking concentration changes of substrates (both electron donors and acceptors) or final products of microbial metabolism over time. Ground water at the study site (Hanahan, South Carolina) is anoxic, and sulfate reduction it the prMicrobial acetogenesis as a source of organic acids in ancient Atlantic Coastal Plain sediments
Field and laboratory evidence shows that deeply buried (90-888 m) fine-grained sediments of the Atlantic Coastal Plain contain viable acetogenic microorganisms, and that these microorganisms actively produce organic acids. Concentrations of formate, acetate, and propionate in pore waters extracted from fine-grained sediments ranged from 50 ??M to 5 mM and were much higher than in adjacent pore watAnaerobic mineralization of vinyl chloride in Fe(III)-reducing, aquifer sediments
Within anaerobic aquifer systems, reductive dehalogenation of polychlorinated ethenes commonly results in the accumulation of vinyl chloride, which is highly toxic and carcinogenic to humans. Anaerobic reduction of vinyl chloride is considered to be slow and incomplete. Here, we provide the first evidence for anaerobic oxidation of vinyl chloride under Fe(III)reducing conditions. Addition of chelaFactors affecting microbial 2,4,6-trinitrotoluene mineralization in contaminated soil
The influence of selected environmental factors on microbial TNT mineralization in soils collected from a TNT-contaminated site at Weldon Spring, MO, was examined using uniformly ring-labeled [14C]TNT. Microbial TNT mineralization was significantly inhibited by the addition of cellobiose and syringate. This response suggests that the indigenous microorganisms are capable of metabolizing TNT but prMicrobial transformation of nitroaromatics in surface soils and aquifer materials
Microorganisms indigenous to surface soils and aquifer materials collected at a munitions-contaminated site transformed 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), and 2,6-dinitrotoluene (2,6-DNT) to amino-nitro intermediates within 20 to 70 days. Carbon mineralization studies with both unlabeled (TNT, 2,4-DNT, and 2,6-DNT) and radiolabeled ([14C]TNT) substrates indicated that a sigEffect of atrazine on potential denitrification in aquifer sediments
Agriculturaf use of fertilizers and herbicides has often resulted in nitrate and atrazine contamination of the shallow aquifers that underlay cultivated fields. In several cases, the concentrations of atrazine and nitrate dissolved in ground water are positively correlated (Spalding ef al., 1979; Chen and Druliner, 1987; Spalding et al., 1989). Because simultaneous application of nitrate fertilizeBiodegradation potential of chlorinated solvents in ground water at the Naval Surface Warfare Center, Louisville, Kentucky, July 1999 to February 2000
The U.S. Geological Survey, in cooperation with the U.S. Department of the Navy, Southern Division Naval Facilities Engineering Command, investigated the potential for biodegradation of chlorinated solvents in ground water at the Naval Surface Warfare Center (also known as the Naval Ordnance Station, or the station), Louisville, Kentucky. The subsurface down to at least 100 feet at the sta - News