Peter B McMahon
Peter is a Research Hydrologist with the USGS Colorado Water Science Center in Lakewood, CO.
Pete McMahon’s current research interests include understanding the effects of hydrocarbon production activities on groundwater quality and identifying natural and human processes that create regional- and national-scale patterns in the chemistry of groundwater. He uses geochemical, isotope, noble-gas, and groundwater-age tracers to understand the origin and fate of chemicals of concern in groundwater.
Education and Certifications
Ph.D., 1990, Geology, University of South Carolina at Columbia
M.A., 1984, Geology, University of Texas at Austin
B.S., 1981, Geology, University of Missouri at Columbia
Science and Products
Filter Total Items: 14
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Use of geochemical, isotopic, and age tracer data to develop models of groundwater flow for the purpose of water management, northern High Plains aquifer, USA
A prolonged drought in the High Plains of Nebraska prompted the use of groundwater for cooling at the largest coal-fired power plant in the State. Prior to the drought, groundwater was used primarily for irrigation and the power plant relied exclusively on surface water stored in a nearby reservoir for cooling. Seepage from the reservoir system during the past ∼75 a has resulted in the buildup of
Authors
Peter B. McMahon, C. P. Carney, E. P. Poeter, Steven M. Peterson
Redox Conditions in Selected Principal Aquifers of the United States
Reduction/oxidation (redox) processes affect the quality of groundwater in all aquifer systems. Redox processes can alternately mobilize or immobilize potentially toxic metals associated with naturally occurring aquifer materials, contribute to the degradation or preservation of anthropogenic contami-nants, and generate undesirable byproducts, such as dissolved manganese (Mn2+), ferrous iron (Fe2+
Authors
P. B. McMahon, T.K. Cowdery, F. H. Chapelle, B.C. Jurgens
Water Quality in the High Plains Aquifer, Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming, 1999-2004
This report contains the major findings of a 1999-2004 assessment of water quality in the High Plains aquifer. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings for principal and other aquifers and major river basins across the Nation. In these reports, water quality is discussed in terms of local, regional, State, and national is
Authors
Jason J. Gurdak, Peter B. McMahon, Kevin Dennehy, Sharon L. Qi
An Excel Workbook for Identifying Redox Processes in Ground Water
The reduction/oxidation (redox) condition of ground water affects the concentration, transport, and fate of many anthropogenic and natural contaminants. The redox state of a ground-water sample is defined by the dominant type of reduction/oxidation reaction, or redox process, occurring in the sample, as inferred from water-quality data. However, because of the difficulty in defining and applying a
Authors
Bryant C. Jurgens, Peter B. McMahon, Francis H. Chapelle, Sandra M. Eberts
What does "water quality" mean?
No abstract available.
Authors
Francis H. Chapelle, Paul M. Bradley, Peter B. McMahon, Bruce Lindsey
Biodegradation of 17β-estradiol, estrone, and testosterone in stream sediments
The release of endocrine-disrupting chemicals (EDCs) in wastewater treatment plant (WWTP) effluent poses a significant threat to the ecology of surface water receptors, due to impacts on the hormonal control, sexual development, reproductive success and community structure of the indigenous aquatic organisms and associated wildlife. Among the EDCs commonly observed in WWTP effluent, the natural [e
Authors
P. M. Bradley, F. H. Chapelle, L. B. Barber, P. B. McMahon, J.L. Gray, D.W. Kolpin
Distinguishing iron-reducing from sulfate-reducing conditions
Ground water systems dominated by iron‐ or sulfate‐reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe2+) and sulfide (sum of H2S, HS−, and S= species and denoted here as “H2S”). This approach is based on the observation that concentrations of Fe2+ and H2S in ground water systems tend to be inversely related according to a hyperbolic function. That is, when F
Authors
F. H. Chapelle, P. M. Bradley, M.A. Thomas, P. B. McMahon
Biodegradation of 17β-estradiol, estrone and testosterone in stream sediments
Biodegradation of 17β-estradiol (E2), estrone (E1), and testosterone (T) was investigated in three wastewater treatment plant (WWTP) affected streams in the United States. Relative differences in the mineralization of [4-14C] substrates were assessed in oxic microcosms containing saturated sediment or water-only from locations upstream and downstream of the WWTP outfall in each system. Upstream se
Authors
Paul M. Bradley, Larry B. Barber, Francis H. Chapelle, James L. Gray, Dana W. Kolpin, Peter B. McMahon
