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Publisher: Springer-Verlag (Total: 2573 journals)

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Showing 1 - 200 of 2573 Journals sorted alphabetically
3D Printing in Medicine     Open Access   (Followers: 4)
3D Research     Hybrid Journal   (Followers: 21, SJR: 0.222, CiteScore: 1)
4OR: A Quarterly J. of Operations Research     Hybrid Journal   (Followers: 11, SJR: 0.825, CiteScore: 1)
AAPS J.     Hybrid Journal   (Followers: 29, SJR: 1.118, CiteScore: 4)
AAPS PharmSciTech     Hybrid Journal   (Followers: 8, SJR: 0.752, CiteScore: 3)
Abdominal Radiology     Hybrid Journal   (Followers: 18, SJR: 0.866, CiteScore: 2)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 4, SJR: 0.439, CiteScore: 0)
Academic Psychiatry     Full-text available via subscription   (Followers: 30, SJR: 0.53, CiteScore: 1)
Academic Questions     Hybrid Journal   (Followers: 9, SJR: 0.106, CiteScore: 0)
Accreditation and Quality Assurance: J. for Quality, Comparability and Reliability in Chemical Measurement     Hybrid Journal   (Followers: 31, SJR: 0.316, CiteScore: 1)
Acoustical Physics     Hybrid Journal   (Followers: 11, SJR: 0.359, CiteScore: 1)
Acoustics Australia     Hybrid Journal   (Followers: 1, SJR: 0.232, CiteScore: 1)
Acta Analytica     Hybrid Journal   (Followers: 7, SJR: 0.367, CiteScore: 0)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1, SJR: 0.675, CiteScore: 1)
Acta Biotheoretica     Hybrid Journal   (Followers: 4, SJR: 0.284, CiteScore: 1)
Acta Diabetologica     Hybrid Journal   (Followers: 19, SJR: 1.587, CiteScore: 3)
Acta Endoscopica     Hybrid Journal   (Followers: 1)
acta ethologica     Hybrid Journal   (Followers: 4, SJR: 0.769, CiteScore: 1)
Acta Geochimica     Hybrid Journal   (Followers: 7, SJR: 0.24, CiteScore: 1)
Acta Geodaetica et Geophysica     Hybrid Journal   (Followers: 3, SJR: 0.305, CiteScore: 1)
Acta Geophysica     Hybrid Journal   (Followers: 11, SJR: 0.312, CiteScore: 1)
Acta Geotechnica     Hybrid Journal   (Followers: 7, SJR: 1.588, CiteScore: 3)
Acta Informatica     Hybrid Journal   (Followers: 5, SJR: 0.517, CiteScore: 1)
Acta Mathematica     Hybrid Journal   (Followers: 12, SJR: 7.066, CiteScore: 3)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2, SJR: 0.452, CiteScore: 1)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 6, SJR: 0.379, CiteScore: 1)
Acta Mathematica Vietnamica     Hybrid Journal   (SJR: 0.27, CiteScore: 0)
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal   (SJR: 0.208, CiteScore: 0)
Acta Mechanica     Hybrid Journal   (Followers: 25, SJR: 1.04, CiteScore: 2)
Acta Mechanica Sinica     Hybrid Journal   (Followers: 5, SJR: 0.607, CiteScore: 2)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7, SJR: 0.576, CiteScore: 2)
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.638, CiteScore: 1)
Acta Neurochirurgica     Hybrid Journal   (Followers: 7, SJR: 0.822, CiteScore: 2)
Acta Neurologica Belgica     Hybrid Journal   (Followers: 2, SJR: 0.376, CiteScore: 1)
Acta Neuropathologica     Hybrid Journal   (Followers: 4, SJR: 7.589, CiteScore: 12)
Acta Oceanologica Sinica     Hybrid Journal   (Followers: 3, SJR: 0.334, CiteScore: 1)
Acta Physiologiae Plantarum     Hybrid Journal   (Followers: 4, SJR: 0.574, CiteScore: 2)
Acta Politica     Hybrid Journal   (Followers: 19, SJR: 0.605, CiteScore: 1)
Activitas Nervosa Superior     Hybrid Journal   (SJR: 0.147, CiteScore: 0)
