Peter B McMahon (Former Employee)
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 118
Climate variability controls on unsaturated water and chemical movement, High Plains aquifer, USA Climate variability controls on unsaturated water and chemical movement, High Plains aquifer, USA
Responses in the vadose zone and groundwater to interannual, interdecadal, and multidecadal climate variability have important implications for groundwater resource sustainability, yet they are poorly documented and not well understood in most aquifers of the USA. This investigation systematically examines the role of interannual to multidecadal climate variability on groundwater levels...
Authors
J.J. Gurdak, R. T. Hanson, P.B. McMahon, B. W. Bruce, J.E. McCray, G.D. Thyne, R.C. Reedy
Storage and transit time of chemicals in thick unsaturated zones under rangeland and irrigated cropland, High Plains, United States Storage and transit time of chemicals in thick unsaturated zones under rangeland and irrigated cropland, High Plains, United States
In 2000-2002, three rangeland and six irrigated sites were instrumented to assess the storage and transit time of chemicals in thick (15 to 50 m) unsaturated zones (UZ) in the High Plains. These processes are likely to influence relations between land use and groundwater quality, yet they have not been documented systematically in the High Plains. Land use and climate were important...
Authors
P.B. McMahon, K.F. Dennehy, B. W. Bruce, J.K. Böhlke, R. L. Michel, J.J. Gurdak, D.B. Hurlbut
Regional patterns in the isotopic composition of natural and anthropogenic nitrate in groundwater, High Plains, U.S.A. Regional patterns in the isotopic composition of natural and anthropogenic nitrate in groundwater, High Plains, U.S.A.
Mobilization of natural nitrate (NO3-) deposits in the subsoil by irrigation water in arid and semiarid regions has the potential to produce large groundwater NO3- concentrations. The use of isotopes to distinguish between natural and anthropogenic NO3- sources in these settings could be complicated by the wide range in δ15N values of natural NO3-. An ∼10 000 year record of paleorecharge...
Authors
P.B. McMahon, J.K. Böhlke
Use of isotopes, age-dating, and numerical simulation to evaluate source histories and transport of NO3- to public supply wells in principal aquifers of the United States Use of isotopes, age-dating, and numerical simulation to evaluate source histories and transport of NO3- to public supply wells in principal aquifers of the United States
No abstract available.
Authors
P.B. McMahon, J.K. Bohlke, C. Brown, K. Burow, C. A. Crandall, Matthew K. Landon
Vertical gradients in water chemistry and age in the southern High Plains Aquifer, Texas, 2002 Vertical gradients in water chemistry and age in the southern High Plains Aquifer, Texas, 2002
The southern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of New Mexico and Texas. Despite the aquifer's importance to the overall economy of the southern High Plains, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S. Geological...
Authors
P.B. McMahon, J.K. Böhlke, T.M. Lehman
Geochemistry, radiocarbon ages, and paleorecharge conditions along a transect in the central High Plains aquifer, southwestern Kansas, USA Geochemistry, radiocarbon ages, and paleorecharge conditions along a transect in the central High Plains aquifer, southwestern Kansas, USA
Water samples from short-screen monitoring wells installed along a 90-km transect in southwestern Kansas were analyzed for major ions, trace elements, isotopes (H, B, C, N, O, S, Sr), and dissolved gases (He, Ne, N2, Ar, O2, CH4) to evaluate the geochemistry, radiocarbon ages, and paleorecharge conditions in the unconfined central High Plains aquifer. The primary reactions controlling...
Authors
P.B. McMahon, J.K. Böhlke, S. C. Christenson
Science and Products
Filter Total Items: 14
No Result Found
Filter Total Items: 118
Climate variability controls on unsaturated water and chemical movement, High Plains aquifer, USA Climate variability controls on unsaturated water and chemical movement, High Plains aquifer, USA
Responses in the vadose zone and groundwater to interannual, interdecadal, and multidecadal climate variability have important implications for groundwater resource sustainability, yet they are poorly documented and not well understood in most aquifers of the USA. This investigation systematically examines the role of interannual to multidecadal climate variability on groundwater levels...
Authors
J.J. Gurdak, R. T. Hanson, P.B. McMahon, B. W. Bruce, J.E. McCray, G.D. Thyne, R.C. Reedy
Storage and transit time of chemicals in thick unsaturated zones under rangeland and irrigated cropland, High Plains, United States Storage and transit time of chemicals in thick unsaturated zones under rangeland and irrigated cropland, High Plains, United States
In 2000-2002, three rangeland and six irrigated sites were instrumented to assess the storage and transit time of chemicals in thick (15 to 50 m) unsaturated zones (UZ) in the High Plains. These processes are likely to influence relations between land use and groundwater quality, yet they have not been documented systematically in the High Plains. Land use and climate were important...
Authors
P.B. McMahon, K.F. Dennehy, B. W. Bruce, J.K. Böhlke, R. L. Michel, J.J. Gurdak, D.B. Hurlbut
Regional patterns in the isotopic composition of natural and anthropogenic nitrate in groundwater, High Plains, U.S.A. Regional patterns in the isotopic composition of natural and anthropogenic nitrate in groundwater, High Plains, U.S.A.
Mobilization of natural nitrate (NO3-) deposits in the subsoil by irrigation water in arid and semiarid regions has the potential to produce large groundwater NO3- concentrations. The use of isotopes to distinguish between natural and anthropogenic NO3- sources in these settings could be complicated by the wide range in δ15N values of natural NO3-. An ∼10 000 year record of paleorecharge...
Authors
P.B. McMahon, J.K. Böhlke
Use of isotopes, age-dating, and numerical simulation to evaluate source histories and transport of NO3- to public supply wells in principal aquifers of the United States Use of isotopes, age-dating, and numerical simulation to evaluate source histories and transport of NO3- to public supply wells in principal aquifers of the United States
No abstract available.
Authors
P.B. McMahon, J.K. Bohlke, C. Brown, K. Burow, C. A. Crandall, Matthew K. Landon
Vertical gradients in water chemistry and age in the southern High Plains Aquifer, Texas, 2002 Vertical gradients in water chemistry and age in the southern High Plains Aquifer, Texas, 2002
The southern High Plains aquifer is the primary source of water used for domestic, industrial, and irrigation purposes in parts of New Mexico and Texas. Despite the aquifer's importance to the overall economy of the southern High Plains, fundamental ground-water characteristics, such as vertical gradients in water chemistry and age, remain poorly defined. As part of the U.S. Geological...
Authors
P.B. McMahon, J.K. Böhlke, T.M. Lehman
Geochemistry, radiocarbon ages, and paleorecharge conditions along a transect in the central High Plains aquifer, southwestern Kansas, USA Geochemistry, radiocarbon ages, and paleorecharge conditions along a transect in the central High Plains aquifer, southwestern Kansas, USA
Water samples from short-screen monitoring wells installed along a 90-km transect in southwestern Kansas were analyzed for major ions, trace elements, isotopes (H, B, C, N, O, S, Sr), and dissolved gases (He, Ne, N2, Ar, O2, CH4) to evaluate the geochemistry, radiocarbon ages, and paleorecharge conditions in the unconfined central High Plains aquifer. The primary reactions controlling...
Authors
P.B. McMahon, J.K. Böhlke, S. C. Christenson