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At least 811 records · Page 45Linked to original sources

USGS1977

Simulation of flow from an aquifer to a partially penetrating trench

Construction of the Tennessee-Tombigbee Waterway in northeast Mississippi will involve dewatering as much as 46 m of an unconfined aquifer near the Tennessee Valley divide. Dewatering by trenching is one of the proposed methods. Methods of calculating effects of dewatering by trenching have been heretofore limited to situations where ideal conditions such as isotropic aquifers and fully penetrating trenches occur. In order to study the effects of trenching on the water table in the more complicated hydrologic system in northeast Mississippi, a two-dimensional cross-sectional digital model was developed from an existing two-dimensional digital model. To make the solutions obtained from the model applicable to any aquifer thickness or other hydrologic condition, a technique for nondimensional simulation was developed. With these techniques, nondimensional water-surface profiles were generated for given stages of trench penetration of the aquifer and for different ratios of anisotropy.

Mississippi↗

USGS1977

A method for adjusting values of Manning's roughness coefficient for flooded urban areas

A method is presented for adjusting values of Manning's roughness coefficient for flooded urban areas on the basis of the density of buildings on a flood plain and verified roughness coefficients for natural conditions. An urban roughness coefficient can be calculated to emulate the water-surface profiles to within 0.06 meter for depths of flow less than 0.6 meter and plus or minus 10 percent for depths between 0.6 and 2 meters.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Periphyton and phytoplankton in the Sacramento River, California, May 1972 to April 1973

Periphyton and phytoplankton samples were collected monthly at five sites in the Sacramento River between May 1972 and April 1973. Periphyton were analyzed for species identification and biomass, and phytoplankton were analyzed for species identification and concentrations. The results were used to assess biological water-quality conditions in the river and to compare phytoplankton types and concentrations at three sites with those in 1960-61. Diatoms were the dominant group in both numbers and types of periphyton and phytoplankton. The number of genera and frequency of occurrence of periphyton increased downstream. The periphyton biomass decreased downstream and with succeeding monthly sampling periods. The highest productivity was at site B, below Red Bluff, probably because the Red Bluff Diversion Dam provides optimum conditions for periphyton growth. The decreasing productivity downstream is probably a function of higher sediment concentrations. The periphyton biomass ranged from 0.00 to 0.56 grams per square meter per day throughout the study period. Phytoplankton concentrations and diversity increased downstream. The highest phytoplankton concentration was 980 organisms per milliliter at site D, above Knights Landing, in September. The diversity indices ranged from 0.95 to 3.88 for all sites throughout the study period. Fewer phytoplankton genera were collected in 1972-73 than in 1960-61, but the generic composition was similar. Total phytoplankton concentrations were nearly always higher in 1960-61 than in 1972-73. Green algal concentrations were significantly higher ( p <0.05) at site C and diatoms were significantly higher at all three sites in 1960-61. Blue-green algal concentrations were higher in 1972-73, but differences between the two time intervals were not significant.

California↗

USGS1977

Feasibility and technology for making remote measurements of solutes in water

An indepth evaluation of the available technology in the field of laser-Raman spectroscopy indicates that a TV-type detector, a single monochromator with a holographic grating, an entrance slit filter blocking the Rayleigh light, and a pulsed laser coupled to signal averaging electronics is the best combination of commercial equipment that is presently available for building a remote water-quality sensor. The resultant sensor would be capable of measuring oxyanions in water at concentrations from 10 to 50 milligrams per liter at distances from ground level to 30 meters above the sample. The main interferences would be ambient light, bioluminescence, and natural fluorescence, all of which are minimized when taking advantage of the signal generating and readout capability contained in this equipment package.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Chemical structure of humic acids - Part 1, a generalized structural model