Hydrogeology, Chemical Characteristics, and Transport Processes in the Zone of Contribution of a Public-Supply Well in York, Nebraska
In 2001, the U.S. Geological Survey, as part of the National Water Quality Assessment (NAWQA) Program, initiated a topical study of Transport of Anthropogenic and Natural Contaminants (TANC) to PSW (public-supply wells). Local-scale and regional-scale TANC study areas were delineated within selected NAWQA study units for intensive study of processes effecting transport of contaminants to PSWs. Thi
Authors
Matthew K. Landon, Brian R. Clark, Peter B. McMahon, Virginia L. McGuire, Michael J. Turco
Simulated response of water quality in public supply wells to land use change
Understanding how changes in land use affect water quality of public supply wells (PSW) is important because of the strong influence of land use on water quality, the rapid pace at which changes in land use are occurring in some parts of the world, and the large contribution of groundwater to the global water supply. In this study, groundwater flow models incorporating particle tracking and reacti
Authors
P. B. McMahon, K.R. Burow, L. J. Kauffman, S. M. Eberts, J.K. Böhlke, J.J. Gurdak
Source and transport controls on the movement of nitrate to public supply wells in selected principal aquifers of the United States
In 2003–2005, systematic studies in four contrasting hydrogeologic settings were undertaken to improve understanding of source and transport controls on nitrate movement to public supply wells (PSW) in principal aquifers of the United States. Chemical, isotopic, and age tracer data show that agricultural fertilizers and urban septic leachate were the primary sources of large nitrate concentrations
Authors
P. B. McMahon, J.K. Böhlke, L. J. Kauffman, K.L. Kipp, M.K. Landon, C. A. Crandall, K.R. Burow, C. J. Brown
Potential for 4-n-nonylphenol biodegradation in stream sediments
The potential for in situ biodegradation of 4-nonylphenol (4-NP) was investigated in three hydrologically distinct streams impacted by wastewater treatment plants (WWTPs) in the United States. Microcosms were prepared with sediments from each site and amended with [U-ring-14C]4-n-nonylphenol (4-n-NP) as a model test substrate. Microcosms prepared with sediment collected upstream of the WWTP outfal
Authors
P. M. Bradley, L. B. Barber, D.W. Kolpin, P. B. McMahon, F. H. Chapelle
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Use of geochemical, isotopic, and age tracer data to develop models of groundwater flow for the purpose of water management, northern High Plains aquifer, USA
A prolonged drought in the High Plains of Nebraska prompted the use of groundwater for cooling at the largest coal-fired power plant in the State. Prior to the drought, groundwater was used primarily for irrigation and the power plant relied exclusively on surface water stored in a nearby reservoir for cooling. Seepage from the reservoir system during the past ∼75 a has resulted in the buildup ofAuthorsPeter B. McMahon, C. P. Carney, E. P. Poeter, Steven M. PetersonRedox Conditions in Selected Principal Aquifers of the United States
Reduction/oxidation (redox) processes affect the quality of groundwater in all aquifer systems. Redox processes can alternately mobilize or immobilize potentially toxic metals associated with naturally occurring aquifer materials, contribute to the degradation or preservation of anthropogenic contami-nants, and generate undesirable byproducts, such as dissolved manganese (Mn2+), ferrous iron (Fe2+AuthorsP. B. McMahon, T.K. Cowdery, F. H. Chapelle, B.C. JurgensWater Quality in the High Plains Aquifer, Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming, 1999-2004
This report contains the major findings of a 1999-2004 assessment of water quality in the High Plains aquifer. It is one of a series of reports by the National Water-Quality Assessment (NAWQA) Program that present major findings for principal and other aquifers and major river basins across the Nation. In these reports, water quality is discussed in terms of local, regional, State, and national isAuthorsJason J. Gurdak, Peter B. McMahon, Kevin Dennehy, Sharon L. QiAn Excel Workbook for Identifying Redox Processes in Ground Water
The reduction/oxidation (redox) condition of ground water affects the concentration, transport, and fate of many anthropogenic and natural contaminants. The redox state of a ground-water sample is defined by the dominant type of reduction/oxidation reaction, or redox process, occurring in the sample, as inferred from water-quality data. However, because of the difficulty in defining and applying aAuthorsBryant C. Jurgens, Peter B. McMahon, Francis H. Chapelle, Sandra M. EbertsWhat does "water quality" mean?
