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P. F. Frenzel

Publications and source records attributed to P. F. Frenzel.

12 recordsLinked to original sources
USGS2014

A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch

Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch 1,2,3,4 . However, the same thermokarst lakes can also sequester carbon 5 , and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000   years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47±10 grams of carbon per square metre per year; mean±standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears 7,8,9 , potentially negating the climate stabilization provided by thermokarst lakes during the late Holocene.

Nature↗
USGS1999

Geologic and hydrologic data for the municipal solid waste landfill facility, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso County, Texas

Geologic and hydrologic data for the Municipal Solid Waste Landfill Facility on the U.S. Army Air Defense Artillery Center and Fort Bliss in El Paso County, Texas, were collected by the U.S. Geological Survey in cooperation with the U.S. Department of the Army. The 106.03-acre landfill has been in operation since January 1974. The landfill contains household refuse, Post solid wastes, bulky items, grass and tree trimmings from family housing, refuse from litter cans, construction debris, classified waste (dry), dead animals, asbestos, and empty oil cans. The depth of the filled areas is about 30 feet and the cover, consisting of locally derived material, is 2 to 3 feet thick. Geologic and hydrologic data were collected at or adjacent to the landfill during (1) drilling of 10 30- to 31-foot boreholes that were completed with gas-monitoring probes, (2) drilling of a 59-foot borehole, (3) drilling of a 355-foot borehole that was completed as a ground-water monitoring well, and (4) in situ measurements made on the landfill cover. After completion, the gas- monitoring probes were monitored on a quarterly basis (1 year total) for gases generated by the landfill. Water samples were collected from the ground-water monitoring well for chemical analysis. Data collection is divided into two elements: geologic data and hydrologic data. Geologic data include lithologic descriptions of cores and cuttings, geophysical logs, soil- gas and ambient-air analyses, and chemical analyses of soil. Hydrologic data include physical properties, total organic carbon, and pH of soil and sediment samples; soil-water chloride and soil-moisture analyses; physical properties of the landfill cover; measurements of depth to ground water; and ground-water chemical analyses. Interpretation of data is not included in this report.

Texas↗
USGS1995

Listings of model input and selected output values for the simulation of ground-water flow near Los Alamos, North-central New Mexico

This report contains listings of model input and selected output values for the simulation of ground-water flow near Los Alamos, north- central New Mexico. This simulation was developed by the U.S. Geological Survey in cooperation with Los Alamos National Laboratory (Frenzel, P.F., 1995, Geohydrology and simulation of ground-water flow near Los Alamos, north-central New Mexico: U.S. Geological Survey Water-Resources Investigations Report 95-4091). The simulation used the U.S. Geological Survey modular flow model code (McDonald, M.G., and Harbaugh, A.W., 1988, A modular three-dimensional finite-difference ground-water flow model: Techniques of Water-Resources Investigations of the United States Geological Survey, book 6, chap. A1). The listings in this report are in compressed format on a 1.44-megabyte IBM-PC1 compatible floppy disk. Software is included for decompression to ASCII format.

Open-File Report↗
USGS1995

Geohydrology and simulation of ground-water flow near Los Alamos, north-central New Mexico

An existing model was modified in recognition of new geohydrologic interpretations and adjusted to simulate hydrographs in well fields in the Los Alamos area. Hydraulic-head drawdowns at the Buckman well field resulting from two projected ground-water-withdrawal alternatives were estimated with the modified model. The Chaquehui formation (informal usage) is the main new feature of recent hydrologic interpretations for the Los Alamos area. The Chaquehui occupies a 'channel' that was eroded or faulted into the Tesuque Formation, and the Chaquehui is more permeable than the Tesuque. The Chaquehui is a major producing zone in the Pajarito Mesa well field and to a lesser extent in the Guaje well field. Model modification included splitting the four layers of the McAda-Wasiolek model (McAda, D.P., and Wasiolek, Maryann, 1988, Simulation of the regional geohydrology of the Tesuque aquifer system near Santa Fe, New Mexico: U.S. Geological Survey Water- Resources Investigations Report 87-4056, 71 p.) into eight layers to better simulate vertical ground-water movement. Other model modifications were limited as much as possible to the area of interest near Los Alamos and consisted mainly of adjusting hydraulic-conductivity values representing the Tesuque Formation, Chaquehui formation (informal usage), and Puye Formation, and adjusting simulated recharge along the Pajarito Fault Zone west of Los Alamos. Adjustments were based mainly on simulation of fluctuations in measured hydraulic heads near Los Alamos. Two possible alternative plans for replacing Guaje well field production were suggested by Los Alamos National Laboratory. In the first plan (Guaje alternative), the Guaje field would be renewed with four new wells replacing the existing production wells in the Guaje field. In the second plan (Pajarito-Otowi alternative), the Guaje well field would be retired and its former production would be made up by additional withdrawals from the Pajarito Mesa and Otowi well fields. A projection for each of these alternatives was made through 2012 using the new eight- layer model. In the Guaje field, projected hydraulic heads at the end of 2012 were as much as 50 feet lower with the Guaje alternative; in the Pajarito Mesa field, hydraulic heads were as much as 12 feet higher with the Guaje alternative. At the western end of the Los Alamos well field, projected hydraulic heads were about 20 feet higher with the Guaje alternative; at the eastern end of the Los Alamos field, the difference between alternatives was much less. At the Buckman field, projected hydraulic heads were about 2 feet higher with the Guaje alternative because the Buckman field is closer to the Pajarito Mesa field than to the Guaje field. Ways of improving the understanding of the flow system include developing a more accurate representation of the structure and extent of the Tesuque Formation, Chaquehui formation, and Puye Formation of the Santa Fe Group and obtaining more detailed geologic and hydrologic data for the Chaquehui and Puye. Data that describe water chemistry, hydraulic head, and degree of saturation would be valuable for determining the location and quantity of recharge on the Pajarito Plateau, especially along the west side of the Plateau and in canyon bottoms. Chloride concentrations in soil at the top of the Bandelier Tuff could be used to verify the concept that evapotranspiration accounts for nearly all precipitation over a large area of the plateau.

