Peculiarities of the Composition of Volatiles of Diamonds Synthesized in the Fe–S–C System: Data on Gas Chromatography–Mass Spectrometry

The first chromatography–mass spectroscopy data on volatiles in diamonds synthesized in the Fe–S–C system with 5 wt % S at 1400–1450°C and 5.0–5.5 GPa indicate the evolution of volatile composition during the diamond growth and, correspondingly, the variation in redox conditions of the reaction cell. A significant role is played by various hydrocarbons (HCs) and their derivatives, the content of which can reach 87%. Our data on possible abiogenic synthesis of HCs (components of natural gas and oil) can result in global recalculations (including climate) related to the global C cycle.     

The Dynamical Model of Chemical Oscillaiton in CaF2—HCl—H2O Solid—Liquid Reaction System

Based on the physical chemistry principle ,this paper proposes that the surface adsorption catalytic mechanism of HF is the key to dissolving the oscillation of the CaF2-HCl-H2OL solid-liquid reaction system.Meanwhile the dynamical model of this system has been established in order to study its non-linear dynamical genesis.Although this mathematics model is based on CSTR reaction apparatus,it is applicable to the foliate flow reaction apparatus,too.     

Temporal and Spatial Variability of Freshwater Plumes in a Semienclosed Estuarine–Bay System

While the physical forcing mechanisms that govern the outflows of major rivers throughout the world are well documented in the literature, comparably less research has been done to examine the mechanisms that govern the contributions of small rivers and streams to coastal ocean systems. These rivers and streams provide a direct means for the transport of anthropogenic and terrigenous materials from watersheds to coastal oceans. This study describes the temporal and spatial variability of freshwater plumes from Kaneohe Stream, Hawaii, USA, after storm events in the Kaneohe Bay watershed. Freshwater plumes were examined using a combination of fixed moorings, synoptic shipboard surveys, and lagrangian surface drifters. Data sets were collected over the course of 19 months from August 2005 to March 2007 with particular attention paid to storms during the boreal winters. Stream discharge and duration were found to exert a primary control on plume persistence in the southern Kaneohe Bay system. Time series data show a strong coherence between wind forcing and surface currents, which, in combination with data derived from shipboard and aerial surveys, indicate that the spatial variability of freshwater plumes is primarily determined by atmospheric forcing.     

Experimental modeling of native carbon formation in a C–O–H fluid system

Integrated data are presented on structure–morphology features, as well as on the material and phase composition, of a fluid-produced carbonaceous substance (CS) formed under known thermodynamic conditions of the experiment (C–O–H system, 500–800°C, and 500–1000 atm). Solid products of the synthesis were examined by means of X-ray phase and thermal analyses, scanning electron microscopy combined with microprobe analysis, transmission electron microscopy, high-resolution Raman spectroscopy, IR spectroscopy, and CHN-analysis. The characteristics of the experimental CS may be applicable in genetic modeling of natural ore-bearing fluidal carbonaceous systems.     

Phlogopite Formation in the Orthopyroxene–Garnet System in the Presence of H2O–KCl Fluid in Application to the Processes of Mantle Metasomatism

Doklady Earth Sciences - The results of experimental studies are presented for reactions in the orthopyroxene–garnet–phlogopite system in the presence of H2O–KCl fluid at...     

The Coulomb–Mohr Law and the Change in the Stress–Strain State of a Landslide Prone Mass

Doklady Earth Sciences - The stresses at the points of the ground mass are determined and distributed according to the Coulomb–Mohr law in the main stresses, under compression conditions. The...     

Melt–Fluid and Fluid–Fluid Immiscibility in a Na2SO4–SiO2–H2O System and Implications for the Formation of Rare Earth Deposits

Liquid–liquid immiscibility has crucial influences on geological processes, such as magma degassing and formation of ore deposits. Sulfate, as an important component, associates with many kinds of deposits. Two types of immiscibility, including (i) fluid–melt immiscibility between an aqueous solution and a sulfate melt, and (ii) fluid–fluid immiscibility between two aqueous fluids with different sulfate concentrations, have been identified for sulfate–water systems. In this study, we investigated the immiscibility behaviors of a sulfate- and quartz-saturated Na2SO4–SiO2–H2O system at elevated temperature, to explore the phase relationships involving both types of immiscibility. The fluid–melt immiscibility appeared first when the Na2SO4–SiO2–H2O sample was heated to ~270°C, and then fluid–fluid immiscibility emerged while the sample was further heated to ~450°C. At this stage, the coexistence of one water-saturated sulfate melt and two aqueous fluids with distinct sulfate concentrations was observed. The three immiscible phases remain stable over a wide pressure–temperature range, and the appearance temperature of the fluid–fluid immiscibility increases with the increased pressure. Considering that sulfate components occur extensively in carbonatite-related deposits, the fluid–fluid immiscibility can result in significant sulfate fractionation and provides implications for understanding the formation of carbonatite-related rare earth deposits.     

