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Articles 31 - 60 of 102
Full-Text Articles in Physical Sciences and Mathematics
Multivariate Correlation Between Concentrations Of Selected Herbicides And Derivatives In Outflows From Selected U.S. Midwestern Reservoirs, R. Tauler, D. Barcelo, E. Michael Thurman
Multivariate Correlation Between Concentrations Of Selected Herbicides And Derivatives In Outflows From Selected U.S. Midwestern Reservoirs, R. Tauler, D. Barcelo, E. Michael Thurman
United States Geological Survey: Staff Publications
Multivariate correlations between the concentrations of selected herbicides and herbicide derivatives in outflows from selected reservoirs in the Midwestern United States for April 1992 through September 1993 were investigated using principal component analysis (PCA) and multivariate curve resolution (MCR). Two independent sources for alachlor ethanesulfonic acid, one major source related to spring flush and seasonal runoff and another minor source related to groundwater, were identified using PCA. Results of MCR provided a semiquantitative interpretation of the environmental sources of the observed herbicide concentrations in reservoir outflows and allowed the examination of their temporal and geographical distributions. Samples with higher herbicide …
Chronology And Geochemistry Of Late Holocene Eolian Deposits In The Brandon Sand Hills, Manitoba, Canada, Stephen A. Wolfe, Daniel R. Muhs, Peter P. David, John P. Mcgeehin
Chronology And Geochemistry Of Late Holocene Eolian Deposits In The Brandon Sand Hills, Manitoba, Canada, Stephen A. Wolfe, Daniel R. Muhs, Peter P. David, John P. Mcgeehin
United States Geological Survey: Staff Publications
Accelerator mass spectrometry and conventional radiocarbon age determinations of organic matter from paleosols indicate that the Brandon Sand Hills area of southern Manitoba has been subjected to recurrent intervals of eolian activity in the past 5000 years. Although precise regional correlations are precluded by dating uncertainties, periods of most notable paleosol development occurred around 2300 to 2000, 1400 to 1000, and 600 to 500 cal yr BP with eolian activity occurring before and after each of these periods. Episodes of eolian activity may correspond to periods of regional drought, whereas paleosols mark periods of increased moisture availability and stabilization by …
Nest Predation On Black-Tailed Prairie Dog Colonies, Bruce Baker, Thomas R. Stanley, Glenn Plumb
Nest Predation On Black-Tailed Prairie Dog Colonies, Bruce Baker, Thomas R. Stanley, Glenn Plumb
United States Geological Survey: Staff Publications
Nest predation is the principal cause of mortality for many grassland birds. Predation rates may be higher on prairie dog colonies because they may have less available nesting cover and may increase predator abundance. We compared 14-day nest predation rates for 1,764 artificial nests on 102 black-tailed prairie dog (Cynovnys ludovicianus) colonies and their paired off-colony sites (similar habitat lacking prairie dogs) from 14 May to 26 June 1998 in South Dakota and Wyoming. Predation rates on colonies (66.2 ± 2.2%; x ± SE) were 29.5% higher than at off-colony sites (51.1 ± 2.7%). Nesting cover on colonies …
Expression Of A Dominant-Negative Mutant Of P21ras Inhibits Induction Of Nitric Oxide Synthase And Activation Of Nuclear Factor-Kb In Primary Astrocytes, Kalipada Pahan, Xiaojuan Lu, Michael J. Mckinney, Charles Wood, Faruk G. Sheikh, John R. Raymond
Expression Of A Dominant-Negative Mutant Of P21ras Inhibits Induction Of Nitric Oxide Synthase And Activation Of Nuclear Factor-Kb In Primary Astrocytes, Kalipada Pahan, Xiaojuan Lu, Michael J. Mckinney, Charles Wood, Faruk G. Sheikh, John R. Raymond
School of Biological Sciences: Faculty Publications