Water-Resources Investigations Report↗
USGS1983

Simulated changes in ground-water levels related to proposed development of Federal coal leases, San Juan Basin New Mexico

The effects of coal-related ground-water withdrawals on potentiometric surfaces of aquifers in the San Juan Basin, New Mexico, were estimated. A previously published steady-state finite-difference digital model was converted to a transient-state model by changing boundary conditions and adding storage coefficients. No calibration of the transient-state model was attempted. Predicted drawdowns with a minimum amount of coal development combined with other kinds of development were as great as 2,000 feet. As much as 300 feet of additional drawdown were simulated for the maximum amount of coal development. Drawdowns near pumping wells are not predicted. (USGS)

Open-File Report↗
USGS1982

Estimates of vertical hydraulic conductivity and regional ground-water flow rates in rocks of Jurassic and Cretaceous age, San Juan Basin, New Mexico and Colorado

The San Juan structural basin northwestern New Mexico was modeled in three dimensions using a finite-difference, steady-state model. The modeled space was divided into seven layers of square prisms that were 6 miles on a side in the horizontal directions. In the vertical direction, the layers of prisms ranged in thickness from 300 to 1,500 feet. The model included the geologic section between the base of the Entrada Sandstone and the top of Mesaverde Group. Principal aquifers in this section are mostly confined and include the Entrada Sandstone, the Westwater Canyon Member of the Morrison Formation , and the Gallup Sandstone. Values for vertical hydraulic conductivities from 10 to the minus 12th power to 10 to the minus 11th power feet per second for the confining layers gave a good simulation of head differences between layers, but a sensitivity analysis indicated that these values could be between 10 and 100 times greater. The model-derived steady-state flow was about 30 cubic feet per second. About one-half of the flow was in the San Juan River drainage basin about one-third in the Rio Grande drainage basin, and one-sixth in the Puerco River drainage basin. (USGS)

Water-Resources Investigations Report↗
USGS1980

A computer program for simulating geohydrologic systems in three dimensions

This document is directed toward individuals who wish to use a computer program to simulate ground-water flow in three dimensions. The strongly implicit procedure (SIP) numerical method is used to solve the set of simultaneous equations. New data processing techniques and program input and output options are emphasized. The quifer system to be modeled may be heterogeneous and anisotropic, and may include both artesian and water-table conditions. Systems which consist of well defined alternating layers of highly permeable and poorly permeable material may be represented by a sequence of equations for two dimensional flow in each of the highly permeable units. Boundaries where head or flux is user-specified may be irregularly shaped. The program also allows the user to represent streams as limited-source boundaries when the streamflow is small in relation to the hydraulic stress on the system. The data-processing techniques relating to ' cube ' input and output, to swapping of layers, to restarting of simulation, to free-format NAMELIST input, to the details of each sub-routine 's logic, and to the overlay program structure are discussed. The program is capable of processing large models that might overflow computer memories with conventional programs. Detailed instructions for selecting program options, for initializing the data arrays, for defining ' cube ' output lists and maps, and for plotting hydrographs of calculated and observed heads and/or drawdowns are provided. Output may be restricted to those nodes of particular interest, thereby reducing the volumes of printout for modelers, which may be critical when working at remote terminals. ' Cube ' input commands allow the modeler to set aquifer parameters and initialize the model with very few input records. Appendixes provide instructions to compile the program, definitions and cross-references for program variables, summary of the FLECS structured FORTRAN programming language, listings of the FLECS and FORTRAN source code, and samples of input and output for example simulations. (USGS)

Open-File Report↗