Adaptive Human Behavior and Physiology     Hybrid Journal  
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 8, SJR: 0.103, CiteScore: 0)
ADHD Attention Deficit and Hyperactivity Disorders     Hybrid Journal   (Followers: 28, SJR: 0.72, CiteScore: 2)
Adhesion Adhesives & Sealants     Hybrid Journal   (Followers: 9)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 19, SJR: 1.005, CiteScore: 2)
Adolescent Research Review     Hybrid Journal   (Followers: 1)
Adsorption     Hybrid Journal   (Followers: 5, SJR: 0.703, CiteScore: 2)
Advanced Composites and Hybrid Materials     Hybrid Journal  
Advanced Fiber Materials     Full-text available via subscription  
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 4, SJR: 0.698, CiteScore: 1)
Advances in Astronautics Science and Technology     Hybrid Journal  
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 40, SJR: 0.956, CiteScore: 2)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 21, SJR: 0.812, CiteScore: 1)
Advances in Contraception     Hybrid Journal   (Followers: 3)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 58, SJR: 1.09, CiteScore: 1)
Advances in Gerontology     Partially Free   (Followers: 8, SJR: 0.144, CiteScore: 0)
Advances in Health Sciences Education     Hybrid Journal   (Followers: 35, SJR: 1.64, CiteScore: 2)
Advances in Manufacturing     Hybrid Journal   (Followers: 3, SJR: 0.475, CiteScore: 2)
Advances in Neurodevelopmental Disorders     Hybrid Journal  
Advances in Polymer Science     Hybrid Journal   (Followers: 49, SJR: 1.04, CiteScore: 3)
Advances in Therapy     Hybrid Journal   (Followers: 5, SJR: 1.075, CiteScore: 3)
Aegean Review of the Law of the Sea and Maritime Law     Hybrid Journal   (Followers: 7)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2, SJR: 0.517, CiteScore: 1)
Aerobiologia     Hybrid Journal   (Followers: 3, SJR: 0.673, CiteScore: 2)
Aerosol Science and Engineering     Hybrid Journal  
Aerospace Systems     Hybrid Journal   (Followers: 1)
Aerotecnica Missili & Spazio : J. of Aerospace Science, Technologies & Systems     Hybrid Journal  
Aesthetic Plastic Surgery     Hybrid Journal   (Followers: 11, SJR: 0.825, CiteScore: 1)
African Archaeological Review     Hybrid Journal   (Followers: 21, SJR: 0.862, CiteScore: 1)
Afrika Matematika     Hybrid Journal   (Followers: 1, SJR: 0.235, CiteScore: 0)
Ageing Intl.     Hybrid Journal   (Followers: 7, SJR: 0.39, CiteScore: 1)
Aggiornamenti CIO     Hybrid Journal   (Followers: 1)
Aging Clinical and Experimental Research     Hybrid Journal   (Followers: 3, SJR: 0.67, CiteScore: 2)
Agricultural Research     Hybrid Journal   (Followers: 7, SJR: 0.276, CiteScore: 1)
Agriculture and Human Values     Open Access   (Followers: 15, SJR: 1.173, CiteScore: 3)
Agroforestry Systems     Open Access   (Followers: 20, SJR: 0.663, CiteScore: 1)
Agronomy for Sustainable Development     Open Access   (Followers: 15, SJR: 1.864, CiteScore: 6)
AI & Society     Hybrid Journal   (Followers: 9, SJR: 0.227, CiteScore: 1)
AIDS and Behavior     Hybrid Journal   (Followers: 16, SJR: 1.792, CiteScore: 3)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 4, SJR: 0.862, CiteScore: 3)
Akupunktur & Aurikulomedizin     Full-text available via subscription   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 7, SJR: 0.531, CiteScore: 0)