The present study underlines the importance of p21ras in regulating the inducible nitric oxide synthase (iNOS) in primary astrocytes. Bacterial lipopolysaccharides induced the GTP loading of p21ras, and the expression of a dominant-negative mutant of p21ras (Dp21ras) inhibited lipopolysaccharide-induced GTP loading in rat primary astrocytes. To delineate the role of p21ras in the induction of iNOS, we examined the effect of Dp21ras on the expression of iNOS and the production of nitric oxide. It is interesting that expression of Dp21ras markedly inhibited the production of nitric oxide and the expression of iNOS in lipopolysaccharide- and pro-inflammatory cytokine (tumor necrosis factor-a, …
Aquatic Dissipation Of The Herbicide Triclopyr In Lake Minnetonka, Minnesota, Kurt D. Getsinger, David G. Petty, John D. Madsen, John G. Skogerboe, Bruce A. Houtman, William T. Haller, Alison M. Fox
Aquatic Dissipation Of The Herbicide Triclopyr In Lake Minnetonka, Minnesota, Kurt D. Getsinger, David G. Petty, John D. Madsen, John G. Skogerboe, Bruce A. Houtman, William T. Haller, Alison M. Fox
US Army Corps of Engineers
A study of the aquatic fate of the triethylamine salt of triclopyr (3,5,6-trichloro-2- pyridinyloxyacetic acid) was conducted in three bays of Lake Minnetonka, Minnesota. Triclopyr is under review by the US Environmental Protection Agency as a selective aquatic herbicide. The primary purpose of this study was to determine dissipation rates of the parent active ingredient, triclopyr, and its major metabolites, 3,5,6-trichloropyridinol (TCP) and 3,5,6-trichloro-2-methoxypyridine (TMP) in selected matrices including water, sediment, plants, finfish and shellfish. Two 6.5- ha plots dominated by the weedy species Eurasian watermilfoil (Myriophyllum spicatum L) were treated with triclopyr-triethylammonum at a rate of 2.5mg AE liter …
Hayes County Test Hole Logs, Duane A. Eversoll
Hayes County Test Hole Logs, Duane A. Eversoll
Conservation and Survey Division
No abstract provided.
Oregon Trail/Other Points Of Interest In Nebraska, University Of Nebraska - Lincoln
Oregon Trail/Other Points Of Interest In Nebraska, University Of Nebraska - Lincoln
Conservation and Survey Division
No abstract provided.
Morphology And Taxonomic Position Of The Late Cretaceous Diatom Genus Pomphodiscus Barker & Meakin, Vladimir A. Nikolaev, David M. Harwood
Morphology And Taxonomic Position Of The Late Cretaceous Diatom Genus Pomphodiscus Barker & Meakin, Vladimir A. Nikolaev, David M. Harwood
Department of Earth and Atmospheric Sciences: Faculty Publications
Results from our investigation of Upper Cretaceous diatoms from the Marca Shale Member of the Moreno Shale in California and from Ocean Drilling Program (ODP) Hole 748C on the Kerguelen Plateau ,Southern Indian Ocean enable a clarification of the taxonomic position of several diatoms. Differences in areola structure ,a primary and conservative character of the diatom valve, are used to separate diatoms recently included in the genus Benetorus. We resurrect he genus Pomphodiscusto include species with locular areolae, a central rimoportula ,and a central inflated chamber .We propose the new species Pomphodiscusk erguelensisn. sp. and new combination Pomphodiscusc …
Kinematic Structure Of Minipermeameter Flow, Daniel M. Tartakovsky, J. David Moulton, Vitaly A. Zlotnik
Kinematic Structure Of Minipermeameter Flow, Daniel M. Tartakovsky, J. David Moulton, Vitaly A. Zlotnik
Department of Earth and Atmospheric Sciences: Faculty Publications
Minipermeameters are rapidly becoming a popular tool for collecting localized
measurements of permeability in both laboratory and field studies. While one of the main advantages of minipermeameters is their ability to collect data on various support volumes, there have been only limited attempts to analyze their size and geometry. We define the support volume of minipermeameter measurements as a region containing 90% of the total gas flow, i.e., a region bounded by the 10% streamline. Using our new semianalytical solutions for the Stokes' stream function, we demonstrate that the support volume has a shape of the semitoroid adjacent to the …
Grassland Bird Use Of Conservation Reserve Program Fields In The Great Plains, Douglas H. Johnson
Grassland Bird Use Of Conservation Reserve Program Fields In The Great Plains, Douglas H. Johnson
Publications of the US Geological Survey
