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  Subjects -> ENGINEERING (Total: 2235 journals)
    - CHEMICAL ENGINEERING (188 journals)
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    - ELECTRICAL ENGINEERING (102 journals)
    - ENGINEERING (1194 journals)
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CHEMICAL ENGINEERING (188 journals)                  1 2     

AATCC Journal of Research     Full-text available via subscription   (Followers: 4)
ACS Sustainable Chemistry & Engineering     Hybrid Journal  
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials     Hybrid Journal   (Followers: 6)
Acta Polymerica     Hybrid Journal   (Followers: 7)
Additives for Polymers     Full-text available via subscription   (Followers: 20)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 5)
Advanced Chemical Engineering Research     Open Access   (Followers: 11)
Advanced Powder Technology     Hybrid Journal   (Followers: 16)
Advances in Applied Ceramics     Partially Free   (Followers: 4)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 19)
Advances in Chemical Engineering and Science     Open Access   (Followers: 26)
Advances in Polymer Technology     Hybrid Journal   (Followers: 11)
African Journal of Pure and Applied Chemistry     Open Access   (Followers: 5)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 9)
Annual Review of Chemical and Biomolecular Engineering     Full-text available via subscription   (Followers: 10)
Anti-Corrosion Methods and Materials     Hybrid Journal   (Followers: 4)
Applied Petrochemical Research     Open Access   (Followers: 3)
Asia-Pacific Journal of Chemical Engineering     Hybrid Journal   (Followers: 6)
Biochemical Engineering Journal     Hybrid Journal   (Followers: 10)
Biofuel Research Journal     Open Access   (Followers: 3)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 8)
Brazilian Journal of Chemical Engineering     Open Access   (Followers: 3)
Bulletin of Chemical Reaction Engineering & Catalysis     Open Access  
Bulletin of the Chemical Society of Ethiopia     Open Access   (Followers: 3)
Carbohydrate Polymers     Hybrid Journal   (Followers: 9)
Catalysts     Open Access   (Followers: 8)
ChemBioEng Reviews     Full-text available via subscription  
Chemical and Engineering News     Free   (Followers: 7)
Chemical and Materials Engineering     Open Access   (Followers: 2)
Chemical and Petroleum Engineering     Hybrid Journal   (Followers: 11)
Chemical and Process Engineering     Open Access   (Followers: 4)
Chemical and Process Engineering Research     Open Access   (Followers: 6)
Chemical Communications     Full-text available via subscription   (Followers: 37)
Chemical Engineering & Technology     Hybrid Journal   (Followers: 27)
Chemical Engineering and Processing: Process Intensification     Hybrid Journal   (Followers: 11)
Chemical Engineering and Science     Open Access   (Followers: 3)
Chemical Engineering Communications     Hybrid Journal   (Followers: 11)
Chemical Engineering Journal     Hybrid Journal   (Followers: 24)
Chemical Engineering Research and Design     Hybrid Journal   (Followers: 20)
Chemical Engineering Research Bulletin     Open Access   (Followers: 1)
Chemical Engineering Science     Hybrid Journal   (Followers: 18)
Chemical Geology     Hybrid Journal   (Followers: 11)
Chemical Papers     Hybrid Journal   (Followers: 3)
Chemical Product and Process Modeling     Hybrid Journal   (Followers: 3)
Chemical Reviews     Full-text available via subscription   (Followers: 131)
Chemical Society Reviews     Full-text available via subscription   (Followers: 38)
Chemical Technology     Open Access   (Followers: 5)
ChemInform     Hybrid Journal   (Followers: 3)
Chemistry & Industry     Hybrid Journal   (Followers: 2)
Chemistry Central Journal     Open Access   (Followers: 7)
Chemistry of Materials     Full-text available via subscription   (Followers: 135)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 8)
ChemSusChem     Hybrid Journal   (Followers: 8)
Chinese Chemical Letters     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Engineering     Full-text available via subscription   (Followers: 3)
Chinese Journal of Chemical Physics     Hybrid Journal   (Followers: 2)
Coke and Chemistry     Hybrid Journal  
Coloration Technology     Hybrid Journal   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 9)
Computer Aided Chemical Engineering     Full-text available via subscription   (Followers: 2)
Computers & Chemical Engineering     Hybrid Journal   (Followers: 9)
CORROSION     Full-text available via subscription   (Followers: 20)
Corrosion Engineering, Science and Technology     Hybrid Journal   (Followers: 39)
Corrosion Reviews     Hybrid Journal   (Followers: 5)
Crystal Research and Technology     Hybrid Journal   (Followers: 2)
Current Opinion in Chemical Engineering     Open Access   (Followers: 3)
Education for Chemical Engineers     Hybrid Journal   (Followers: 4)
Eksergi     Open Access  
Emerging Trends in Chemical Engineering     Full-text available via subscription  
European Polymer Journal     Hybrid Journal   (Followers: 44)
Fibers and Polymers     Full-text available via subscription   (Followers: 3)
Fluorescent Materials     Open Access   (Followers: 1)
Focusing on Modern Food Industry     Open Access   (Followers: 3)
Frontiers of Chemical Science and Engineering     Hybrid Journal   (Followers: 1)
Gels     Open Access  
Geochemistry International     Hybrid Journal  
Handbook of Powder Technology     Full-text available via subscription   (Followers: 3)
Heat Exchangers     Open Access   (Followers: 1)
High Performance Polymers     Hybrid Journal  
Hungarian Journal of Industry and Chemistry     Open Access  
Indian Chemical Engineer     Hybrid Journal   (Followers: 4)
Indian Journal of Chemical Technology (IJCT)     Open Access   (Followers: 11)
Indonesian Journal of Chemical Science     Open Access   (Followers: 1)
Industrial & Engineering Chemistry     Full-text available via subscription   (Followers: 10)
Industrial & Engineering Chemistry Research     Full-text available via subscription   (Followers: 20)
Industrial Chemistry Library     Full-text available via subscription   (Followers: 4)
Info Chimie Magazine     Full-text available via subscription   (Followers: 2)
International Journal of Chemical and Petroleum Sciences     Open Access   (Followers: 2)
International Journal of Chemical Engineering     Open Access   (Followers: 7)
International Journal of Chemical Reactor Engineering     Hybrid Journal   (Followers: 3)
International Journal of Chemical Technology     Open Access   (Followers: 4)
International Journal of Chemoinformatics and Chemical Engineering     Full-text available via subscription   (Followers: 2)
International Journal of Food Science     Open Access   (Followers: 4)
International Journal of Industrial Chemistry     Open Access  
International Journal of Polymeric Materials     Hybrid Journal   (Followers: 4)
International Journal of Science and Engineering     Open Access   (Followers: 7)
International Journal of Waste Resources     Open Access   (Followers: 5)
Journal of Chemical Engineering & Process Technology     Open Access   (Followers: 3)
Journal of Applied Crystallography     Hybrid Journal   (Followers: 5)
Journal of Applied Electrochemistry     Hybrid Journal   (Followers: 11)

