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At least 1,369 records · Page 76Linked to original sources
USGS2010

Modeling biotic uptake by periphyton and transient hyporrheic storage of nitrate in a natural stream

To a convection-dispersion hydrologic transport model we coupled a transient storage submodel (Bencala, 1984) and a biotic uptake submodel based on Michaelis-Menten kinetics (Kim et al., 1990). Our purpose was threefold: (1) to simulate nitrate retention in response to change in load in a third-order stream, (2) to differentiate biotic versus hydrologie factors in nitrate retention, and (3) to produce a research tool whose properties are consistent with laboratory and field observations. Hydrodynamic parameters were fitted from chloride concentration during a 20-day chloride-nitrate coinjection (Bencala, 1984), and biotic uptake kinetics were based on flume studies by Kim et al. (1990) and Triska et al. (1983). Nitrate concentration from the 20-day coinjection experiment served as a base for model validation. The complete transport retention model reasonably predicted the observed nitrate concentration. However, simulations which lacked either the transient storage submodel or the biotic uptake submodel poorly predicted the observed nitrate concentration. Model simulations indicated that transient storage in channel and hyporrheic interstices dominated nitrate retention within the first 24 hours, whereas biotic uptake dominated thereafter. A sawtooth function for V max ranging from 0.10 to 0.17 μg NO 3 -N s −1 gAFDM −1 (grams ash free dry mass) slightly underpredicted nitrate retention in simulations of 2–7 days. This result was reasonable since uptake by other nitrate-demanding processes were not included. The model demonstrated how ecosystem retention is an interaction between physical and biotic processes and supports the validity of coupling separate hydrodynamic and reactive submodels to established solute transport models in biological studies of fluvial ecosystems.

California↗
USGS2011

The periodic structure of the natural record, and nonlinear dynamics

Concepts of cyclicity in geology have involved many famous protagonists in the history of Earth sciences. Early in this century, sophisticated theories of terrestrial rhythms had been formulated by such pioneers as T. C. Chamberlin [1909], R. T. , Chamberlin [1914], Barrell [1917], Stille [1924], Joly [1925, 1930], Holmes [1926], Lull [1929], Schuchert [1932], Grabau [1940], and Umbgrove [1939 a,b, 1947] (see the review by Williams [1981]). The physical chemist S. Arrhenius [1908] had also formulated a general hypothesis for cosmological origins of terrestrial phenomena. Khain [1964] later proposed resonances between terrestrial and cosmological rhythms, and McCrea [1975] and Williams [1975] summarized evidence of galactic correlations with glaciation.

Eos, Transactions, American Geophysical Union↗
USGS2012

The nature of the pressure-induced metallization of FeO and its implications to the core-mantle boundary

The pressure and temperature-induced metallization of FeO discovered by Knittle et al [1986] is here argued to result from a Mott transition associated with increased Fe(3d)-Fe(3d) orbital overlap at high pressures. The metallic bonding in the Fe(3d) t 2g band may account for the 4% volume decrease of FeO associated with the metallization transition. If so, a structural change (B1→B2 or B1→B8) or spin-pairing transition may not need to be invoked to explain the high pressure phase transition in FeO. Below the Neel temperature of FeO, antiferromagnetic ordering of Fe spins forces the Fe (t 2g ) electrons to be localized. Since the Neel temperature increases with pressure, no metallization transition of FeO was observed by Yagi et al. [1985] in their high-pressure measurements at 300K. Neither (Mg, Fe)O and (Mg,Fe)SiO 3 can undergo a Mott transition at high pressure and temperature. Consequently, it is here argued that a lower mantle containing only these phases should be electrically insulating. Finally, the formation of itinerant d-electrons in FeO may be a necessary, if not sufficient, condition for the apparent alloying of FeO with Fe. Such alloying may allow oxygen to be incorporated into the outer core.

Geophysical Research Letters↗
USGS2012

On the nature and rate of resurfacing of Venus

Crater production and obliteration are modeled for the plains of Venus, using: (1 ) the observed distribution of Venus-crossing asteroids and comets, (2) viscous relaxation of crater topography, and (3) erosion and burial by atmospheric, volcanic, and tectonic processes. Crater lifetimes are assumed to be proportional to crater depths for both classes of obliterative processes although the individual criteria vary. An average crater retention age between 0.4 to 2.0 Ga is estimated for plains under the assumption that craters are produced and not removed. The range is driven by uncertainty in identifying degraded impact as opposed to volcanic craters. On the other hand, crater retention ages greater than about 1.6 Ga are unlikely if viscous relaxation operates without loading of crater floors by burial. Our preferred model has plains subject to crater production and obliteration processes that vary over both space and time. In some areas, radar-bright crater ejecta haloes are preserved for long periods of time because volcanism, tectonism, and weathering occurs at rates « 1 km/Ga. Viscous relaxation has probably generated numerous shallow craters in these relatively quiescent regions. In other areas, volcanism and tectonism have resurfaced the terrain at rates greater than several km/Ga. The global coverage and high resolution SAR and altimetry data expected from Magellan will allow testing of this model, based on detailed crater observations (diameter, depth distributions; morphologic criteria; surface scattering properties) and their association with volcanic and tectonic features.

