River flooding, storm resuspension, and event stratigraphy on the northern California shelf: observations compared with simulations

Coast-hugging surface flood plumes occur on the inner shelf of northern California during the winter season, generating dense, near-bottom suspensions which may attain fluid mud concentrations as particles settle. The period of storm-heightened waves may continue into the flood period, leading to gravity-driven seaward displacement of the bottom suspension; or the wave regime may ameliorate, leaving the suspension to consolidate as a short-lived, inner-shelf flood bed. Such beds tend to be resuspended within days or weeks by subsequent storm events that may recreate the original high concentrations. The sediment is thus dispersed seaward by gravity flows, to be deposited as a muddy flood bed on the central shelf. The locus of deposition of these “high-concentration regimes” is a function of the relative intensities of river discharge and storm wave height. Greater discharge piles thicker storm beds nearer shore, while intense wave regimes allow deposition of the fluid mud further seaward. During events with high values of both parameters, large amount of fluid mud may bypass over the shelf edge. In contrast, “low-concentration regimes” occur during storm periods when there has been no recent flood deposition on the inner shelf. The shelf floor is better consolidated than in the previous case, and the resulting suspended sediment concentrations are lower. As a consequence, low-concentration regimes are winnowing and bypassing regimes, and the beds deposited are thinner and sandier. Algorithms describing deposition by high and low-concentration regimes have been embedded in a probabilistic model. A simulation of a 400-year sequence of beds deposited by winter storms and floods suggests that on the Eel shelf, the Holocene transgressive systems tract consists of back-stepping, seaward-fining event beds, whose timelines (bedding planes) dip more gently than do their gradational facies boundaries. At these longer time scales, flood beds dominate over storm beds.     

A comparative study of the effect of desferrioxamine B, oxalic acid, and Na-alginate on the desorption of U(VI) from goethite at pH 6 and 25 °C

Organic ligands affect the sorption and mobility of radionuclides in soils. Batch desorption experiments on goethite particles reveal the extent of uranyl desorption and hence bioavailability with different organic acids. The desorptive strength increases in the following order: background electrolyte < Na-alginate < desferrioxamine B (DFO-B) < oxalate. The sequence is consistent with decreasing molecular size and mass from alginate via DFO-B to oxalate. The concomitant Fe release in the desorption experiments indicates that desorption from goethite and not dissolution of goethite governs the mobility of adsorbed U(VI). A compilation of DFO-B surface excesses on goethite from our experiments together with literature values indicate that DFO-B adsorbs at a constant ∼3% to the goethite surface. It is surprising that such a small fraction suffices to account for the considerable uranyl desorption and thus remobilization of a radionuclide into solution. Oxalate displays higher surface concentrations but still lower than the determined uranyl surface excess. It follows that based on the high U(VI) stability constants, both organic ligands induce the desorption of uranyl species by increasing the chemical affinity of the aqueous phase. In the case of alginate, desorption of uranyl is weak and adsorbed alginate hampers any considerable detachment of U(VI) in the presence of the more potent ligands, DFO-B and oxalate. This inhibition is based on biosorption and in this respect polysaccharides in soils may retard and even halt the advance of actinides through the soil column. This hypothesis calls for further studies into the interaction of siderophores and polysaccharides with soil adsorbents and their role in the mobilization of contaminant metals.     

A new approach to the Late Miocene-Early Pliocene forms of the genus Apocricetus. Apocricetus alberti (Rodentia,Mammalia) from Venta del Moro (Cabriel Basin,Spain)

The species of the genus Apocricetus are considered to form the phyletic lineage A. aff. plinii (MN11)–A. plinii–A. alberti–A. barrierei–A. angustidens (MN16). Along this lineage, gradual morphological and biometrical changes occur, but not all the species are represented by rich populations. The assemblage of Apocricetus alberti from Venta del Moro is by far the most abundant collection of this species. This population shows a great morphological variability in some characters like the morphology of the anteroconid and the anterolophulids in m1 and the shape of the anterolophule in M1, with morphotypes that resemble both older and younger populations of Apocricetus. Along the phyletic lineage of Apocricetus, a change in the shape of m3 occurs, from predominantly subtriangular forms in the oldest populations to predominantly subrectangular in the youngest. To quantify this feature we use the posterior width of the molar and the anterior width/posterior width ratio, proposing five morphological categories, from extremely triangular to subrectangular.     