Algebra Universalis     Hybrid Journal   (Followers: 2, SJR: 0.583, CiteScore: 1)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1, SJR: 1.095, CiteScore: 1)
Algorithmica     Hybrid Journal   (Followers: 9, SJR: 0.56, CiteScore: 1)
Allergo J.     Full-text available via subscription   (Followers: 1, SJR: 0.234, CiteScore: 0)
Allergo J. Intl.     Hybrid Journal   (Followers: 2)
Alpine Botany     Hybrid Journal   (Followers: 5, SJR: 1.11, CiteScore: 3)
ALTEX : Alternatives to Animal Experimentation     Open Access   (Followers: 2)
AMBIO     Hybrid Journal   (Followers: 10, SJR: 1.569, CiteScore: 4)
American J. of Cardiovascular Drugs     Hybrid Journal   (Followers: 17, SJR: 0.951, CiteScore: 3)
American J. of Community Psychology     Hybrid Journal   (Followers: 29, SJR: 1.329, CiteScore: 2)
American J. of Criminal Justice     Hybrid Journal   (Followers: 9, SJR: 0.772, CiteScore: 1)
American J. of Cultural Sociology     Hybrid Journal   (Followers: 18, SJR: 0.46, CiteScore: 1)
American J. of Dance Therapy     Hybrid Journal   (Followers: 6, SJR: 0.181, CiteScore: 0)
American J. of Potato Research     Hybrid Journal   (Followers: 3, SJR: 0.611, CiteScore: 1)
American J. of Psychoanalysis     Hybrid Journal   (Followers: 22, SJR: 0.314, CiteScore: 0)
American Sociologist     Hybrid Journal   (Followers: 16, SJR: 0.35, CiteScore: 0)
Amino Acids     Hybrid Journal   (Followers: 7, SJR: 1.135, CiteScore: 3)
AMS Review     Partially Free   (Followers: 4)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 10, SJR: 0.211, CiteScore: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 6, SJR: 0.536, CiteScore: 1)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Analysis of Verbal Behavior     Hybrid Journal   (Followers: 6)
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 32, SJR: 0.978, CiteScore: 3)
Anatomical Science Intl.     Hybrid Journal   (Followers: 3, SJR: 0.367, CiteScore: 1)
Angewandte Schmerztherapie und Palliativmedizin     Hybrid Journal  
Angiogenesis     Hybrid Journal   (Followers: 3, SJR: 2.177, CiteScore: 5)
Animal Cognition     Hybrid Journal   (Followers: 23, SJR: 1.389, CiteScore: 3)
Annales françaises de médecine d'urgence     Hybrid Journal   (Followers: 1, SJR: 0.192, CiteScore: 0)
Annales Henri Poincaré     Hybrid Journal   (Followers: 3, SJR: 1.097, CiteScore: 2)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4, SJR: 0.438, CiteScore: 0)
Annali dell'Universita di Ferrara     Hybrid Journal   (SJR: 0.429, CiteScore: 0)
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1, SJR: 1.197, CiteScore: 1)
Annals of Biomedical Engineering     Hybrid Journal   (Followers: 19, SJR: 1.042, CiteScore: 3)
Annals of Combinatorics     Hybrid Journal   (Followers: 4, SJR: 0.932, CiteScore: 1)
Annals of Data Science     Hybrid Journal   (Followers: 13)
Annals of Dyslexia     Hybrid Journal   (Followers: 10, SJR: 0.85, CiteScore: 2)
Annals of Finance     Hybrid Journal   (Followers: 35, SJR: 0.579, CiteScore: 1)
Annals of Forest Science     Hybrid Journal   (Followers: 7, SJR: 0.986, CiteScore: 2)
Annals of Global Analysis and Geometry     Hybrid Journal   (Followers: 1, SJR: 1.228, CiteScore: 1)
Annals of Hematology     Hybrid Journal   (Followers: 15, SJR: 1.043, CiteScore: 2)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 13, SJR: 0.413, CiteScore: 1)
Annals of Microbiology     Hybrid Journal   (Followers: 13, SJR: 0.479, CiteScore: 2)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 5, SJR: 0.687, CiteScore: 2)
