An isotopic and geochemical study of snowmelt runoff in a small arctic watershed

‘Old’ water contributions to snowmelt runoff in a stream can be defined as water which was stored in the catchment prior to the start of the runoff event in question. We used mass balance techniques for natural oxygen-18 and several chemical parameters (electrical conductivity, Ca and Mg) to estimate the magnitude and timing of ‘old’ water contributions to snowmelt runoff in the Apex River watershed during the 1983 field season. The Apex River catchment is located in the southern part of Baffin Island, Northwest Territories, Canada. The watershed has an area of 60 km², it is in the zone of continuous permafrost, and the geology is dominantly Precambrian gneiss with sporadic, thin, glacial overburden. The isotopic data indicate that for the snowmelt season of 1983 (third highest peak discharge of 11 years of record), approximately 50 per cent of the peak stream discharge consisted of ‘old’ water. Our data also suggest that about 60 per cent of the entire 1983 hydrograph was ‘old’ water. The chemical parameters give old water contributions which are at least 10 per cent less than the isotopically-derived estimate, but they are consistent with the isotopic estimate during peak flow.     

Distortions of the Moon's figure due to the Earth

The second zonal and the second sectorial Stokes parameters of the Moon's gravitational field and/or the polar and equatorial flattenings of the lunar triaxial level ellipsoid have been explained by the tidal and rotational distortions due to the Earth. The Epoch at which the Moon's figure formation was finished has been estimated as 1.6 × 10⁹ y B. P. when the Earth-Moon distance was about 168 400 km and the orbital/rotational period of the Moon about 8 days.     

On the parameters of the normal earth's gravity field

Summary The parameters of the normal Earth's gravity field, determined from contemporary satellite data are discussed and compared with the parameters of the normal Helmert system (1901 to 1909).Dedicated to Academician Alois Zátopek on His 65th Birthday     

AXIOM: advanced X-ray imaging of the magnetosphere

Planetary plasma and magnetic field environments can be studied in two complementary ways—by in situ measurements, or by remote sensing. While the former provide precise information about plasma behaviour, instabilities and dynamics on local scales, the latter offers the global view necessary to understand the overall interaction of the magnetospheric plasma with the solar wind. Some parts of the Earth’s magnetosphere have been remotely sensed, but the majority remains unexplored by this type of measurements. Here we propose a novel and more elegant approach employing remote X-ray imaging techniques, which are now possible thanks to the relatively recent discovery of solar wind charge exchange X-ray emissions in the vicinity of the Earth’s magnetosphere. In this article we describe how an appropriately designed and located X-ray telescope, supported by simultaneous in situ measurements of the solar wind, can be used to image the dayside magnetosphere, magnetosheath and bow shock, with a temporal and spatial resolution sufficient to address several key outstanding questions concerning how the solar wind interacts with the Earth’s magnetosphere on a global level. Global images of the dayside magnetospheric boundaries require vantage points well outside the magnetosphere. Our studies have led us to propose ‘AXIOM: Advanced X-ray Imaging of the Magnetosphere’, a concept mission using a Vega launcher with a LISA Pathfinder-type Propulsion Module to place the spacecraft in a Lissajous orbit around the Earth–Moon L1 point. The model payload consists of an X-ray Wide Field Imager, capable of both imaging and spectroscopy, and an in situ plasma and magnetic field measurement package. This package comprises a Proton-Alpha Sensor, designed to measure the bulk properties of the solar wind, an Ion Composition Analyser, to characterise the minor ion populations in the solar wind that cause charge exchange emission, and a Magnetometer, designed to measure the strength and direction of the solar wind magnetic field. We also show simulations that demonstrate how the proposed X-ray telescope design is capable of imaging the predicted emission from the dayside magnetosphere with the sensitivity and cadence required to achieve the science goals of the mission.     

Sedimentation rate of soil microparticles

The aim of the submitted paper is to identify the lower limit of Stokes’ law for calculating the deposition rate of soil microparticles. The authors’ hypothesis on the lower limit of Stokes’ law is based on the idea that with the gradual formation of the colloidal dispersion system, both the particle size and the sedimentation rate decrease. It is assumed that under the lower particle size limit, Stokes’ law does not apply. As a result of the diffusion, the state of the sedimentation equilibrium gradually emerges. The results of the experiment showed that in laboratory conditions, Stokes’ equation ceases to be valid for sedimentation of the particles sized d(90)?<?2 μm. During the experiment, a dynamic sedimentation equilibrium was reached at the particle size d(90)?=?0.27 μm. The scientific contribution of this knowledge is the accuracy of the determination of hydropedological characteristics dependent on the texture of the soil. In this context, the results stated in the paper define the lower limit of the validity for the laboratory procedures determining soil texture on the basis of the sedimentation methods. To identify the textures below this limit, it is necessary to choose the methods based on other principles. Determination of the lower limit is particularly important in clay soils containing a high proportion of clay particles (clay particles <?2 μm).     