Geophysical Research Letters↗
USGS2012

The nature of the crust in the Yukon-Koyukuk province as inferred from the chemical and isotopic composition of five Late Cretaceous to Early Tertiary volcanic fields in western Alaska

Late Cretaceous and early Tertiary volcanic and plutonic rocks in western Alaska comprise a vast magmatic province extending from the Alaska Range north to the Arctic Circle, south to Bristol Bay, and west to the Bering Sea Shelf. The chemical and isotopic composition of five of these Late Cretaceous to early Tertiary volcanic fields in the north central part of this province were studied to determine if Paleozoic or older continental crust underlies the Yukon-Koyukuk province. Three of the fields, the Blackburn Hills, Yukon River, and Kanuti, occur within the Yukon-Koyukuk province and two, the Sischu and Nowitna, overlie bordering Precambrian and Paleozoic metamorphic terranes to the southeast. High initial 87 Sr/ 86 Sr of 0.7075–0.7079 and moderate initial 143 Nd/ 144 Nd of 0.51244–0.51247 of rhyolite, dacite, and high-silica andesite of the Sischu volcanic field indicate that the magmas have interacted with the underlying Paleozoic or older continental crust. The relatively limited variation of isotopic (initial 87 Sr/ 86 Sr = 0.7044–0.7051; initial 143 Nd/ 144 Nd = 0.51256–0.51257) and elemental compositions of andesites from the Nowitna field can be accounted for by assimilation of small amounts of Paleozoic or older continental crust during crystal fractionation of andesite parent magmas at crustal levels. The Blackburn Hills field, which consists of medium-K basalt, andesite, and rhyolite intruded by a small granitic pluton, has a large range in initial 87 Sr/ 86 Sr and initial 143 Nd/ 144 Nd that plot in the field for 60 Ma mantle, from near mid-ocean ridge basalts to near “bulk-earth” compositions (initial 87 Sr/ 86 Sr = 0.7033–0.7052; initial 143 Nd/ 144 Nd = 0.51253–0.51290). Andesites and basalts from the Blackburn Hills are divided into two group on the basis of rare earth element (REE) and isotopic composition. Isotopic variation in the more primitive group 1 is best explained by assimilation of the lower crust of the Jurassic to Early Cretaceous Koyukuk terrane by mantle-derived basalts during crystal fractionation, though part of the isotopic variation may be due to metasomatism of an oceanic island basalt type mantle source by fluids derived from subducted sediments. Group 2 andesites from the Blackburn Hills have lower heavy REE abundances and more enriched isotopic compositions. These group 2 andesites and dacites from the Kanuti field, which have ( 87 Sr/ 86 Sr) i = 0.7043–0.7048 and ( 143 Nd/ 144 Nd) i = 0.51248–0.51267, appear to have formed by partial melting of the lower crust of the Koyukuk terrane. The Yukon River field consists of basalt, andesite, dacite, and rhyolite having ( 87 Sr/ 86 Sr) i = 0.7037–0.7051 and ( 143 Nd/ 144 Nd) i = 0.51266–0.51280; its isotopic composition does not require the presence of Paleozoic or older continental crust under the volcanic field and may have formed by interaction between mantle-derived melts and the oceanic Angayucham/Tozitna or island arc Koyukuk terrane. Most of the intrusive rocks and rhyolite domes from the Blackburn Hills volcanic field have ( 87 Sr/ 86 Sr) i = 0.7038–0.7041 and dacites from the Kanuti volcanic field have ( 87 Sr/ 86 Sr) i = 0.7043–0.7048. Thus little or no old continental crust was involved in the genesis of the Late Cretaceous and early Tertiary rocks and therefore probably does not extend beneath this part of the Yukon-Koyukuk province. However, the ultimate source of the small volumes of enriched shoshonitic andesite ( 87 Sr/ 86 Sr = 0.7075, 143 Nd/ 144 Nd = 0.5125) erupted at 118 Ma in the Yukon-Koyukuk province may be continental lithosphere, which may have been thrust under this part of the Yukon-Koyukuk province during arc-continent collision in the Early Cretaceous.