Annals of Operations Research     Hybrid Journal   (Followers: 11, SJR: 0.943, CiteScore: 2)
Annals of Ophthalmology     Hybrid Journal   (Followers: 13)
Annals of PDE     Hybrid Journal  
Annals of Regional Science     Hybrid Journal   (Followers: 9, SJR: 0.614, CiteScore: 1)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annals of Solid and Structural Mechanics     Hybrid Journal   (Followers: 11, SJR: 0.239, CiteScore: 1)
Annals of Surgical Oncology     Hybrid Journal   (Followers: 15, SJR: 1.986, CiteScore: 4)
Annals of Telecommunications     Hybrid Journal   (Followers: 9, SJR: 0.223, CiteScore: 1)
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1, SJR: 1.495, CiteScore: 1)
Antonie van Leeuwenhoek     Hybrid Journal   (Followers: 5, SJR: 0.834, CiteScore: 2)
Apidologie     Hybrid Journal   (Followers: 4, SJR: 1.22, CiteScore: 3)
APOPTOSIS     Hybrid Journal   (Followers: 9, SJR: 1.424, CiteScore: 4)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 3, SJR: 0.294, CiteScore: 1)
Applications of Mathematics     Hybrid Journal   (Followers: 3, SJR: 0.602, CiteScore: 1)
Applied Biochemistry and Biotechnology     Hybrid Journal   (Followers: 44, SJR: 0.571, CiteScore: 2)
Applied Biochemistry and Microbiology     Hybrid Journal   (Followers: 19, SJR: 0.21, CiteScore: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 4, SJR: 0.49, CiteScore: 0)
Applied Composite Materials     Hybrid Journal   (Followers: 53, SJR: 0.58, CiteScore: 2)
Applied Entomology and Zoology     Partially Free   (Followers: 7, SJR: 0.422, CiteScore: 1)
Applied Geomatics     Hybrid Journal   (Followers: 3, SJR: 0.733, CiteScore: 3)
Applied Geophysics     Hybrid Journal   (Followers: 9, SJR: 0.488, CiteScore: 1)
Applied Intelligence     Hybrid Journal   (Followers: 15, SJR: 0.6, CiteScore: 2)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4, SJR: 0.319, CiteScore: 1)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 10, SJR: 0.886, CiteScore: 1)
Applied Mathematics - A J. of Chinese Universities     Hybrid Journal   (Followers: 1, SJR: 0.17, CiteScore: 0)
Applied Mathematics and Mechanics     Hybrid Journal   (Followers: 5, SJR: 0.461, CiteScore: 1)
Applied Microbiology and Biotechnology     Hybrid Journal   (Followers: 68, SJR: 1.182, CiteScore: 4)
Applied Physics A     Hybrid Journal   (Followers: 10, SJR: 0.481, CiteScore: 2)
Applied Physics B: Lasers and Optics     Hybrid Journal   (Followers: 26, SJR: 0.74, CiteScore: 2)
Applied Psychophysiology and Biofeedback     Hybrid Journal   (Followers: 8, SJR: 0.519, CiteScore: 2)
Applied Research in Quality of Life     Hybrid Journal   (Followers: 12, SJR: 0.316, CiteScore: 1)
Applied Solar Energy     Hybrid Journal   (Followers: 22, SJR: 0.225, CiteScore: 0)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 6, SJR: 0.542, CiteScore: 1)
Aquaculture Intl.     Hybrid Journal   (Followers: 26, SJR: 0.591, CiteScore: 2)
Aquarium Sciences and Conservation     Hybrid Journal   (Followers: 2)
Aquatic Ecology     Hybrid Journal   (Followers: 37, SJR: 0.656, CiteScore: 2)
Aquatic Geochemistry     Hybrid Journal   (Followers: 3, SJR: 0.591, CiteScore: 1)
Aquatic Sciences     Hybrid Journal   (Followers: 14, SJR: 1.109, CiteScore: 3)
Arabian J. for Science and Engineering     Hybrid Journal   (Followers: 5, SJR: 0.303, CiteScore: 1)
Arabian J. of Geosciences     Hybrid Journal   (Followers: 2, SJR: 0.319, CiteScore: 1)