The area enrolled in the Conservation Reserve Program in the Great Plains is enormous: nearly 18 million acres, or more than 7 million hectares, in Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, and Texas. This change in land use has had a huge influence on grassland bird populations. Many, but certainly not all, grassland species flourish in CRP habitats. Responses to the program vary not only by species, but by region, year, vegetation composition in a field, and whether or not a field was hayed or grazed. Further, the large scale of CRP has allowed researchers to …
Mercury Bioaccumulation In Fish In A Region Affected By Historic Gold Mining: The South Yuba River, Deer Creek, And Bear River Watersheds, California, 1999, Jason T. May, Roger L. Hothem, Charles N. Alpers, Matthew A. Law
Mercury Bioaccumulation In Fish In A Region Affected By Historic Gold Mining: The South Yuba River, Deer Creek, And Bear River Watersheds, California, 1999, Jason T. May, Roger L. Hothem, Charles N. Alpers, Matthew A. Law
Publications of the US Geological Survey
Mercury that was used historically for gold recovery in mining areas of the Sierra Nevada continues to enter local and downstream water bodies, including the Sacramento–San Joaquin Delta and the San Francisco Bay of northern California. Methylmercury is of particular concern because it is the most prevalent form of mercury in fish and is a potent neurotoxin that bioaccumulates at successive trophic levels within food webs. In April 1999, the U.S. Geological Survey, in cooperation with several other agencies—the Forest Service (U.S. Department of Agriculture), the Bureau of Land Management, the U.S. Environmental Protection Agency, the California State Water Resources …
Metals Transport In The Sacramento River, California, 1996–1997 Volume 2: Interpretation Of Metal Loads, Charles N. Alpers, Ronald C. Antweiler, Howard E. Taylor, Peter D. Dileanis, Joseph L. Domagalski
Metals Transport In The Sacramento River, California, 1996–1997 Volume 2: Interpretation Of Metal Loads, Charles N. Alpers, Ronald C. Antweiler, Howard E. Taylor, Peter D. Dileanis, Joseph L. Domagalski
Publications of the US Geological Survey
Metals transport in the Sacramento River, northern California, from July 1996 to June 1997 was evaluated in terms of metal loads from sam-ples of water and suspended colloids that were collected on up to six occasions at 13 sites in the Sacramento River Basin. Four of the sampling periods (July, September, and November 1996; and May–June 1997) took place during relatively low-flow conditions and two sampling periods (December 1996 and January 1997) took place during high-flow and flooding conditions, respec-tively. This study focused primarily on loads of cadmium, copper, lead, and zinc, with secondary emphasis on loads of aluminum, iron, …
Mercury Contamination From Historic Gold Mining In California, Charles N. Alpers, Michael P. Hunerlach
Mercury Contamination From Historic Gold Mining In California, Charles N. Alpers, Michael P. Hunerlach
Publications of the US Geological Survey
Mercury contamination from historic gold mines represents a potential risk to human health and the environment. This fact sheet provides background information on the use of mercury in historic gold mining and processing operations in California, and describes a new USGS project that addresses the potential risks associated with mercury from these sources, with emphasis on historic hydraulic mining areas. Miners used mercury (quicksilver) to recover gold throughout the western United States at both placer (alluvial) and hardrock (lode) mines. The vast majority of mercury lost to the environment in California was from placer-gold mines, which used hydraulic, drift, and …
Metals Transport In The Sacramento River, California, 1996–1997 Volume 1: Methods And Data, Charles N. Alpers, Howard E. Taylor, Joseph L. Domagalski
Metals Transport In The Sacramento River, California, 1996–1997 Volume 1: Methods And Data, Charles N. Alpers, Howard E. Taylor, Joseph L. Domagalski
Publications of the US Geological Survey
