Peter B McMahon (Former Employee)
Science and Products
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Potential for 4-n-nonylphenol biodegradation in stream sediments 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...
Authors
P. M. Bradley, L. Barber, D.W. Kolpin, P.B. McMahon, F. Chapelle
Redox processes and water quality of selected principal aquifer systems Redox processes and water quality of selected principal aquifer systems
Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen...
Authors
P.B. McMahon, F. Chapelle
Water-Quality Assessment of the High Plains Aquifer, 1999-2004 Water-Quality Assessment of the High Plains Aquifer, 1999-2004
Water quality of the High Plains aquifer was assessed for the period 1999-2004 as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. This effort represents the first systematic regional assessment of water quality in this nationally important aquifer. A stratified, nested group of studies was designed to assess linkages between the quality of water...
Authors
Peter McMahon, Kevin Dennehy, Breton Bruce, Jason J. Gurdak, Sharon Qi
Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003 Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003
The northern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of Colorado, Kansas, Nebraska, South Dakota, and Wyoming. Despite the aquifer’s importance to the regional economy, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S...
Authors
P.B. McMahon, J.K. Böhlke, C. Carney
Nitrous oxide fluxes from cultivated areas and rangeland: U.S. High Plains Nitrous oxide fluxes from cultivated areas and rangeland: U.S. High Plains
Concentration profiles of N2O, a greenhouse gas, and the conservative trace gases SF6 and the chlorofluorocarbons CFC-11, CFC-12, CFC-113, and were measured periodically through thick vadose zones at nine sites in the U.S. High Plains. The CFC and SF6 measurements were used to calibrate a one-dimensional gas diffusion model, using the parameter identification program UCODE. The...
Authors
Edwin Weeks, Peter McMahon
Biotransformation of caffeine, cotinine, and nicotine in stream sediments: Implications for use as wastewater indicators Biotransformation of caffeine, cotinine, and nicotine in stream sediments: Implications for use as wastewater indicators
Microbially catalyzed cleavage of the imadazole ring of caffeine was observed in stream sediments collected upstream and downstream of municipal wastewater treatment plants (WWTP) in three geographically separate stream systems. Microbial demethylation of the N-methyl component of cotinine and its metabolic precursor, nicotine, also was observed in these sediments. These findings...
Authors
Paul Bradley, Larry Barber, Dana Kolpin, Peter McMahon, Francis Chapelle
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 118
Potential for 4-n-nonylphenol biodegradation in stream sediments 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...
Authors
P. M. Bradley, L. Barber, D.W. Kolpin, P.B. McMahon, F. Chapelle
Redox processes and water quality of selected principal aquifer systems Redox processes and water quality of selected principal aquifer systems
Reduction/oxidation (redox) conditions in 15 principal aquifer (PA) systems of the United States, and their impact on several water quality issues, were assessed from a large data base collected by the National Water-Quality Assessment Program of the USGS. The logic of these assessments was based on the observed ecological succession of electron acceptors such as dissolved oxygen...
Authors
P.B. McMahon, F. Chapelle
Water-Quality Assessment of the High Plains Aquifer, 1999-2004 Water-Quality Assessment of the High Plains Aquifer, 1999-2004
Water quality of the High Plains aquifer was assessed for the period 1999-2004 as part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program. This effort represents the first systematic regional assessment of water quality in this nationally important aquifer. A stratified, nested group of studies was designed to assess linkages between the quality of water...
Authors
Peter McMahon, Kevin Dennehy, Breton Bruce, Jason J. Gurdak, Sharon Qi
Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003 Vertical gradients in water chemistry and age in the Northern High Plains Aquifer, Nebraska, 2003
The northern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of Colorado, Kansas, Nebraska, South Dakota, and Wyoming. Despite the aquifer’s importance to the regional economy, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S...
Authors
P.B. McMahon, J.K. Böhlke, C. Carney
Nitrous oxide fluxes from cultivated areas and rangeland: U.S. High Plains Nitrous oxide fluxes from cultivated areas and rangeland: U.S. High Plains
Concentration profiles of N2O, a greenhouse gas, and the conservative trace gases SF6 and the chlorofluorocarbons CFC-11, CFC-12, CFC-113, and were measured periodically through thick vadose zones at nine sites in the U.S. High Plains. The CFC and SF6 measurements were used to calibrate a one-dimensional gas diffusion model, using the parameter identification program UCODE. The...
Authors
Edwin Weeks, Peter McMahon
Biotransformation of caffeine, cotinine, and nicotine in stream sediments: Implications for use as wastewater indicators Biotransformation of caffeine, cotinine, and nicotine in stream sediments: Implications for use as wastewater indicators
Microbially catalyzed cleavage of the imadazole ring of caffeine was observed in stream sediments collected upstream and downstream of municipal wastewater treatment plants (WWTP) in three geographically separate stream systems. Microbial demethylation of the N-methyl component of cotinine and its metabolic precursor, nicotine, also was observed in these sediments. These findings...
Authors
Paul Bradley, Larry Barber, Dana Kolpin, Peter McMahon, Francis Chapelle