Archaeological and Anthropological Sciences     Hybrid Journal   (Followers: 22, SJR: 1.052, CiteScore: 2)
Archaeologies     Hybrid Journal   (Followers: 13, SJR: 0.224, CiteScore: 0)
Archiv der Mathematik     Hybrid Journal   (Followers: 1, SJR: 0.725, CiteScore: 1)
Archival Science     Hybrid Journal   (Followers: 68, SJR: 0.745, CiteScore: 2)
Archive for History of Exact Sciences     Hybrid Journal   (Followers: 7, SJR: 0.186, CiteScore: 1)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 3, SJR: 0.909, CiteScore: 1)
Archive for Rational Mechanics and Analysis     Hybrid Journal   (SJR: 3.93, CiteScore: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 6, SJR: 0.79, CiteScore: 2)
Archives and Museum Informatics     Hybrid Journal   (Followers: 171, SJR: 0.101, CiteScore: 0)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 6, SJR: 1.41, CiteScore: 5)
Archives of Dermatological Research     Hybrid Journal   (Followers: 7, SJR: 1.006, CiteScore: 2)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 14, SJR: 0.773, CiteScore: 2)
Archives of Gynecology and Obstetrics     Hybrid Journal   (Followers: 18, SJR: 0.956, CiteScore: 2)
Archives of Microbiology     Hybrid Journal   (Followers: 10, SJR: 0.644, CiteScore: 2)
Archives of Orthopaedic and Trauma Surgery     Hybrid Journal   (Followers: 9, SJR: 1.146, CiteScore: 2)
Archives of Osteoporosis     Hybrid Journal   (Followers: 2, SJR: 0.71, CiteScore: 2)
Archives of Sexual Behavior     Hybrid Journal   (Followers: 11, SJR: 1.493, CiteScore: 3)
Archives of Toxicology     Hybrid Journal   (Followers: 18, SJR: 1.541, CiteScore: 5)
Archives of Virology     Hybrid Journal   (Followers: 5, SJR: 0.973, CiteScore: 2)
Archives of Women's Mental Health     Hybrid Journal   (Followers: 17, SJR: 1.274, CiteScore: 3)
Archivio di Ortopedia e Reumatologia     Hybrid Journal  
Archivum Immunologiae et Therapiae Experimentalis     Hybrid Journal   (Followers: 2, SJR: 0.946, CiteScore: 3)
ArgoSpine News & J.     Hybrid Journal  
Argumentation     Hybrid Journal   (Followers: 6, SJR: 0.349, CiteScore: 1)
Arid Ecosystems     Hybrid Journal   (Followers: 3, SJR: 0.2, CiteScore: 0)
Arkiv för Matematik     Hybrid Journal   (Followers: 1, SJR: 0.766, CiteScore: 1)
arktos : The J. of Arctic Geosciences     Hybrid Journal  
Arnold Mathematical J.     Hybrid Journal   (Followers: 1, SJR: 0.355, CiteScore: 0)
Arthropod-Plant Interactions     Hybrid Journal   (Followers: 2, SJR: 0.839, CiteScore: 2)
Arthroskopie     Hybrid Journal   (Followers: 1, SJR: 0.131, CiteScore: 0)
Artificial Intelligence and Law     Hybrid Journal   (Followers: 12, SJR: 0.937, CiteScore: 2)
Artificial Intelligence Review     Hybrid Journal   (Followers: 22, SJR: 0.833, CiteScore: 4)
Artificial Life and Robotics     Hybrid Journal   (Followers: 10, SJR: 0.226, CiteScore: 0)
Asia Europe J.     Hybrid Journal   (Followers: 4, SJR: 0.504, CiteScore: 1)
Asia Pacific Education Review     Hybrid Journal   (Followers: 12, SJR: 0.479, CiteScore: 1)
Asia Pacific J. of Management     Hybrid Journal   (Followers: 17, SJR: 1.185, CiteScore: 2)

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Similar Journals
Journal Cover
Acta Geochimica
Journal Prestige (SJR): 0.24
Citation Impact (citeScore): 1
Number of Followers: 7  
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 2096-0956 - ISSN (Online) 2365-7499