        1 2     

Journal Cover Geochemistry International
  [SJR: 0.491]   [H-I: 14]   [0 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1556-1968 - ISSN (Online) 0016-7029
   Published by Springer-Verlag Homepage  [2280 journals]
  • Genesis of volatile components at Saturn’s regular satellites.
           Origin of Titan’s atmosphere
    • Abstract: Abstract Jupiter’s and Saturn’s regular satellites, which posses much ice, are currently thought to have been formed during the early evolution of the Solar System in circumplanetary protosatellite disks. Two of Saturn’s regular satellites—Titan and Enceladus—were experimentally proved to contain, along with water, other volatile components: molecular nitrogen, and methane (which are the major components of Titan’s atmosphere) and various nitrogen and carbon compounds in water plumes of Enceladus. The protomaterial of these rocky–icy satellites was formed in the outer regions of the gas–dust circumsolar nebula, and its closest analogue currently accessible to study is cometary material. The paper presents a review of experimental data on the chemical and isotopic composition of cometary material as possible sources of volatile components on Titan and Enceladus and model evaluations of temperatures in the circumsolar gas–dust protoplanetary disk and Jupiter’s and Saturn’s protosatellite disks during various evolutionary episodes of the solar system. The P–T parameters of the origin of the protomaterial of Jupiter’s and Saturn’s regular satellites were proved to have been remarkably different, and hence, the material of Europa, a Jupiter’s regular satellite, cannot contain any volatile components other than water, in contrast to Titan and Enceladus. This conclusion is supported by experimental data. Cometary material is likely genetically related to the material of Saturn’s regular satellites Titan and Enceladus. The paper presents results of thermodynamic simulation of the evolution of the chemical and phase composition of Saturn’s satellites and suggests a model for the origin of Titan’s nitrogen–methane atmosphere.
      PubDate: 2016-01-01
       