A new model is proposed for the structure of humic acids. In this model humic acid is pictured as being made up of a hierarchy of structural elements. At the lowest level in this hierarchy are simple phenolic, quinoid, and benzene carboxylic acid groups. These groups are bonded covalently into small particles. Particles of similar chemical structure are linked together by weak bonds to form "homogeneous" aggregates. Two or more different types of aggregates may be linked together to form mixed aggregates. Complexes of humic acid and clay minerals are also formed.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Chemical structure of humic acids - Part 2, the molecular aggregation of some humic acid fractions in N, N-dimethylformamide

Humic acid fractions form molecular aggregates in solution. In previous studies we have shown by small angle X-ray scattering that the size of these aggregates is a function of pH. In this study we have found that the size of the aggregates of two humic acid fractions in water and buffers and in dimethylformamide solutions can be changed by oxidation with molecular oxygen and air. These results cast new light on the bonding mechanisms that cause aggregation of the humic acid particles in solution. We have interpreted the changes in aggregation sizes as being brought about by changes in intermolecular and intramolecular hydrogen bonding of the humic particles. Solvation of the humic molecules by dimethylformamide interferes with some of the hydrogen bonding reactions between proton donor and acceptor groups on the same humic acid molecules or on different molecules.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Thallium contents of 16 USGS standard rocks

Thallium was determined in 16 USGS standard rocks by atomic absorption spectroscopy in which a heated graphite atomizer was used after extraction as thallium iodide into amyl acetate. Four subsamples from four bottles of each standard sample, except G-1 and W-1, were analyzed in random order, and the average thallium contents in parts per million (as Tl) were AGV-1, 0.41; GSP-1, 1.63; G-2, 1.08; BCR-1, 0.35; SDC-1, 0.80; MAG-1, 0.79; BHVO-1, 0.049; SCO-1, 0.79; SGR-1, 0.34; QLO-1, 0.23; RGM-1, 1.07 ; STM-1, 0.30; DTS-1, <0.005; and PCC-1, <0.005. The analysis of variance showed that all samples may be considered homogeneous at F 0.975 and only GSP-1 may be considered heterogeneous at F 0.95 . The Tl contents of G-1 and W-1 are 1.0 and 0.12 ppm, respectively.

Journal of Research of the U.S. Geological Survey↗

USGS1977

An improved ion-selective electrode method for the rapid determination of fluorine in rocks and soil

An improved method based on an ion-selective electrode technique for the analysis of fluorine in rocks and soils is presented. Analyses are made by using a sodium carbonate-potassium carbonate fusion and a citric acid dissolution of the fuseate. Prior to determining the fluorine concentration by a standard-addition procedure, sodium citrate buffer is added to the solution. The proposed method yields fluorine values in agreement with known values for standard rocks. Values of this method are also presented for six geochemical exploration rock-and-soil reference samples and compared to those from other ion-selective electrode techniques. Fifty samples can be analyzed in 1 person-day. The sensitivity of the method is 100 parts per million, and samples containing up to 45 percent fluorine have been successfully analyzed.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Preparation of pyrite-coated sand grains for research on roll-type uranium deposits

Ordinary quartz sand grains can be coated with pyrite for use in laboratory experiments on the genetic geochemistry of roll-type uranium deposits. The sand is first added to a ferric chloride solution. The slow addition of sodium hydroxide to the mixture gives the sand grains an iron oxide coating. This coating is then converted to pyrite by reaction with hydrogen sulfide, thus yielding a product suitable for experimental use.