Published by Springer-Verlag Homepage  [2573 journals]
  • Chemical and boron isotopic compositions of tourmaline in the Longtoushan
           hydrothermal gold deposit, Guangxi, China: implications for gold
    • Abstract: Abstract The Longtoushan hydrothermal gold deposit is located in the southwestern region of the Dayaoshan Uplift. Tourmaline is widespread in the Longtoushan gold deposit and is mainly distributed in the rhyolite porphyry and associated cryptoexplosive breccia. The spatial distribution of tourmaline enrichment is similar to that of the gold orebody. Feldspar has been largely replaced by tourmaline in the rhyolite porphyry and cryptoexplosive breccia. Electron microprobe analysis revealed that tourmalines in the Longtoushan deposit belong mainly to the alkali group and partly to the X-vacant group; they mostly fell in the schorl-dravite series field. Two distinct sets of dominant substitutions were observed: MgFe−1 and Al□(NaR2+)−1, where R = Fe, Mg. In addition, minor substitutions include (CaMg)(NaAl)−1 and FeAl−1. The calculated δ11B value for the mineralizing fluids ranged from − 12.8 to − 9.7‰, which is typical of S-type granites, and boron-enriched fluids predominantly derived from rhyolitic melt. Part of the tourmaline from the rhyolite porphyry crystallized during the magmatic-hydrothermal stage, whereas most tourmalines from the deposit formed in the post-magmatic hydrothermal stage. The tourmalines were deposited from a relatively reduced and acidic fluid system, and the gold predominantly precipitated during the post-magmatic hydrothermal stage in the Longtoushan deposit.
      PubDate: 2019-04-01
  • Variability in distribution of major and trace elements in Lower Eocene
           siliceous sections of the Transuralian Region, Russia
    • Abstract: Abstract This paper presents lithologic and geochemical data from the sequence of the Eocene Irbit formation siliceous rocks (Transuralian Region) outcropping in a quarry in the Irbit deposit (thickness of 15 m) and in a large natural outcrop, Belaya Gorka (thickness of 13 m). The data show that both outcrops are composed of diatomites and clayey diatomites, both characterized by a certain degree of lithologic heterogeneity around their chemical, granulometric, and mineralogical compositions; microstructural features; and degree of diatom preservation. The values of indices important for the classification of siliceous rocks and determination of prospects for their industrial application—SiO2, Al2O3, Fe2O3, and clay fraction content—ranged from 66% to 77%, 7% to 14%, 3.00% to 5.60%, and 23% to 50%, respectively. In all studied lithologic varieties, element abundances of V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Ge, and Sb were two to three times higher than their respective abundances in the Earth’s crust. This is probably related to these elements’ involvement in the biological cycle and favorable conditions for transport. Rb, Cs, Ba, and Sr, as well as rare earth elements, are considered the most reliable indicators of lithologic and geochemical subdivision of a sequence of siliceous rocks, as they are associated mainly with clayey minerals. Variations in these indicators have recorded, with great probability, even short-term cycles and semi-cycles of silica sedimentation in the Transuralian Region, as well as tectonic regime and involvement of terrigenous influx.