Journal of Geophysical Research Solid Earth↗
USGS2012

Wave energy saturation on a natural beach of variable slope

Time series of flow were measured across the inner surf zone during a storm. These data were used to quantify the dependence of wave height (transformed from measured flow) and velocity on local slope and depth. Similar to previous studies, as incident waves broke and propagated into the surf zone, wave energy became saturated, and wave height was strongly dependent on depth. However, the ratio of rms wave height to local depth (γ rms ) was found not to be constant but to vary between 0.29 and 0.55; γ rms increased with local slope and was independent of deepwater wave steepness. Thus the surf zone similarity parameter (the ratio of slope to the square root of steepness) did not adequately parameterize γ rms .

Journal of Geophysical Research - Oceans↗
USGS2010

Attenuation of the Coast Range ophiolite by extensional faulting and nature of the Coast Range "thrust," California

The late Mesozoic Coast Range ophiolite and Great Valley sequence in California were juxtaposed against the Franciscan Complex during a long tectonic history that included imbricate thrust faulting, low‐angle detachment, and high‐angle reverse faulting. Many low‐angle faults previously mapped as thrusts invariably juxtapose younger over older rocks, suggesting a normal sense of offset. We infer that serpentinite melange that is present structurally beneath the Coast Range ophiolite formed above the subduction zone during convergence and was subsequently faulted and further attenuated with upper plate rocks concurrent with extension. Franciscan blueschist‐facies rock is inferred to have been transported from depth to higher structural levels concurrent with underplating and extensional unroofing in the upper plate. The present juxta‐position of the Coast Range ophiolite and Great Valley sequence with Franciscan rocks is commonly controlled by Neogene high‐angle faults. We propose that the term Coast Range thrust is no longer appropriate and that the name should be changed to Coast Range fault.

California↗
USGS2014

Report of the committee on chemistry of natural waters, 1933–34

The personnel of this Committee during the past year, practically the same as during the previous year, has been as follows: C. S. Howard, Chairman—United States Geological Survey, Washington, D.C. L. C. Case—Gypsy Oil Company, Tulsa, Oklahoma. W. D. Collins—United States Geological Survey, Washington, D.C. H. F. Flynn—United States Engineer Office, 35 South Ninth Street, Philadelphia, Pennsylvania. W. P. Kelley—University of California, Riverside, California. Alfred C. Lane—Tufts College, Tufts College, Massachusetts. Augustus Locke—477 Mills Building, San Francisco, California. R. D. Leitch—United States Bureau of Mines, Pittsburgh, Pennsylvania. H. T. Logan—United States Bureau of Standards, Washington, D.C. Thomas S. Lovering—United States Geological Survey, Washington, D.C. Thomas E. Means—111 Sutter Street, San Francisco, California. F. B. Plummer—University of Texas, Austin, Texas. J. W. Sale—United States Food and Drug Administration, Washington, D.C. C S. Scofield—Bureau of Plant Industry, Department of Agriculture, Washington, D.C. Thomas G. Thompson—University of Washington, Seattle, Washington.

Eos, Transactions, American Geophysical Union↗
USGS2014

Report of the committee on chemistry of natural waters, 1935–36

The membership of this Committee was not changed during the past year. A publication has appeared during the year giving the analytical data assembled for and used as a basis for Bulletin 40 of the Department of Public Works, California. This new publication, printed as 40‐A, is entitled “Detailed analyses showing qualities of irrigation‐waters.” Analyses are given for both surface‐ and ground‐waters.

Eos, Transactions, American Geophysical Union↗
USGS2014

Report of the committee on chemistry of natural waters, 1938–39

The membership of this Committee is as follows: C. S. Howard (Chairman), United States Geological Survey, Washington, D.C. I. A. Denison, National Bureau of Standards, Washington, D.C. W. P. Kelley, 119 Hilgard Hall, University of California, Berkeley, California A. C. Lane, 22 Arlington Street, Cambridge, Massachusetts C. S. Scofield, Bureau of Plant Industry, United States Department of Agriculture, Washington, D.C. D. G. Thompson, United States Geological Survey, Washington, D.C. T. G. Thompson, University of Washington, Seattle, Washington Studies on the corrosion of metals and soils have been continued at the National Bureau of Standards and a report of the recent findings was published under the title “Correlation of the electrolytic corrosion test with the active corrosiveness of soils,” by I. A. Denison and R. B. Darnielle [J. Res., Nation. Bur. Stan., No. 21, pp. 819‐830, December, 1938], Another paper on this subject by Kirk H. Logan was published under the title “Engineering significance of National Bureau of Standards soil corrosion data” [J. Res. Nation. Bur. Stan., pp. 109–125, January. 1939].