Journal of Research of the U.S. Geological Survey↗

USGS1977

A thermostatic water bath for experimental studies in aqueous solutions

A temperature-controlled water bath for the study of ion-pairing equilibria and mineral solubility in aqueous solutions below 100°C is described. The bath is similar to a previously described system (P. B. Hostetler and C. L. Christ, 1968, U.S. Geol. Survey Prof. Paper 600-D, p. D217-D221) but incorporates several significant improvements. Included among these are a more efficient stirring mechanism, a potentially larger solid-to-solution ratio, and improved equilibration of the gas phase with the solution.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Pressure corrections for fluid-inclusion homogenization temperatures based on the volumetric properties of the system NaCl-H 2 O

A series of pressure correction diagrams for 1-, 5-, 10-, 15-, 20-, and 25-percent NaCl solutions has been generated from the volumetric data for NaCl by R. W. Potter II and D. L. Brown in 1975. The diagrams cover the temperature range from 20° to 400° C at pressures up to 200 megapascals (2000 bars). These data can be used to correct fluid-inclusion homogenization temperatures for pressures greater than the liquid-vapor pressure-temperature curve.

Journal of Research of the U.S. Geological Survey↗

USGS1977

Exploration geochemical studies of some sandstone copper-uranium deposits, Bradford, Columbia, and Lycoming Counties, Pa

Semi-quantitative spectrographic analyses of mineralized and unmineralized sandstone, siltstone, and claystone from the Catskill Formation of Devonian age in Bradford, Columbia, and Lycoming Counties, Pa., suggest that copper, silver, and uranium are the principal metallic elements concentrated in the mineralized rock. Lead, mercury, and molybdenum may be concentrated slightly in mineralized rock but values are too low to be of use in exploration. The deposits are too small to make large anomalies in stream sediments except in drainage basins of less than a few acres. However, if a large deposit were exposed to weathering, it would probably be detectable by stream sediment sampling. Analyses of oxalic acid leachates of the minus 80-mesh fraction of the stream-sediment samples gave more useful values than analyses of the minus 80-mesh samples in separating drainage basins that have copper deposits from those that have no known copper deposits.

Pennsylvania↗

USGS1977

Rare earths, thorium, and other minor elements in sphene from some plutonic rocks in west-central Alaska

Sphene is an abundant accessory mineral in some abnormally radioactive plutonic rocks in west-central Alaska. Seven samples of sphene from four different areas in west-central Alaska contained from 20350 to 39180 parts per million total rare earths and 390 to 2000 ppm thorium. The lanthanide content in six of the seven sphenes is chiefly the light rare earths and is similar to that of crustal abundance; a seventh sphene from the Darby Mountains, however, contains above average amounts of the heavy rare earths. A comparison of the lanthanide distribution in sphene from several areas indicates that the structure of sphene will accommodate whatever lanthanides are available when the mineral crystallizes. The amount of thorium and rare earths in sphene is also affected by the presence of other accessory minerals. Sphene in rocks containing either allanite or zircon has a lower thorium content than in rocks that do not contain allanite or zircon. Sphene, because of its abundance, may contain the greater part of the rare earths and thorium in some of the plutonic rocks of west-central Alaska.

Alaska↗

USGS1977

Occurrence of bloedite and related minerals in marine shale of Diablo and Temblor Ranges, California

Bloedite, epsomite, and related minerals occur in small amounts throughout the arid eastern foothills of the Diablo and Temblor Ranges, as efflorescences on siliceous shale and as deposits around small springs and a brine pond. These minerals ultimately are products of weathering of underlying organic shale, and they are reminders that the chemistry of weathering of reduced organic shale is largely a reversal of the chemistry of its early diagenesis.

California↗

USGS1977

Comparison of granitic intrusions in the Pelona and Orocopia Schists, southern California

Dating of some small plutons in the San Gabriel and Chocolate Mountains, southern California, yields Miocene K-Ar ages. A single granodiorite pluton that has been segmented by branches of the San Jacinto fault intrudes the Pelona Schist and yields ages of 14.0 to 18.6 million years. Several quartz monzonite plutons in the Chocolate Mountains, 235 kilometers to the southeast and on the opposite side of the San Andreas fault, yield ages ranging from 20.0 to 23.4 m.y. At least one pluton in the Chocolate Mountains intrudes the Orocopia Schist, a probable equivalent of the Pelona Schist. Chemical, modal, textural, mineralogical, and apparent K-Ar age differences suggest that the two groups of plutons are not offset parts of a single body, but the differences do not preclude the two groups from being related in a general way.