Carbon Sequestration and Sediment Accretion in San Francisco Bay Tidal Wetlands

Tidal wetlands play an important role with respect to climate change because of both their sensitivity to sea-level rise and their ability to sequester carbon dioxide from the atmosphere. Policy-based interest in carbon sequestration has increased recently, and wetland restoration projects have potential for carbon credits through soil carbon sequestration. We measured sediment accretion, mineral and organic matter accumulation, and carbon sequestration rates using ¹³⁷Cs and ²¹⁰Pb downcore distributions at six natural tidal wetlands in the San Francisco Bay Estuary. The accretion rates were, in general, 0.2?C0.5?cm?year^?1, indicating that local wetlands are keeping pace with recent rates of sea-level rise. Mineral accumulation rates were higher in salt marshes and at low-marsh stations within individual sites. The average carbon sequestration rate based on ²¹⁰Pb dating was 79?g?C?m^?2?year^?1, with slightly higher rates based on ¹³⁷Cs dating. There was little difference in the sequestration rates among sites or across stations within sites, indicating that a single carbon sequestration rate could be used for crediting tidal wetland restoration projects within the Estuary.     

Combined inelastic neutron scattering and solid-state DFT study of dynamics of hydrogen atoms in trioctahedral 1M phlogopite

Inelastic neutron scattering (INS) was used to study the vibrational dynamics of the hydrogen atoms in natural trioctahedral phlogopite, K_0.93Na_0.03(Mg_2.47Fe_0.22Al_0.16Fe_0.04Tl_0.06)[Si_2.84Al_1.16]O₁₀OH_1.71F_0.28Cl_0.01, within the 50–1,000?cm^?1 energy range. The INS spectra collected using direct geometry spectrometer SEQUOIA (ORNL) were interpreted by means of the solid-state DFT calculations covering both normal mode analysis and molecular dynamics. To optimize the structure and to calculate the vibrational modes under harmonic approximation, both a hybrid PBE0 and the AM05 functional were used, while the molecular dynamics calculations (60?ps/1?fs) were performed only with the computationally less-demanding AM05 functional. The main contributions to the dominant band within ~750–550?cm^?1 are symmetric and antisymmetric Mg–O–H bending modes, overlapping with the skeletal stretching and bending modes causing weaker secondary movements of H atoms of inner hydroxyl groups. Signatures of the Mg–O–H bending modes appear down to ~400?cm^?1, where a region of octahedra deformation modes starts. These deformations cause just shallow movements of the hydrogen atoms and are mirrored by the modes with close vibrational energies. The region from ~330?cm^?1 down to the low-energy end of the spectrum portrays induced vibrations of the H atoms caused by deformation of individual polyhedra, translational vibrations of the parts of the 2:1 layer relative one to another, and librational and translational vibrations of the layer. The main difference between the INS spectrum of dioctahedral Al-muscovite and trioctahedral Mg-phlogopite is that the Mg–O–H modes are all assigned to in-plane vibrations of the respective hydrogen atoms.     

A new approach in assessing recharge of highly karstified terrains–Montenegro case studies

The recharge of a karst aquifer, in terms of its quantity and spatial distribution, depends on various natural factors such as climate, topography, vegetation, soil, and geology. Selection of an adequate method for assessing recharge in karst is often a matter of dispute. Multi-parameter methods using Geographical information systems tools have recently been successfully developed and applied in karstic terrains of Spain and Lebanon. Specific local conditions such as highly karstified terrains could additionally complicate such an assessment. The Montenegro karstified terrains in the southern part of the External Dinarides are characterized by a very high precipitation rate, irregular seasonal distribution, and absence of surface waters (extremely high infiltration capacity of karst). Considering such conditions, an attempt to apply existing knowledge and experiences to the development of an appropriate multi-parameter method for assessing spatial distribution of autogenous recharge has been made. The KARSTLOP method has been developed, applied, and calibrated at catchments of several large karst springs of Montenegro. Obtained results in tested catchment areas confirm that with some further improvements the KARSTLOP method could be a useful tool to support research of karstic aquifers in similar highly karstified terrains.     

Strong earthquakes associated with high amplitude daily geomagnetic variations

In this work, we attempt to quantify forces that result from the interaction between the induced Sq-variation currents in the Earth’s lithosphere and the regional Earth’s magnetic field, in order to assess its influence on the tectonic stress field and on seismic activity. The study area is the Sinai Peninsula, a seismically active region where both seismic and magnetic data are available. We show that both short-term and long-term magnetic changes correlate with the seismic activity extending to this area in other previous studies. We also analyze a set of large earthquakes and magnetic data from observatories around the world to deduce a relationship between earthquake magnitude and maximum distance up to which precursory variations of the magnetic field are observed.     

Letter to the editor A comparison of F-region ion velocity observations from the EISCAT Svalbard and VHF radars with irregularity drift velocity measurements from the CUTLASS Finland HF radar

During August 1998, the UK EISCAT special programme SP-UK-CSUB, which combines operation of both the mainland VHF and Svalbard UHF incoherent scatter radars, was run for several hours around magnetic midnight on four consecutive days. The CUTLASS Finland HF coherent scatter radar was, at these times, operating in a discretionary mode, sounding on all 16 beams, one at high-time resolution. This study presents a comparison of the velocities measured by coherent and incoherent techniques during the SP-UK-CSUB experiments. Agreement, particularly between the ion velocities measured by the EISCAT Svalbard radar and irregularity drift measurements by the Finland radar, is remarkable, thereby validating the scientific integrity of both data sets. This work highlights the substantive contribution to our understanding of the solar-terrestrial environment which can be made by use in concert of incoherent and HF coherent scatter radars.