Composition of Hydrocarbons in Synthetic Diamonds Grown in a Fe—Ni—C System (according to Gas Chromatography—Mass Spectrometry Data)

The first data of chromatography—mass spectrometry analysis of volatiles from crystals of synthetic diamonds grown in a Fe—Ni—C system at 1350–1400°С and 5.5–6.0 GPa are presented. The composition of the fluid in equilibrium with the metal-carbon melt is determined, and a comparative estimation for the compounds of different hydrocarbons and their derivatives is made. It is shown that a significant role in these processes is played by high-molecular-weight hydrocarbons; and the total share of hydrocarbons and their derivatives in the fluid compounds can exceed 86%.     

Permeability Heterogeneity in a Fractured Sandstone–Mudstone Rock Mass in Xiaolangdi Dam Site, Central China

Abstract: Heterogeneity of permeability in fractured media is a hot research topic in hydrogeology. Numerous approaches have been proposed to characterize heterogeneity in the last several decades. However, little attention has been paid to correlate permeability heterogeneity with geological information. In the present study, several causes of permeability heterogeneity, that is, lithology, tectonism, and depth, are identified. The unit absorption values (denoted as ω), which are results obtained from the packer test, are employed to represent permeability. The variability of permeability in sandstone–mudstone is so significant that the value of unit absorptions span 3–4 orders of magnitude at any depth with several test sections. By declustering, it has been found that under a similar tectonic history, the means of permeability differ greatly at different formations as a result of different mudrock contents. It has also been found that in the same formation, permeability can be significantly increased as a result of faulting. The well-known phenomenon, the decrease in permeability with depth, is found to be caused by the fractures in the rock mass, and the relationship between permeability and depth can be established in the form of logω–logd. After subtracting the trend of ω with absolute depth, the mean of the residual value at each relative depth can be well correlated with the distribution of mudstone. The methods proposed in this paper can be utilized to research in similar study areas.     

Ecological–Biogeochemical Monitoring of a Linden Avenue in a Megapolis

Ecological–biogeochemical monitoring of a linden avenue on Kosygin Street, Moscow, has revealed that soils at sites regarded as contaminated contain elevated Mn, Fe, Sr, and Se concentrations and lower Zn contents. Linden leaves at the assumed contaminated sites typically contain higher Cu and Fe concentrations and not as much higher Zn, As, and Cr concentrations but much lower Mn and Sr concentrations. Water leachates of soils at sites regarded as background have slightly lower pH and lower Ca, Mg, K, and Na concentrations and total mineralization. Test for phytochelatins in the leaves proved to be rather ineffective, as also were estimates of the fluctuating asymmetry of the leaf laminas. The greatest differences were detected in the degree of leaf pathology and the contents of pigments.     

Factors and Trends in the Formation of Natural–Technogenic Associations of Polycyclic Aromatic Hydrocarbons in the Snow–Soil System

Doklady Earth Sciences - The content of polycyclic aromatic hydrocarbons (PAHs) in soil and snow cover near the carbon black plants in Moscow, Omsk, and Samara regions was studied. The differences...     

Daily Course of CO2 Fluxes in the Atmosphere–Water System and Variable Fluorescence of Phytoplankton during the Open-Water Period for Lake Baikal according to Long-Term Measurements

The process of gas exchange of CO₂ in the atmosphere–water system and its relation to the daily course of variable fluorescence of phytoplankton is studied on the basis of long-term (2004–2014) measurements during the open water period for Lake Baikal. It is found that the decrease in photosynthetic activity of plankton is almost synchronous to the increase in the CO₂ flux from atmosphere to water. It follows from comparison of the spring and summer data with December measurements that the daily decrease in variable fluorescence of phytoplankton is caused by the internal daily rhythm of the photosynthetic activity of plankton.