California↗

USGS1975

Information through color imagery

The color-sensing capability of the human eye is a powerful tool. In remote sensing we should use color to display data more meaningfully, not to re-create the scene. Color disappears with distance, and features change color with viewing angle. Color infrared film lets us apply color with additional meaning even though we introduce a false color response. Although the marginal gray scale on an ERTS (Earth Resources Technology Satellite) image may indicate balance between the green, red, and infrared bands, and although each band may be printed in a primary color, tests show that we are not fully applying the three primary colors. Therefore, contrast in the green band should be raised. For true three-color remote sensing of the Earth, we must find two generally meaningful signatures in the visible spectrum, or perhaps extend our spectral range. Before turning to costly digital processing we should explore analog processing. Most ERTS users deal with relative spectral radiance; the few concerned with absolute radiance could use the computer-compatible tapes or special annotations. NASA (National Aeronautics and Space Administration), which assigns the range and contrast to the ERTS image, controls processing and could adjust the density range for maximum contrast in any ERTS scene. NASA cannot alter processing for local changes in reflective characteristics of the Earth but could adjust for Sun elevation and optimize the contrast in a given band.

Journal of Research of the U.S. Geological Survey↗

USGS1975

Estimates of temperature and precipitation for northeastern Utah

Estimates of temperature and precipitation were made for northeastern Utah from information that was collected at 67 locations. The variable-length records were converted to the common-time base of 1941-70; then general relations were developed to extend the converted point values to unsampled sites. Regression techniques were used to fill voids in the temperature-data base. Incomplete precipitation records were adjusted to the 1941-70 average on the assumption that the ratio of concurrent data is directly proportional to the ratio of the respective 1941-70 average annual values at nearby sites. Equations were then developed through a computer program to express the relationship of temperature and precipitation with altitude and location and to extend the information to unsampled sites. Two-thirds of the observed and estimated average annual temperature and precipitation values are within ±1.5°F (1.0°C) and 2.08 in (53 mm), respectively, of the calculated averages. Schematic diagrams, plotted by computer, were prepared to show variations of altitude, temperature, and precipitation; and maps, also plotted by computer, show lines of equal altitude, precipitation, and temperature.

Utah↗

USGS1975

Delineation of buried glacial drift aquifers

Locating and delineating buried glacial-drift aquifers poses one of the major problems to hydrogeologists working in glacial terrain. To show the vertical and horizontal boundaries of aquifers, most techniques require a multiple set of maps, a fence diagram, or a combination of maps and sections. Calculations of the first two moments, mean and standard deviation, of a discontinuous distribution result in values that represent the center of gravity (mean position) and spread (standard deviation) of all the sand units in a drill hole. Data for the moment method consist of depth to center point and thickness of each sand unit. A 2.600 mi 2 (6,730 km 2 ) area in northwestern Minnesota that, contained 71 test holes drilled to bedrock was used to test the usefulness of the moment method in glacial terrain. Plots of relative position of center of gravity and relative spread (calculated as percentage of total drift thickness) showed three groupings for relative center of gravity (shallow, 0-26 percent, medium, 30-55. and deep 58-72) and three for spread of sand units (narrow, 1-5 percent, medium, 8-19, and wide, 22-38). The resulting vertical-variability pattern map shows the areas of each of the nine combinations of these two factors. Because the vertical-variability map does not show quantity of sand, the map is most informative if the total thickness of sand, 01- percent sand of total drift thickness, is recorded by each hole location on the map. The center of gravity is useful for describing the vertical position of the principal sand in a drill hole because it lies within the principal sand unit in 34 of the 63 holes that contained sand, and it is within 15 percent (based on total drift, thickness) of the principal sand unit in 22 of the remaining 29 holes.

Michigan, Minnesota↗