  • Trace element composition and Lu-Hf isotope systematics of zircon from
           plagiogneisses of the Kola superdeep well: Contribution of a Paleoarchean
           crust in Mesoarchean metavolcanic rocks
    • Abstract: Abstract Zircons have been studied in three samples of Archean plagiogneisses from the Kola superdeep well (SG-3). The crystals consist of cores, magmatic shells, and metamorphic rims. The cores and shells are characterized by similar lowered concentrations of most trace elements, which is typical of zircons from plagiogranitoids, rocks of elevated basicity, and basites. At a wide range of Hf isotope characteristics, the cores and shells have similar average 176Hf/177Hfi, which determines the close composition of their sources. The metamorphic rims have close 176Hf/177Hfi ratio. The minimum age of the crustal contaminant of parental melts is estimated at 3.4 and 3.3 Ga for cores and 3.3–3.2 Ga for shells at almost equal proportions of mantle and crustal components in them. The contribution of Paleoarchean crust established in zircons from plagiogneisses of SG-3 using Lu-Hf isotope systematics is confirmed by the presence of 3.3and 3.4-Ga old zircons in surrounding TTG.
      PubDate: 2016-01-01
       
  • Effects of water acidification on element concentrations in natural waters
           of the Kola North
    • Abstract: Abstract This study discusses the problem of evolution of water chemistry under the influence of acid loadings from copper–nickel smelters of the Kola mining and smelting company (“KGMK”). The natural waters of the Kola Peninsula are characterized by low contents of biogenic substances and mineral salts owing to low water temperatures and low mass transfer rates at high latitudes. Acid precipitation causes water acidification in regions made up by granite gneisses and sandy rocks. Unlike naturally acidic waters with high humic acid contents, these lakes have high-transparency waters. The results show that Cd, Bi, Se, and Re become involved in the transport fluxes irrespective of a natural or anthropogenic source of acidification. Acidified lakes have higher Zn, Pb, As, Bi, and Sb contents compared to neutral lakes. The high coefficient of aqueous migration of Se, Re, Bi, Sb, Cd, and Sn is indicative of the anthropogenically-induced dispersal of these elements.
      PubDate: 2016-01-01
       
  • Discriminant and factor analyses as tools for comparison of terrestrial
           and Venusian volcanic rocks
    • Abstract: Abstract Statistical methods of multi-dimensional analysis (discriminant functions and factor analysis) were applied to compare the chemical analyses obtained by Venera-13, -14, and Vega-2 landers (contents of major oxides except for sodium) with petrochemical data compiled into the data base on terrestrial ocean. It is shown that the distribution of major petrogenic elements in the terrestrial rocks ascribed to different geodynamic settings (spreading zones, hot spots, and subduction zones) is determined by crystallization differentiation. This process is best manifested in hot spot volcanics (volcanic islands). In spite of the difficulties related to the poor precision of chemical determinations of Venusian rocks, obtained data indicate that the rocks from the Venera-13 and Vega-2 landing sites have no petrochemical analogues among terrestrial oceanic volcanic rocks. Rocks analyzed in the Venera-14 landing site may resemble the mid-ocean ridge volcanic rocks, although geological setting in the Venera-14 landing site ellipse strongly differs from terrestrial spreading zones.
      PubDate: 2016-01-01
       