     

Gold Solubility in SiO2—HCl—H2O System at 200℃：a Preliminary Assessment of the Implications of Silicification with Regard to Gold Mineralization

The complexation between gold and silica was experimentally, confirmed and calibrated at 200 °C: $$\begin{gathered} Au^ + + H_3 SiO_4^ - \rightleftharpoons AuH_3 SiO_4^0 \hfill \\ \log K_{(200^\circ C)} = 19.26 \pm 0.4 \hfill \\ \end{gathered} $$ Thermodynamic calculations show that AuH₃SiO ₄ ⁰ would be far more abundant than AuCl ₂ ^? under physicochemical conditions of geological interest, suggesting that silica is much more important than chloride as ligands for gold transport. In systems containing both sulfur and silica, AuH₃SiO ₄ ⁰ would be increasingly more important than Au (HS) ₂ ^? as the proportion of SiO₂ in the system increases. The dissolution of gold in aqueous SiO₂ solutions can be described by the reaction: $$\begin{gathered} Au + 1/4O_2 + H_4 SiO_4^0 \rightleftharpoons AuH_3 SiO_4^0 + 1/2H_2 O \hfill \\ log K_{(200^\circ C)} = 6.23 \hfill \\ \end{gathered} $$ which indicates that SiO₂ precipitation is an effective mechanism governing gold deposition, and thus explains the close association of silicification and gold mineralization.     

Estimation of the Buffer Properties of Natural Waters with Account for the Acid–Base Characteristics of Humic Substances

The influence of the acid–base properties of humic substances in natural waters on the buffer capacity value is considered. An alternative way of calculation of the ANC parameter taking into account the dual nature of the humus organic of waters is proposed. Zonal aspects of the distribution of natural waters over ANC values are evaluated, and the features affecting these parameters are singled out.     

Distribution of monoalkylbenzenes C12H18–C27H48 in Vendian–Cambrian oils of the Siberian Platform

The peculiarities of the distribution of high-molecular normal alkylbenzenes in Vendian–Cambrian oils of the Siberian Platform were studied according to GC-MS data. A predominance of high-molecular homologues with the odd number of carbon atoms in the molecule has been established. Possible biochemical precursors and the probable mechanism of formation of “odd” monoalkylbenzenes are considered.     

X-ray photoelectron study of oxygen bonding in crystalline C–S–H phases

We recorded the photoelectron spectra of various crystalline calcium silicate hydrates (C–S–Hs) and have examined their O 1 s photoelectron spectra. The spectra are asymmetric, with contributions assigned primarily to bridging and non-bridging oxygen species. There is an increased contribution due to the presence of non-bonding oxygen atoms with increasing calcium:silicon ratio. Additionally, there are slight changes in theO 1s-binding energies with changes in calcium:silicon ratio. These changes are explained in terms of bonding and silicate structure.     

Transport and Crystallization of Noble Platinum in Supercritical C–O–H Fluid

Experimental data is provided for the transport of platinum in a supercritical C–O–H fluid system. The transfer of platinum in space with its condensation on the surface of native carbon (diamond and amorphous carbon) in the form of micro- and nanocrystals, shapeless particles, and filamentous formations is established for the first time. The dominant participation of platinum in the formation of carbon micro- and nanotubes is demonstrated. The results are important in modeling the formation of noble metal deposits with deep fluid carbon systems.     

Properties of a diffuse interface model based on a porous medium theory for solid–liquid dissolution problems

In this paper, a local non-equilibrium diffuse interface model is introduced for describing solid–liquid dissolution problems. The model is developed based on the analysis of Golfier et al. (J Fluid Mech 457:213–254, 2002) upon the dissolution of a porous domain, with the additional requirement that density variations with the mass fraction are taken into account. The control equations are generated by the upscaling of the balance equations for a solid–liquid dissolution using a volume averaging theory. This results into a diffuse interface model (DIM) that does not require an explicit treatment of the dissolving interface, e.g., the use of arbitrary Lagrangian–Eulerian (ALE) methods, for instance. Test cases were performed to study the features and influences of the effective coefficients inside the DIM. In particular, an optimum expression for the solid–liquid exchange coefficient is obtained from a comparison with the referenced solution by ALE simulations. Finally, a Ra–Pe diagram illustrates the interaction of natural convection and forced convection in the dissolution problem.     

Magnetic–hydrophobic coagulation of paramagnetic minerals: a correlation of theory with experiments

A simple theoretical model of magnetic–hydrophobic coagulation considering the total interaction potential energy between two spheres exposed to an external magnetic field as a sum of the van der Waals, electrostatic, magnetic, and hydrophobic components is proposed. The model was used to interpret experiments on coagulation of fine siderite particles in distilled water and 10⁻² M KCl, hydrophobized by sodium oleate. In the experiments, a relative extent of the coagulation/stability equilibrium of the siderite suspension was evaluated photoelectrically. To estimate the model parameters, the ζ-potential and hydrophobicity of siderite particles were measured.A qualitative agreement was obtained between the model predictions (energy maximum and secondary minimum) and the experimental results (voltage changes after a selected interval of sedimentation) of the siderite suspensions. Moreover, a statistically significant correlation was found between the experimental voltages and the calculated energy maximum (a crucial factor of theories on the fine particle coagulation kinetics), which can be represented by a linear regression equation with the correlation coefficient of 0.979.