Metals transport in the Sacramento River, northern California, was evaluated on the basis of samples of water, suspended colloids, streambed sediment, and caddisfly larvae that were collected on one to six occasions at 19 sites in the Sacramento River Basin from July 1996 to June 1997. Four of the sampling periods (July, September, and November 1996; and May–June 1997) took place during relatively low-flow conditions and two sampling periods (December 1996 and January 1997) took place during high-flow and flooding conditions; respectively. Tangential-flow ultrafiltration with 10,000 nominal molecular weight limit, or daltons (0.005 micrometer equivalent), pore-size membranes was used to …
Land Cover Trends Dataset, 1973–2000, Christopher E. Soulard, William Acevedo, Roger F. Auch, Terry L. Sohl, Mark A. Drummond, Benjamin M. Sleeter, Daniel G. Sorenson, Steve Kambly, Tamara S. Wilson, Janis L. Taylor, Kristi L. Sayler, Michael P. Stier, Christopher A. Barnes, Steve C. Methven, Thomas R. Loveland, Rachel Headley, Mark S. Brooks
Land Cover Trends Dataset, 1973–2000, Christopher E. Soulard, William Acevedo, Roger F. Auch, Terry L. Sohl, Mark A. Drummond, Benjamin M. Sleeter, Daniel G. Sorenson, Steve Kambly, Tamara S. Wilson, Janis L. Taylor, Kristi L. Sayler, Michael P. Stier, Christopher A. Barnes, Steve C. Methven, Thomas R. Loveland, Rachel Headley, Mark S. Brooks
Publications of the US Geological Survey
The U.S. Geological Survey Land Cover Trends Project is releasing a 1973–2000 time-series land-use/land-cover dataset for the conterminous United States. The dataset contains 5 dates of land-use/land-cover data for 2,688 sample blocks randomly selected within 84 ecological regions. The nominal dates of the land-use/land-cover maps are 1973, 1980, 1986, 1992, and 2000. The land-use/land-cover maps were classified manually from Landsat Multispectral Scanner, Thematic Mapper, and Enhanced Thematic Mapper Plus imagery using a modified Anderson Level I classification scheme. The resulting land-use/land-cover data has a 60-meter resolution and the projection is set to Albers Equal-Area Conic, North American Datum of 1983. …
Fractured-Aquifer Hydrogeology From Geophysical Logs: Brunswick Group And Lockatong Formation, Pennsylvania, Roger H. Morin, Lisa A. Senior, Edward R. Decker
Fractured-Aquifer Hydrogeology From Geophysical Logs: Brunswick Group And Lockatong Formation, Pennsylvania, Roger H. Morin, Lisa A. Senior, Edward R. Decker
United States Geological Survey: Staff Publications
The Brunswick Group and the underlying Lockatong Formation are composed of lithified Mesozoic sediments that constitute part of the Newark Basin in southeastern Pennsylvania. These fractured rocks form an important regional aquifer that consists of gradational sequences of shale, siltstone, and sandstone, with fluid transport occurring primarily in fractures. An extensive suite of geophysical logs was obtained in seven wells located at the borough of Lansdale, Pennsylvania, in order to better characterize the areal hydrogeologic system and provide guidelines for the refinement of numerical ground water models. Six of the seven wells are approximately 120 m deep and the seventh …
Negative Ph And Extremely Acidic Mine Waters From Iron Mountain, California, Darrell Kirk Nordstrom, Charles N. Alpers, Carol J. Ptacek, David W. Blowes
Negative Ph And Extremely Acidic Mine Waters From Iron Mountain, California, Darrell Kirk Nordstrom, Charles N. Alpers, Carol J. Ptacek, David W. Blowes
United States Geological Survey: Staff Publications
Extremely acidic mine waters with pH values as low as -3.6, total dissolved metal concentrations as high as 200 g/L, and sulfate concentrations as high as 760 g/L, have been encountered underground in the Richmond Mine at Iron Mountain, CA. These are the most acidic waters known. The pH measurements were obtained by using the Pitzer method to define pH for calibration of glass membrane electrodes. The calibration of pH below 0.5 with glass membrane electrodes becomes strongly nonlinear but is reproducible to a pH as low as -4. Numerous efflorescent minerals were found forming from these acid waters. These …