  • Microtexture, nanomineralogy, and local chemistry of cryptocrystalline
           cosmic spherules
    • Abstract: Abstract The paper reports scanning electron microscopy (FEG-SEM) and transmission electron microscopy (TEM) data on three cryptocrystalline (CC) cosmic spherules of chondritic composition (Mg/Si ≈ 1) from two collections taken up at glaciers at the Novaya Zemlya and in the area of the Tunguska event. The spherules show “brickwork” microtextures formed by minute parallel olivine crystals set in glass of pyroxene–plagioclase composition. The bulk-rock silicate chemistry, microtexture, mineralogy, and the chemical composition of the olivine and the local chemistry of the glass in these spherules testify to a chondritic source of the spherules. The solidification of the spherules in the Earth’s atmosphere was proved to be a highly unequilibrated process. A metastable state of the material follows, for example, from the occurrence of numerous nanometer-sized SiO2 globules in the interstitial glass. These globules were formed by liquid immiscibility in the pyroxene–SiO2 system. Troilite FeS and schreibersite (Fe,Ni)3P globules were found in the FeNi metal in one of the spherules, which suggests that the precursor was not chemically modified when melted in the Earth’s atmosphere. Our results allowed us to estimate the mineralogy of the precursor material and correlate the CC spherules with the chondrule material of chondrites. The bulk compositions of the spherules are closely similar to those of type-IIA chondrules.
      PubDate: 2016-01-01
       
  • Physico-chemical models of the internal structure of partially
           differentiated Titan
    • Abstract: Abstract We analyze models of the internal structure of Titan, a large icy satellite of the Saturn system. Calculations are carried out using information on the mass, mean density, moment of inertia, orbital parameters, and elastic properties of the satellite obtained by the Cassini–Huygens mission, as well as geochemical data on the composition of chondrite materials, equations of state of water and ices I, III, V, VI, and VII, and thermodynamic models for conductive heat transfer in the outer icy crust and of global convection in the interior zones of the satellite. The analysis of the models shows that models of partially differentiated Titan are most consistent; they include an outer water–ice shell, an intermediate ice–rock mantle, and an inner rock–iron core. It is shown that for the models of this type the maximum thickness of the water–ice shell is 460–470 km; it can be composed of an outer conductive crust of Ih ice 80–110 km thick and a subsurface water ocean 200–300 km deep. The maximum radius of the central rock–iron core of Titan can reach ~1300 km. The thickness of Titan’s ice–rock mantle does not exceed 2100 km at a density of 1.22–2.64 g/cm3. The model of partially differentiated Titan is feasible in the moment of inertia range of 0.312 < I/MR 2 < ~0.350.
      PubDate: 2016-01-01
       
  • Formation and sorption behavior of the palladium thiosulfate complexes
           under natural conditions (model experiments)
    • Abstract: Abstract The formation of significant amounts of thiosulfate ion (up to 42 mg/L) was established in experiments on the interaction of sulfide-bearing rocks with water. The possibility of the formation of palladium compounds with thiosulfate ion [Pd(S2O3)2]2– was demonstrated. The stability constant of the complex is 3.7 × 109, which may provide intense migration of this palladium species in ecosystem. The study of the behavior of palladium thiosulfates during interaction with inorganic and organic components of geochemical barriers showed that around 50–55% of thiosulfate-bound palladium is extracted by humic acid in the pH range typical of natural waters. Under these conditions, ferrihydrite sorbes palladium quantitatively, and may serve as efficient barrier to the interaction of palladium compounds with particulate matters of waters and bottom sediments.
      PubDate: 2016-01-01
       
  • Geochemistry of fractionation of coherent elements (Zr and Hf) during the
           profound differentiation of peralkaline magmatic systems: A case study of
           the Lovozero Complex
    • Abstract: Abstract The paper presents pioneering data on Hf distribution in peralkaline rocks, ores, and rock-forming and accessory minerals of the Lovozero Complex. Variations in the Zr/Hf ratio are determined in all rocks of the Lovozero alkaline massif. This ratio is proved to increase in the course of evolution of alkaline magma because of fractionation of alkaline pyroxene. The Hf distribution coefficient is evaluated for alkali-rich pyroxene, whose crystallization controls Zr and Hf fractionation during the differentiation of alkaline magma. These data and the equation of equilibrium and fractional crystallization are utilized in a model suggested for Zr and Hf fractionation in the course of evolution of the Lovozero intrusion.
      PubDate: 2016-01-01
       