Eos, Transactions, American Geophysical Union↗
USGS2014

Committee on chemistry of natural waters, 1939–40

The membership of this Committee is as follows: I. A. Dennison, National Bureau of Standards, Washington, D.C.; C. S. Scofield, Bureau of Plant Industry, Department of Agriculture, Washington, D.C.; D. G. Thompson, United States Geological Survey, Washington, D.C.; Prof. T. G. Thompson, University of Washington, Seattle, Washington; and C. S. Howard (Chairman), United States Geological Survey, Washington, D.C. The Committee arranged for the presentation of the following five papers at the 1940 Spring meeting: (1) Salt‐water intrusion in the Connecticut River, by C. S. Howard, United States Geological Survey; (2) Salinity‐movement and its causes in the Delaware River Estuary, by William D. Mason and Wallace R. Pietsch, Sun Oil Company; (3) Salinity of, lower Savannah River in relation to tidal action and stream‐flow, by William L. Lamar, United States Geological Survey; (4) Corrosion of ferrous and nonferrous metals and the behavior of metallic coatings in tidal marsh, by I. A. Dennison, National Bureau of Standards; (5) The contamination of underground waters by salt water near Parlin, New Jersey, by H. C. Barksdale, United States Geological Survey.

Eos, Transactions, American Geophysical Union↗
USGS2014

Report of committee on the chemistry of natural waters, 1840–41

The membership of the Committee during the past year was as follows: I. A. Dennison. Bureau of Standards; C. S. Scofield, Department of Agriculture; D. G. Thompson, Geological Survey; T. G. Thompson, University of Washington, Seattle, Washington; and C. S. Howard, United States Geological Survey, Washington, D.C. (Chairman).

Eos, Transactions, American Geophysical Union↗
USGS2014

Report of committee on the chemistry of natural waters, 1941–42

The membership of the Committee during the past year was as follows: I. A. Dennison, National Bureau of Standards; C S. Howard (Chairman), Geological Survey; C. S. Scofield, Department of Agriculture; D. G. Thompson, Geological Survey; and T. G. Thompson, University of Washington, Seattle, Washington. SCOFIELD has continued his studies in connection with the salt balance in irrigated areas and has made progress‐reports to interested parties concerning the salt balance on the El Paso Project, Wapato Project, and the Yuma Project. These studies are of great interest to those responsible for the operation of the projects and should be of considerable value to other projects in indicating the volumes of water that may be necessary under certain conditions to insure proper drainage of the project.

Eos, Transactions, American Geophysical Union↗
USGS2014

Monthly evapo‐transpiration losses from natural drainage‐basin

With limited restrictions the hydrologic cycle in a given area may be expressed essentially as follows: P = (R + E + ΔFm) in which P represents the precipitation during a given period, R that portion which has reached or will reach the stream‐channel either through surface or subsurface paths, E that part which is evaporated from land and water surfaces and transpired by vegetation during the same period, and ΔFm the change in field‐moisture content during the period. In general both E and Fm are unknown. When the period of time considered in the above expression is long, ΔFm may be neglected and then the evapo‐transpiration losses equal the difference between P (rainfall) and R (runoff) [see 1 of “References” at end of paper]; on the other hand, when the period of time considered is short and considerable rain has fallen then E may be neglected and ΔFm equals the difference between P and R represents water stored as an increment to field‐moisture to be disposed of by evapo‐transpiration during subsequent rainless periods [2].

Eos, Transactions, American Geophysical Union↗
USGS2014

Effect of water temperature on flow of a natural stream

Approximately three per cent of the variation in streamflow of the Kootenai River near Copeland, Idaho, has been found to be associated with variation in water temperature. This has been determined by correlation analysis of residuals in streamflow that were not accounted for by either gage height or slope.

Eos, Transactions, American Geophysical Union↗
USGS2010

Worth of data and natural disaster insurance

The Federal Government in the past has provided medical and economic aid to victims of earthquakes and floods. However, regulating the use of hazard-prone areas would probably be more efficient. One way to implement such land use regulation is through the national flood and earthquake insurance program. Because insurance firms base their premium rates on available information, the benefits from additional data used to improve parameter estimates of the probability distribution (governing actual disaster events) can be computed by computing changes in the premiums as a function of additional data. An insurance firm is assumed to set rates so as to trade off penalties of overestimation and underestimation of expected damages. A Bayesian preposterior analysis is applied to determine the worth of additional data, as measured by changes in consumers’ surplus, by examining the effects of changes in premiums as a function of a longer hydrologic record.

Water Resources Research↗
USGS2010

Kinetic analysis of strontium and potassium sorption onto sands and gravels in a natural channel

A kinetic, first-order mass transfer model was used to describe the sorption of strontium onto sand- and gravel-sized streambed sediments. Rate parameters, empirically determined for strontium, allowed for the prediction of potassium sorption with moderate success. The model parameters varied significantly with particle size. The sorption data were collected during an experimental injection of several elements into a small mountain pool-and-riffle stream. The sorption process onto sand- and gravel-sized sediment was relatively slow compared to changes in the dissolved concentrations.

Water Resources Research↗