Ecogeochemistry Of The Subsurface Food Web At Ph 0–2.5 In Iron Mountain, California, U.S.A., Eleanora I. Robbins, Teresa M. Rodgers, Charles N. Alpers, D. Kirk Nordstrom
Ecogeochemistry Of The Subsurface Food Web At Ph 0–2.5 In Iron Mountain, California, U.S.A., Eleanora I. Robbins, Teresa M. Rodgers, Charles N. Alpers, D. Kirk Nordstrom
United States Geological Survey: Staff Publications
Pyrite oxidation in the underground mining environment of Iron Mountain, California, has created the most acidic pH values ever reported in aquatic systems. Sulfate values as high as 120 000 mg 1-1 and iron as high as 27600mg 1-1 have been measured in the mine water, which also carries abundant other dissolved metals including Al, Zn, Cu, Cd, Mn, Sb and Pb. Extreme acidity and high metal concentrations apparently do not preclude the presence of an underground acidophilic food web, which has developed with bacterial biomass at the base and heliozoans as top predators. Slimes, oil-like films, flexible …
Natural And Anthropogenic Influences On The Distribution Of The Threatened Neosho Madtom In A Midwestern Warmwater Stream, Mark L. Wildhaber, Vernon M. Tabor, Daniel W. Mulhern, Kenneth L. Powell, Scott P. Sowa
Natural And Anthropogenic Influences On The Distribution Of The Threatened Neosho Madtom In A Midwestern Warmwater Stream, Mark L. Wildhaber, Vernon M. Tabor, Daniel W. Mulhern, Kenneth L. Powell, Scott P. Sowa
United States Geological Survey: Staff Publications
We attempted to discern the contributions of physical habitat, water chemistry, nutrients, and contaminants from historic lead-zinc mining activities on the riffle-dwelling benthic fish community of the Spring River, a mid western warm water stream that originates in Missouri and flows into Kansas and Oklahoma. The Spring River has a fish community that includes the Neosho madtom Noturus placidus, a species federally listed as threatened. Although anthropogenic factors such as contaminants limited populations and densities of fishes, an integrated assessment of natural and anthropogenic factors was necessary to effectively estimate the influence of the latter. Fish populations in the …
Restoring Ecological Integrity Of Great Rivers: Historical Hydrographs Aid In Defining Reference Conditions For The Missouri River, David L. Galat, Robin Lipkin
Restoring Ecological Integrity Of Great Rivers: Historical Hydrographs Aid In Defining Reference Conditions For The Missouri River, David L. Galat, Robin Lipkin
United States Geological Survey: Staff Publications
Restoring the ecological integrity of regulated large rivers necessitates characterizing the natural flow regime. We applied ‘Indicators of Hydrologic Alteration’ to assess the natural range of variation of the Missouri River’s flow regime at 11 locations before (1929–1948) and after (1967–1996) mainstem impoundment. The 3768 km long Missouri River was divided into three sections: upper basin least-altered from flow regulation, including the lower Yellowstone River; middle basin inter-reservoir, and lower basin channelized. Flow regulation was associated with a reduction in magnitude and duration of the annual flood pulse, an increase in magnitude and duration of annual discharge minima, a reduction …
Nutrients In Groundwaters Of The Conterminous United States, 1992-1995, Bernard Nolan, Jeffrey Stoner
Nutrients In Groundwaters Of The Conterminous United States, 1992-1995, Bernard Nolan, Jeffrey Stoner
United States Geological Survey: Staff Publications
Results of a national water quality assessment indicate that nitrate is detected in 71% of groundwater samples, more than 13 times as often as ammonia, nitrite, organic nitrogen, and orthophosphate, based on a common detection threshold of 0.2 mg/L. Shallow groundwater (typically 5 m deep or less) beneath agricultural land has the highest median nitrate concentration (3.4 mg/L), followed by shallow groundwater beneath urban land (1.6 mg/L) and deeper groundwater in major aquifers (0.48 mg/L). Nitrate exceeds the maximum contaminant level, 10 mg/L as nitrogen, in more than 15% of groundwater samples from 4 of 33 major aquifers commonly used …