  • Long-term galactic cosmic ray variations over the last billion years based
           on the cosmic-ray exposure ages of iron meteorites
    • Abstract: Abstract The distribution of the cosmic-ray exposure ages (T) of iron meteorites was analyzed to establish the possible variations in the intensity of the galactic cosmic ray (GCR) over the last billion years. The analysis was made for the entire data set containing ~80 age values from the literature (Voshage et al., 1983) and the corrected set after the exclusions of paired meteorites (using the Akaike information criterion). The dependence of the criterion χ2 in the distribution of the phase values Ph = T/t–int(T/t) on the values of the assumed period (t) of GCR variations was analyzed for both sets of meteorites. The significant deviations of these parameters from the respective average values were found for t ~ 400–500 Myr and, in part, for t ~ 150 Myr. These deviations were interpreted by numerical modeling using the values of ages randomly distributed in the range of 0–1000 Ma. It was found that for variations with a period of 450 Myr, the distribution of the phase values and cosmic-ray exposure ages in the model data set is similar to that of iron meteorites. These results testify to the existence of the GCR variations with a period of ~400–500 Myr during the last 1 Gyr. The variations in the GCR flux can be explained by periodic galactic spiral arm crossings of the solar system. The GCR variations with a period of ~150 Myr discussed in the previous studies (Shaviv, 2002; 2003; Scherer et al., 2006) appears to be less certain.
      PubDate: 2016-01-01
       
  • Intentions and failures. Fundamental space investigations in Russia of the
           last twenty years. Twenty years of fruitless efforts
    • Abstract: Abstract This contribution provides the history of Russian planetary exploration over the past 15–20 years. Despite particular interesting ideas and accomplishments, little encouragement can be derived from those activities. Over these years, no lunar and planetary missions took place in Russia, whereas the United States, European countries, China, Japan, and India sent dozens of spacecrafts, which allowed them to make considerable progress in the exploration of the solar system. Despite hefty funding, none of three deep space astrophysical observatories of the Spektr series was launched. The main reasons for this—incompetence and lack of responsibility—are just part of an overall disturbing trend, which can be observed not only in space activities but also in many other parts of our life. Therefore, this book is not only targeted at specialists from the space sector and science, but will also be useful to many readers who are interested in the situation in their own country. The author hopes this book will help those who want to learn lessons from painful failures and provide basis for improving management practices in the future.
      PubDate: 2015-12-01
       
  • A new geochemical perspective on hydrochemical evolution of the Tibetan
           geothermal system
    • Abstract: Abstract The uplift of the Tibetan Plateau has caused the development of many high-enthalpy geothermal fields that are rich in exploitable rare and dispersed resource elements. However, the mechanism of the unusual enrichment of these resource elements is still unclear. From a geochemical viewpoint, including major chemical compositions, some rare and dispersed resource elements and trace elements in geothermal water and some river samples from the northern Lhasa block (saline lake area), the southern Lhasa block (Gangdise volcanic belt) and Tethyan Himalaya in Tibet, this study provides new insights into the mechanism of the hydrochemical evolution of the Tibetan geothermal system. The Cl-type geothermal waters in the Gangdise volcanic belt and Tethyan sedimentary area show similar chemical characteristics that are apparently different from that of surface cold waters. The concentrations of Sb, Tl, As, K, Cs, Li, Rb, Ga, B, Cl, Th, Sc, Mn, V, and Ti in Cl-type geothermal waters are at least one order of magnitude higher than those in surface cold waters, but the concentrations of Ca, Mg, Ni, Cr, Zn, Fe, Co, Cu, Pb, and U in Cl-type geothermal waters are slightly higher or even lower than those in surface cold waters. Some rivers and streams in Tibet also show high concentrations of toxic elements. These rivers and streams are mainly polluted by geothermal spring discharge and are unsuitable for drinking. Some ions and elements (such as Ca, Mg, Ba, Sr, SO 4 2− and Mn) in HCO 3 − —type geothermal waters from sedimentary rocks are affected by the availability of soluble minerals such as calcite, dolomite and gypsum. However, the other dissolved elements in HCO 3 − –type geothermal waters show the characteristic of mixing Cl-type geothermal waters with surface cold waters. The origin of deep fluids in Cl− and HCO 3 − —type springs is related, and this origin probably involves the contribution of crustal partial melting rather than single rock leaching. Thus, deep circulating groundwater mixes with residual magmatic fluids and evolves into the unusual enrichment of geothermal mineral resources.
      PubDate: 2015-12-01
       