Alpine climate during the Holocene: a comparison between records of glaciers,lake sediments and solar activity

The European Alps are very sensitive and vulnerable to climate change. Recent improvements in Alpine glacier length records and climate reconstructions from annually laminated sediments of Alpine Lake Silvaplana give the opportunity to investigate the relationship between these two data sets of Alpine climate. Two different time frames are considered: the last 500–1000 years as well as the last 7400 years. First, we found good agreement between the two different climate archives during the past millennium: mass accumulation rates and biogenic silica concentration are largely in phase with the glacier length changes of Mer de Glace and Unterer Grindelwaldgletscher, and with the records of glacier length of Grosser Aletschgletscher and Gornergletscher. Secondly, the records are compared with temporally highly resolved data of solar activity. The Sun has had a major impact on the Alpine climate variations in the long term, i.e. several centuries to millennia. Solar activity varies with the Hallstatt periodicity of about 2000 years. Hallstatt minima are identified around 500, 2500 and 5000 a. Around these times grand solar minima (such as the Maunder Minimum) occurred in clusters coinciding with colder Alpine climate expressed by glacier advances. During the Hallstatt maxima around 0, 2000 and 4500 a, the Alpine glaciers generally retreated, indicating a warmer climate. This is supported by archaeological findings at Schnidejoch, a transalpine pass in Switzerland that was only accessible when glaciers had retreated. On shorter timescales, however, the influence of the Sun cannot be as easily detected in Alpine climate change, indicating that in addition to solar forcing, volcanic influence and internal climate variations have played an important role. Copyright © 2011 John Wiley & Sons, Ltd.     

A general relativistic rotating evolutionary universe

We show that when we work with coordinate cosmic time, which is not proper time, Robertson-Walker’s metric, includes a possible rotational state of the Universe. An exact formula for the angular speed and the temporal metric coefficient, is found.     

General relativistic singularity-free cosmological model

We “explain”, using a Classical approach, how the Universe was created out of “nothing”, i.e., with no input of initial energy nor mass. The inflationary phase, with exponential expansion, is accounted for, automatically, by our equation of state for the very early Universe. This is a Universe with no-initial infinite singularity of energy density.     

The 63 μm radiation field in the earth's thermosphere and its influence on the atomic hydrogen temperature

The thermal escape of hydrogen from the Earth's atmosphere is strongly affected by its temperature at the exobase. It has been suggested recently that the hydrogen temperature might be significantly lower than the thermospheric temperature as a result of a collisional exchange of energy with atomic oxygen. The tendency is to cool the hydrogen since the energy of the excited ${}^3\text{P}{}_1$ level of oxygen can be lost from the atmosphere via magnetic dipole emission of the 63 μm line (${}^3\text{P}{}_2\text{?}{}^3\text{P}{}_1$). We present here a detailed calculation of the net cooling effect as a function of altitude throughout the thermosphere. The calculations have been performed for both day and night conditions and for periods of maximum and minimum solar activity conditions. It is found that its effect on ΔT/T varies from a very small value to a maximum of ～3%. We also provide the theoretical framework for describing deviations of the 63 μm emission from local thermodynamic equilibrium and show that these effects can cause the emission to be reduced by as much as 40% near 500 km.     

General Relativistic Machian Universe

The Machian Universe, is usually described with Newtonian Physics, We give an alternative General Relativistic picture for Mach’s Universe. As such, we show that, in the correct Machian limit, Schwarzschild’s metric is coherent with Robertson-Walker’s, on condition that there be a cosmological constant, or the Universe’s rotation—or both. It is now confirmed that the Universe is accelerating, so the former condition applies. The latter was also confirmed one more time with the recently discovered NASA space probes anomalies. From Kerr-Lense-Thirring solution, we find an inverse scale-factor dependent angular speed; we then, show that the cosmological “constant” may have Classically originated from a centrifugal acceleration field.     

Pb-isotopic compositions of volcanic rocks in the West and East Philippine island arcs: presence of the Dupal isotopic anomaly

The Philippine islands are situated between two oppositely dipping zones of seismicity. With the exception of a few areas, such as in the west central Philippines where the North Palawan continental terrane (NPCT) has collided with the archipelago, these seismic zones are well defined to depths of 200 km. Active volcanic chains overlay segments in each of these zones, suggesting that subduction is presently taking place both east and west of the islands. Lavas we have studied are thus divided between what has been termed the West Philippine arc and the East Philippine arc.West Philippine arc volcanic rocks which were extruded before the Philippine archipelago collided with the NPCT, or which are younger than the collision but crop out hundreds of kilometers from the collision zone, and all but one of the rocks from the East Philippine arc fall in the MORB field on²⁰⁷Pb/²⁰⁴Pb versus²⁰⁶Pb/²⁰⁴Pb covariation diagrams. This is surprising considering the frequency with which arc materials have²⁰⁷Pb/²⁰⁴Pb ratios higher than those of MORB, the highBa/REE and Sr/REE ratios in the lavas and the possibility of sediment subduction given the small accretionary prisms. All of these rocks have high²⁰⁸Pb/²⁰⁴Pb ratios with respect to Pacific and Atlantic Ocean MORB, but are similar to Indian Ocean MORB and IOB. Thus the Philippines consist of island arcs with the peculiar Dupal isotopic anomaly documented between 0° and 60°S in the southern hemisphere and particularly in the Indian Ocean region. This demonstrates that the Dupal isotopic anomaly is not restricted to the southern hemisphere, or to MORB and OIB.Post-collision rocks cropping out near the NPCT, in the West Philippine arc, have elevated²⁰⁸Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb ratios that could be attributed to assimilation of the newly introduced continental crust (NPCT) by mantle-derived magmas or to the addition of a sedimentary component to mantle-derived magmas.