Geomorphometry – Diversity In Quantitative Surface Analysis, Richard J. Pike
Geomorphometry – Diversity In Quantitative Surface Analysis, Richard J. Pike
United States Geological Survey: Staff Publications
A widening variety of applications is diversifying geomorphometry (digital terrain modelling), the quantitative study of topography. An amalgam of earth science, mathematics, engineering and computer science, the discipline has been revolutionized by the computer manipulation of gridded terrain heights, or digital elevation models (DEMs). Its rapid expansion continues. This article reviews the remarkable diversity of recent morphometric work in 15 selected topics and discusses their significance and prospects. The quantitative analysis of industrial microsurface topography is introduced to the earth science community. The 14 other topics are Internet access to geomorphometry; global DEMs; DEM modelling of channel networks; …
Single-Dilution Enzyme-Linked Immunosorbent Assay For Quantification Of Antigen-Specific Salmonid Antibody, Stewart W. Alcorn, Ronald J. Pascho
Single-Dilution Enzyme-Linked Immunosorbent Assay For Quantification Of Antigen-Specific Salmonid Antibody, Stewart W. Alcorn, Ronald J. Pascho
United States Geological Survey: Staff Publications
An enzyme-linked immunosorbent assay (ELISA) was developed on the basis of testing a single dilution of serum to quantify the level of antibody to the p57 protein of Renibacterium salmoninarum in sockeye salmon (Oncorhynchus nerka). The levels of antibody were interpolated from a standard curve constructed by relating the optical densities (OD) produced by several dilutions of a high-titer rainbow trout (O. mykiss) antiserum to the p57 protein. The ELISA OD values produced by as many as 36 test sera on each microplate were compared with the standard curve to calculate the antigen-specific antibody activity. Repeated …
Holocene Environmental And Climatic Change In The Northern Great Plains As Recorded In The Geochemistry Of Sediments In Pickerel Lake, South Dakota, Walter E. Dean, Antje Schwalb
Holocene Environmental And Climatic Change In The Northern Great Plains As Recorded In The Geochemistry Of Sediments In Pickerel Lake, South Dakota, Walter E. Dean, Antje Schwalb
United States Geological Survey: Staff Publications
The sediments in Pickerel Lake, northeastern South Dakota, provide a continuous record of climatic and environmental change for the last 12000 yr. Sediments deposited between 12 and 6 ka (radiocarbon) show extreme variations in composition, oxygen and carbon isotopic composition of bulk carbonate, carbon isotopic composition of organic matter, and magnetic susceptibility. These variations reflect changes in sources of moisture, regional vegetation types, precipitation-evaporation balance, ground- and surface-water influx, water residence time, erosion, lake productivity, water level, and water temperature. The total carbonate content of late Pleistocene sediments steadily increased from <20% at the base of the core to as much as 80% in sediments deposited between 11 and 9 ka. By about 8 ka, the total carbonate content of the sediments had declined to about 40% where it remained with little variation for the past 8 kyr, suggesting relatively stable conditions. There are marked increases in values of δ13C and δ18O in bulk carbonate, …
Pore Fluid Pressure, Apparent Friction, And Coulomb Failure, N. M. Beeler, R. W. Simpson, S. H. Hickman, D. A. Lockner
Pore Fluid Pressure, Apparent Friction, And Coulomb Failure, N. M. Beeler, R. W. Simpson, S. H. Hickman, D. A. Lockner
United States Geological Survey: Staff Publications
Many recent studies of stress-triggered seismicity rely on a fault failure
model with a single free parameter, the apparent coefficient of friction, presumed to be a material constant with possible values 0 ≤ μ ' ≤ 1. These studies may present a misleading view of fault strength and the role of pore fluid pressure in earthquake failure. The parameter μ ' is intended to incorporate the effects of both friction and pore pressure, but is a material constant only if changes in pore fluid pressure induced by changes in stress are proportional to the normal stress change across the potential …