  • Vaporization coefficients of oxides contained in the melts of
           Ca-Al-inclusions in chondrites
    • Abstract: Abstract Based on the analysis of theoretical and experimental data, the following vaporization coefficients are suggested for crystalline oxides contained in Ca-Al-inclusions in chondrites: 0.66 ± 0.15 for CaO, 0.50 ± 0.20 for MgO, 1.00 ± 0.20 for FeO, 0.33 ± 0.02 for Al2O3, 0.23 ± 0.02 for TiO2, and (2.2 ± 0.3) × 10−2 for SiO2. For vaporization from liquids, the coefficients of these oxides found in the Ca-Al-inclusions are equal to one, which is confirmed by the consistency of experimental data and thermodynamic calculations for changes in the composition of multicomponent oxide melts during vaporization.
      PubDate: 2015-12-01
       
  • Metastable solubilities of mineral SrSO 4 scale in NaCl solution at 298.2
           K
    • PubDate: 2015-12-01
       
  • Hydrocarbons from a volcanic area. Oil seeps in the Uzon caldera,
           Kamchatka
    • Abstract: Abstract The isotope and hydrocarbon compositions of oil seeps in the caldera of Uzon Volcano were investigated. An experiment was conducted to simulate the thermal hydrolysis of biota in the hot springs of the caldera, which is considered as a source of carbon for the oil seeps. The same methods were applied to investigate petroleum condensate and thermal gases (CH4 and CO2) from a well in the Bogachevka field adjacent to the Uzon caldera. The measured carbon isotope composition of oils from the Uzon caldera (δ13C of −31.24 and −31.47‰) is typical of oils derived from biological materials of mostly bacterial origin. The low content of tricyclic terpanes, which is a qualitative oil maturity parameter, indicates that the oil maturity of the Uzon seeps is low. In the gas samples, the δ13C of CO2 ranges from −6.5 to −0.18‰ averaging approximately −2.8‰. The δ13C of methane is from −30.13 to −19.03‰ averaging approximately −24.0‰. A difference was detected between the isotopic fractionation characteristics of naphtides from the Uzon caldera and products of the thermal hydrolysis of biota. In turn, the isotopic fractionation characteristic of thermally hydrolyzed biota appeared to be similar to the proportion of the isotopic compositions of the respective fractions of Bogachevka oil. The identical isotopic diagrams of the Bogachevka oil and the hydrothermally transformed biota confirm the biogenic nature of the Bogachevka oil. Hydrocarbons from the Uzon caldera (Kamchatka) are mainly products of the hydrothermal transformation of the biomass of microorganisms and plant remains in the zone of thermal water circulation.
      PubDate: 2015-12-01
       
  • Species and environmental geochemistry characteristics of organic
           phosphorus in sediments of a riverine wetland measured by 31 P-NMR
           spectroscopy
    • Abstract: Abstract Phosphorus species in sediment cores obtained from a representative riverine wetland were determined and organic phosphorus was distinguished with phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy. The concentrations and distributions of orthophosphate, orthophosphate monoester, orthophosphate diester and pyrophosphate were subsequently characterized. Total phosphorus, total inorganic phosphorus and total organic phosphorus decreased from the top to bottom layer of sediment on the whole. Organic phosphorus was primarily detected in surface sediment layers and scarce toward the bottom, and orthophosphate as a proportion of total organic phosphorus was much higher than other species which was attributed to mineralization as a result of high dissolved oxygen (DO) concentrations. Furthermore, significant positive correlation was observed between alkaline phosphatase activity (APA) and phosphorus fractions suggesting that APA could hydrolyze organic phosphorus into inorganic phosphorus even at high phosphorus concentrations. Significant correlation was also observed between Fe/Al and phosphorus species showed organic phosphorus adsorbed to Fe/Al might be released from sediments and transformed to inorganic phosphorus.
      PubDate: 2015-12-01
       