No abstract available.AuthorsFrancis H. Chapelle, Paul M. Bradley, Peter B. McMahon, Bruce LindseyBiodegradation of 17β-estradiol, estrone, and testosterone in stream sediments
The release of endocrine-disrupting chemicals (EDCs) in wastewater treatment plant (WWTP) effluent poses a significant threat to the ecology of surface water receptors, due to impacts on the hormonal control, sexual development, reproductive success and community structure of the indigenous aquatic organisms and associated wildlife. Among the EDCs commonly observed in WWTP effluent, the natural [eAuthorsP. M. Bradley, F. H. Chapelle, L. B. Barber, P. B. McMahon, J.L. Gray, D.W. KolpinDistinguishing iron-reducing from sulfate-reducing conditions
Ground water systems dominated by iron‐ or sulfate‐reducing conditions may be distinguished by observing concentrations of dissolved iron (Fe2+) and sulfide (sum of H2S, HS−, and S= species and denoted here as “H2S”). This approach is based on the observation that concentrations of Fe2+ and H2S in ground water systems tend to be inversely related according to a hyperbolic function. That is, when FAuthorsF. H. Chapelle, P. M. Bradley, M.A. Thomas, P. B. McMahonBiodegradation of 17β-estradiol, estrone and testosterone in stream sediments
Biodegradation of 17β-estradiol (E2), estrone (E1), and testosterone (T) was investigated in three wastewater treatment plant (WWTP) affected streams in the United States. Relative differences in the mineralization of [4-14C] substrates were assessed in oxic microcosms containing saturated sediment or water-only from locations upstream and downstream of the WWTP outfall in each system. Upstream seAuthorsPaul M. Bradley, Larry B. Barber, Francis H. Chapelle, James L. Gray, Dana W. Kolpin, Peter B. McMahonHydrogeology, Chemical Characteristics, and Transport Processes in the Zone of Contribution of a Public-Supply Well in York, Nebraska
In 2001, the U.S. Geological Survey, as part of the National Water Quality Assessment (NAWQA) Program, initiated a topical study of Transport of Anthropogenic and Natural Contaminants (TANC) to PSW (public-supply wells). Local-scale and regional-scale TANC study areas were delineated within selected NAWQA study units for intensive study of processes effecting transport of contaminants to PSWs. ThiAuthorsMatthew K. Landon, Brian R. Clark, Peter B. McMahon, Virginia L. McGuire, Michael J. TurcoSimulated response of water quality in public supply wells to land use change
Understanding how changes in land use affect water quality of public supply wells (PSW) is important because of the strong influence of land use on water quality, the rapid pace at which changes in land use are occurring in some parts of the world, and the large contribution of groundwater to the global water supply. In this study, groundwater flow models incorporating particle tracking and reactiAuthorsP. B. McMahon, K.R. Burow, L. J. Kauffman, S. M. Eberts, J.K. Böhlke, J.J. GurdakSource and transport controls on the movement of nitrate to public supply wells in selected principal aquifers of the United States
In 2003–2005, systematic studies in four contrasting hydrogeologic settings were undertaken to improve understanding of source and transport controls on nitrate movement to public supply wells (PSW) in principal aquifers of the United States. Chemical, isotopic, and age tracer data show that agricultural fertilizers and urban septic leachate were the primary sources of large nitrate concentrationsAuthorsP. B. McMahon, J.K. Böhlke, L. J. Kauffman, K.L. Kipp, M.K. Landon, C. A. Crandall, K.R. Burow, C. J. BrownPotential for 4-n-nonylphenol biodegradation in stream sediments
The potential for in situ biodegradation of 4-nonylphenol (4-NP) was investigated in three hydrologically distinct streams impacted by wastewater treatment plants (WWTPs) in the United States. Microcosms were prepared with sediments from each site and amended with [U-ring-14C]4-n-nonylphenol (4-n-NP) as a model test substrate. Microcosms prepared with sediment collected upstream of the WWTP outfalAuthorsP. M. Bradley, L. B. Barber, D.W. Kolpin, P. B. McMahon, F. H. Chapelle - News