Analysis Of Selected Herbicide Metabolites In Surface And Ground Water Of The United States, Elisabeth A. Scribner, E. M. Thurman, Lisa R. Zimmerman
Analysis Of Selected Herbicide Metabolites In Surface And Ground Water Of The United States, Elisabeth A. Scribner, E. M. Thurman, Lisa R. Zimmerman
United States Geological Survey: Staff Publications
One of the primary goals of the US Geological Survey (USGS) Laboratory in Lawrence, Kansas, is to develop analytical methods for the analysis of herbicide metabolites in surface and ground water that are vital to the study of herbicide fate and degradation pathways in the environment. Methods to measure metabolite concentrations from three major classes of herbicides ─ triazine, chloroacetanilide and phenyl-urea ─ have been developed. Methods for triazine metabolite detection cover nine compounds: six compounds are detected by gas chromatography/mass spectrometry; one is detected by high-performance liquid chromatography with diode-array detection; and eight are detected by liquid chromatography/mass spectrometry. …
Dating Marine Terraces With Relative-Age And Correlated-Age Methods, Daniel R. Muhs
Dating Marine Terraces With Relative-Age And Correlated-Age Methods, Daniel R. Muhs
United States Geological Survey: Staff Publications
Coastal landforms, and particularly emergent marine terraces, a re amongt he most importantg eomorphicfe aturesi n studieso f Quaternarys eal evel fluctuationsa nd neotectonics. A general model, first articulated by Alexander (1953) and borne out by detailedr ecent studieso n many coastlinesi,s that emergent flights of erosional terraces and coral reefs (Fig. 1) are the resulto f glacioeustaticallyc ontrolledf luctuations of global sea level superimposed on steady uplift. Similiarity of U-series ages of coral from both constructional reefsi n the tropicsa nd erosionalt erracesi n midlatitudesh as provided a rigorous test of this model (Mesolella and others, 1969; Bloom and …
Relation Of Pathways And Transit Times Of Recharge Water To Nitrate Concentrations Using Stable Isotopes, Matthew K. Landon, Geoffrey N. Delin, Stephen C. Komor, Charles P. Regan
Relation Of Pathways And Transit Times Of Recharge Water To Nitrate Concentrations Using Stable Isotopes, Matthew K. Landon, Geoffrey N. Delin, Stephen C. Komor, Charles P. Regan
United States Geological Survey: Staff Publications
Oxygen and hydrogen stable isotope values of precipitation, irrigation water, soil water, and ground water were used with soil-moisture contents and water levels to estimate transit times and pathways of recharge water in the unsaturated zone of a sand and gravel aquifer.
Effects Of Topography And Soil Properties On Recharge At Two Sites In An Agricultural Field, Geoffrey N. Delin, Richard W. Healy, Matthew K. Landon, John Karl Böhlke
Effects Of Topography And Soil Properties On Recharge At Two Sites In An Agricultural Field, Geoffrey N. Delin, Richard W. Healy, Matthew K. Landon, John Karl Böhlke
United States Geological Survey: Staff Publications
Field experiments were conducted from 1992 to 1995 to estimate ground water recharge rates at two sites located within a 2.7-hectare agricultural field. The field lies in a sand plain setting in central Minnesota and is cropped continuously in field corn. The sites are located at a topographically high (upland) site and a topographically low (lowland) site in an effort to quantify the effects of depression focusing of recharge. Three site-specific methods were used to estimate recharge rates: well hydrograph analysis, chlorofluorocarbon age dating, and an unsaturated zone water balance. All three recharge methods indicated that recharge rates at the …
Dakota County Test Hole Logs, Raymond R. Burchett, Frank A. Smith
Dakota County Test Hole Logs, Raymond R. Burchett, Frank A. Smith
Conservation and Survey Division
No abstract provided.