  • Geochemistry of Rohtas Limestone from Vindhyan Supergroup, Central India:
           Evidences of detrital input from felsic source
    • Abstract: Abstract The Rohtas Limestone of Semri Group is conformably overlain by Lower Kaimur Group of Vindhyan Supergroup in the Son Valley, Central India. Lower Kaimur Group comprising Sasaram Sandstone, Ghurma Shale and Markundi Sandstone are dominantly quartz arenite in composition. While, Rohtas limestones are micritic carbonates with considerable input of detrital grains/rock fragments. Major oxide data shows that Lower Kaimur sandstone have SiO2 = 92 wt % while limestone exhibit SiO2 = 9.52 wt %, CaO = 47 wt %. Limestones exhibit Sr = 352 ppm, Zr = 20 ppm, while Lower Kaimur sandstones are enriched in Zr = 400 ppm, due to the presence of heavy minerals like zircon. The average limestone and sandstone shows a fractionated LREE pattern and a nearly flat HREE pattern with a small negative Eu anomaly. REE patterns and abundance of limestone are quite similar and comparable to sandstones from Lower Kaimur than to the pure micritic limestone. This indicates that the REE pattern and abundance of Rohtas limestone have been controlled by detrital components possibly derived from the similar source as that for Lower Kaimur sandstones. Apart from the similarity in the REE patterns of limestone and sandstone, the trace element ratios such as Ti/Zr, La/Sc, Th/Sc, Th/Co, Th/U, Zr/Sc, Ba/Sr, La/Th, La/Th, Zr/Hf, [La/Yb]N, [Ce/Yb]N, [Gd/Yb]N, [Sm/Nd]N, [La/Lu]N and Eu/Eu* strongly support the above inference. The ubiquitously comparable REE patterns and incompatible elemental ratios of Rohtas limestones and Lower Kaimur sandstones indicate their derivation from a similar felsic source. The geochemical signatures suggest that the Bundelkhand Gneissic Complex had significantly contributed sediments to the Vindhyan basin prior and during the deposition of Lower Kaimur Group.
      PubDate: 2015-12-01
       
  • Organic carbon and carbonates in the recent bottom sediments of the Kerch
           Strait
    • Abstract: Abstract Data on the abundance and distribution of organic carbon and carbonates in the recent bottom sediments of the Kerch Strait were analyzed. It was shown that the content of organic carbon in the bottom sediments of the navigable part of the strait adjacent to the Kerch Peninsula is currently 1.5–2.0 times higher than the values obtained in the 1970s and organic carbon contents in the modern bottom sediments from the part of the strait adjacent to the Taman Peninsula. This is explained by the spatial distribution of the grain-size composition of bottom sediments in the strait and changes in the sedimentation conditions due to anthropogenic activities. As possible environmental consequences of such changes, we discussed the formation of hypoxia zones and increasing risk of asphyxiation phenomena in the strait.
      PubDate: 2015-12-01
       
  • Geochemical trends of gabbro and granites in the Urals: Evidence of the
           evolutionary history of the mobile belt
    • Abstract: Abstract Principal geochemical features of gabbro and granites in the Urals, the two dominant rock groups of cotectic composition, most adequately reflect the dependences of the composition of the rocks on geological environment, which varied during the evolution of the orogen. The main geochemical trend of the gabbroids is proved to have an age coordinate and was controlled by the progressively more intense metasomatic modification of the mantle wedge as the major source of mafic magmas. The trend reflects the process that can be provisionally defined as “continentalization”. The gabbroids older than 380 Ma tend to plot within the composition field of the oceanic crust (roughly corresponding to N-MORB), whereas younger gabbroids (whose dominant mafic mineral is hornblende) plot within the field of continental mafic rocks. The behavior of such lithophile elements as K and Rb, whose concentrations increase in the course of rock evolution, unambiguously testifies that the trend corresponds to the evolution of the rocks from mafic to acid with time. During the “continentalization” of the mobile belt, the fertility of the magmatic source of the mafic rocks (mantle wedge) increased because of the progressively enhanced metasomatism of the wedge by fluid. Much of this fluid was generated in the subduction zone via the dehydration of hydroxyl-bearing minerals. In the Late Devonian, the dominant source of the fluid was amphibole in amphibolites (metamorphosed basites) and serpentine, and later the relative role of sediments involved in the subduction zone increased. The age trend is almost not reflected in the geochemistry of the granites, and their major geochemical trend can be defined as spatial. The obvious geochemical specifics of the Permian collisional granites in the northwestern and southeastern megablocks were controlled by compositional variations in the source material. Along with the newly-formed crust, the magmatic sources of granites in the northwestern megablock contained much rocks of the Mesoproterozoic granite–gneiss basement, whereas the sources of granites in the southeastern megablock was dominated by orthogneisses, which are metamorphic rocks of Paleozoic gabbro–tonalite–granodiorite–granite series.
      PubDate: 2015-12-01
       
