Peter B McMahon (Former Employee)
Science and Products
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Filter Total Items: 118
Hydrologic and geochemical effects on oxygen uptake in bottom sediments of an effluent-dominated river Hydrologic and geochemical effects on oxygen uptake in bottom sediments of an effluent-dominated river
More than 95% of the water in the South Platte River downstream from the largest wastewater treatment plant serving the metropolitan Denver, Colorado, area consists of treated effluent during some periods of low flow. Fluctuations in effluent-discharge rates caused daily changes in river stage that promoted exchange of water between the river and bottom sediments. Groundwater discharge
Authors
P.B. McMahon, J.A. Tindall, J.A. Collins, K.J. Lull, J.R. Nuttle
Water-quality assessment of the South Platte River basin, Colorado, Nebraska, and Wyoming: Analysis of available nutrient, suspended-sediment, and pesticide data, water years 1980-92 Water-quality assessment of the South Platte River basin, Colorado, Nebraska, and Wyoming: Analysis of available nutrient, suspended-sediment, and pesticide data, water years 1980-92
Nutrient, suspended-sediment, and pesticide data from surface- and ground-water sites in the South Platte River Basin for water years 1980-92 were compiled, screened, and interpreted. This activity is part of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program. The analysis of existing water-quality data provides a perspective on recent water-quality conditions...
Authors
K.F. Dennehy, D. Litke, P.B. McMahon, J. S. Heiny, C. Tate
Nitrate transport and transformation processes in unsaturated porous media Nitrate transport and transformation processes in unsaturated porous media
A series of experiments was conducted on two contrasting agricultural soils to observe the influence of soil texture, preferential flow, and plants on nitrate transport and denitrification under unsaturated conditions. Calcium nitrate fertilizer was applied to the surface of four large undisturbed soil cores (30 cm diameter by 40 cm height). Two of the cores were a structured clay...
Authors
James Tindall, Robin Petrusak, Peter McMahon
Deducing the distribution of terminal electron-accepting processes in hydrologically diverse groundwater systems Deducing the distribution of terminal electron-accepting processes in hydrologically diverse groundwater systems
The distribution of microbially mediated terminal electron-accepting processes (TEAPs( was investigated in four hydrologically diverse groundwater systems by considering patterns of electron acceptor (nitrate, sulfate) consumption, intermediate product (hydrogen (H2)) concentrations, and final product (ferrous iron, sulfide, and methane) production. In each hydrologic system a...
Authors
Francis Chapelle, Peter McMahon, Neil Dubrovsky, Roger F. Fujii, Edward Oaksford, Don Vroblesky
Some bacteria are beneficial! Some bacteria are beneficial!
Most people would agree that bacteria usually spell trouble where the quality of drinking water is con cerned. However, recent studies conducted by the U.S. Geological Survey (USGS) under the National Water-Quality Assessment (NAWQA) program have shown that some bacteria can improve the quality of water.
Authors
Peter McMahon
Effect of ground-water/surface-water interactions on nitrate concentrations in discharge from the South Platte River alluvial aquifer, Colorado Effect of ground-water/surface-water interactions on nitrate concentrations in discharge from the South Platte River alluvial aquifer, Colorado
Concentrations of dissolved nitrate in recharge-area water from a 200-km2 segment of the South Platte River alluvial aquifer near Greeley, Colorado, range from less than 0.1 to 58 mg/l as nitrogen, and the median concentration is 26 mg/l as nitrogen. Hydraulic-head data indicate that this nitrate-enriched ground water move toward the South Platte River. However, the median concentration...
Authors
P.B. McMahon, J.K. Böhlke
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 118
Hydrologic and geochemical effects on oxygen uptake in bottom sediments of an effluent-dominated river Hydrologic and geochemical effects on oxygen uptake in bottom sediments of an effluent-dominated river
More than 95% of the water in the South Platte River downstream from the largest wastewater treatment plant serving the metropolitan Denver, Colorado, area consists of treated effluent during some periods of low flow. Fluctuations in effluent-discharge rates caused daily changes in river stage that promoted exchange of water between the river and bottom sediments. Groundwater discharge
Authors
P.B. McMahon, J.A. Tindall, J.A. Collins, K.J. Lull, J.R. Nuttle
Water-quality assessment of the South Platte River basin, Colorado, Nebraska, and Wyoming: Analysis of available nutrient, suspended-sediment, and pesticide data, water years 1980-92 Water-quality assessment of the South Platte River basin, Colorado, Nebraska, and Wyoming: Analysis of available nutrient, suspended-sediment, and pesticide data, water years 1980-92
Nutrient, suspended-sediment, and pesticide data from surface- and ground-water sites in the South Platte River Basin for water years 1980-92 were compiled, screened, and interpreted. This activity is part of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program. The analysis of existing water-quality data provides a perspective on recent water-quality conditions...
Authors
K.F. Dennehy, D. Litke, P.B. McMahon, J. S. Heiny, C. Tate
Nitrate transport and transformation processes in unsaturated porous media Nitrate transport and transformation processes in unsaturated porous media
A series of experiments was conducted on two contrasting agricultural soils to observe the influence of soil texture, preferential flow, and plants on nitrate transport and denitrification under unsaturated conditions. Calcium nitrate fertilizer was applied to the surface of four large undisturbed soil cores (30 cm diameter by 40 cm height). Two of the cores were a structured clay...
Authors
James Tindall, Robin Petrusak, Peter McMahon
Deducing the distribution of terminal electron-accepting processes in hydrologically diverse groundwater systems Deducing the distribution of terminal electron-accepting processes in hydrologically diverse groundwater systems
The distribution of microbially mediated terminal electron-accepting processes (TEAPs( was investigated in four hydrologically diverse groundwater systems by considering patterns of electron acceptor (nitrate, sulfate) consumption, intermediate product (hydrogen (H2)) concentrations, and final product (ferrous iron, sulfide, and methane) production. In each hydrologic system a...
Authors
Francis Chapelle, Peter McMahon, Neil Dubrovsky, Roger F. Fujii, Edward Oaksford, Don Vroblesky
Some bacteria are beneficial! Some bacteria are beneficial!
Most people would agree that bacteria usually spell trouble where the quality of drinking water is con cerned. However, recent studies conducted by the U.S. Geological Survey (USGS) under the National Water-Quality Assessment (NAWQA) program have shown that some bacteria can improve the quality of water.
Authors
Peter McMahon
Effect of ground-water/surface-water interactions on nitrate concentrations in discharge from the South Platte River alluvial aquifer, Colorado Effect of ground-water/surface-water interactions on nitrate concentrations in discharge from the South Platte River alluvial aquifer, Colorado
Concentrations of dissolved nitrate in recharge-area water from a 200-km2 segment of the South Platte River alluvial aquifer near Greeley, Colorado, range from less than 0.1 to 58 mg/l as nitrogen, and the median concentration is 26 mg/l as nitrogen. Hydraulic-head data indicate that this nitrate-enriched ground water move toward the South Platte River. However, the median concentration...
Authors
P.B. McMahon, J.K. Böhlke