  • The nature of xenoliths in the Novaya Melovatka intrusion, Voronezh
           Crystalline Massif
    • Abstract: Abstract The paper presents petrographic and petrochemical data on metaterrigenous (comparable with rocks of the Vorontsovka Group) and metamamatic ultramafic–mafic xenoliths in the Paleoproterozoic Novaya Melovatka intrusion in the Voronezh Crystalline Massif (VCM). The intrusion was drilled through by Voronezh Stratigraphic Borehole at Site 3210 of Geotraverse 1-EV. The concordant U-Pb zircon age of a gabbrodiorite xenolith is 2138 ± 25 Ma, and a rock of this age has no analogues among any other magmatic complexes in the geological legend currently adopted for VCM. The younger zircon age value of 2052 ± 22 Ma is thought to be explained by the thermal effect of the Novaya Melovatka intrusion, which was emplaced at 2049 ± 10 to 2057 ± 12 Ma. Xenoliths from this intrusion and from norite of the Elan’ Complex are petrochemically similar to one another and comparable with oceanic-type rocks (cumulus and differentiated mafic–ultramafic series). According to circumstantial evidence, the former were emplaced at relatively shallow depths of 20–30 km in the middle and lower Paleoproterozoic crust, whereas the latter were intruded into the mantle at a depth of 40–50 km, which suggests that the Voronezh block of VCM contains no Archean continental crustal component. The paper reports dada on differences between the Ni-bearing and metallogenically barren mafic–ultramafic massifs.
      PubDate: 2015-12-01
       
  • Simulation experiments on the generation of organic sulfide in the Shengli
           crude oil
    • Abstract: Abstract Shengli crude oil sample was investigated using a comprehensive method to characterize and identify the formation and distribution of the organic sulfide. A full compositional model uses an autoclave on the system of Shengli crude oil and magnesium sulfate under high temperature and pressure conditions. Gas chromatography (GC) and microcoulometry were used to describe characteristics of gas phase products. The results show that the ratio of methane in the gas composition and the content of hydrogen sulfide improved by increasing temperature, which suggested that with the reaction temperature growing, the extent of the thermochemical sulfate reduction (TSR) process is deepened gradually. With the analysis of oil phase products by fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography-pulsed-flame photometric detector (GC-PFPD), the distribution of organic sulfide can be detected in detail. The contents of organic sulfide especially as mercaptan, sulfoether and thiophene were detected by GC-PFPD. Through FT-ICR MS, sulfide species were characterized by class, type, and carbon number. The results show that, with increasing temperature, the content of mercaptan, became dramatically dominated, sulfoether and thiophene gradually increasing too. Types of sulfur compounds in the oil phase identified by FT-ICR MS are mainly S1, S2, N1S1, O1S1 and O2S1. The S1 species are the most dominated. All of the results suggest that, as the reaction temperature is growing, the evolution process of organic sulfur compounds is originally changed from thiophene series to the benzothiophene series gradually and then to dibenzothiophene series. The products of solid phases were analyzed by FT-IR and XRD. The results show that the content of sulphur in magnesium sulphate decreased. This fenomenon demonstrated transformation of inorganic sulfur compounds into organic sulfur compound. According to the reaction model, the calculated activation energy is 57.91 kJ mol−1 and the frequency factor A is 0.21 s−1.
      PubDate: 2015-12-01
       
 
 
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