      PubDate: 2019-04-01
  • Is seawater geochemical composition recorded in marine carbonate'
           Evidence from iron and manganese contents in Late Devonian carbonate rocks
    • Abstract: Abstract Iron and manganese are the important redox-sensitive elements in the ocean. Previous studies have established a series of paleo-depositional redox proxies based on the form and content of iron in sedimentary rocks (e.g., degree of pyritization, FeHR/FeT, Fe/Al). These proxies were developed and applied on siliciclastic-rich marine sediments. Although marine carbonate rocks are generally considered to preserve the geochemical signals of ancient seawater, neither Fe nor Mn content in marine carbonate rocks (Fecarb, Mncarb) has been independently used as a proxy to quantify environmental cues in paleo-oceans. Both Fe and Mn are insoluble in oxic conditions (Fe2O3, Fe(OH)3, MnO2), while their reduced forms (Fe2+ and Mn2+) are soluble. Therefore, oxic seawater should have low concentrations of dissolved Fe2+ and Mn2+, and accordingly carbonate rocks precipitated from oxic seawater should have low Fecarb and Mncarb, and vice versa. To evaluate whether Fecarb and Mncarb can be used to quantify oxygen fugacity in seawater, we measured Fecarb and Mncarb of Upper Devonian marine carbonate rocks collected from nine sections in South China. Fecarb of intraplatform basin samples was significantly higher than that of shelf samples, while shelf and basin samples had comparable Mncarb. The modeling result indicates that the dramatic difference in Fecarb cannot be explained by variation in oxygen fugacity between the shelf and basin seawater. Instead, both Fecarb and Mncarb appear to be more sensitive to benthic flux from sediment porewater that is enriched in Fe2+ and Mn2+. Porewater Fe2+ and Mn2+ derive from bacterial iron and manganese reduction; flux was controlled by sedimentation rate and the depth of the Fe(Mn) reduction zone in sediments, the latter of which is determined by oxygen fugacity at the water–sediment interface. Thus, high Fecarb of the basin samples might be attributed to low sedimentation rate and/or low oxygen fugacity at the seafloor. However, invariant Mncarb of the shelf and basin samples might be the consequence of complete reduction of Mn in sediments. Our study indicates that marine carbonate rocks may not necessarily record seawater composition, particularly for benthic carbonate rocks. The influence of benthic flux might cause carbonate rocks’ geochemical signals to deviate significantly from seawater values. Our study suggests that interpretation of geochemical data from carbonate rocks, including carbonate carbon isotopes, should consider the process of carbonate formation.
      PubDate: 2019-04-01
  • Geochemical distribution, fractionation, and sources of heavy metals in
           dammed-river sediments: the Longjiang River, Southern China
    • Abstract: Abstract In the present study, six sediment cores were collected from six river-dammed reservoirs to reveal the geochemical distribution of heavy metals (As, Cd, Pb, Sb, and Zn) in the Longjiang River, South China, which is highly impacted by nonferrous metal mining and smelting activities. The sediments were geochemically characterized, combining geochemical analysis, sequential extractions, and 210Pb chronology. The results indicated that the river sediments were severely polluted by heavy metals in the order of Cd > Zn ≈ Pb ≈ Sb > As. These heavy metals generally exhibited relatively low enrichment in the upstream sediments because of the limited anthropogenic impact, but their abundances drastically increased in the midstream sediments due to local smelting activities. In downstream sediments, the heavy metal concentrations (except for Cd) decreased, owing to the effect of dam interception and detrital inputs. Cadmium levels tended to increase in downstream sediments, which were attributed to the intensive discharge of Cd during the pollution event in 2012. The sedimentary records were traced back to 1985, and a significant decrease of heavy metal enrichments could be found after the year 2000, suggesting the enhancement of environmental management in this period. The statistical results indicated that local metal smelting and mining activities were the main anthropogenic contributors for the enrichment of heavy metals in the dammed-river sediments. High enrichment factor and non-residual fractions of heavy metals in local sediments may pose a direct threat to aquatic organisms. Cd presents significant danger because of its extreme enrichment and high labile fractions.
      PubDate: 2019-04-01
  • The use of hydrogeochemical analyses and multivariate statistics for the
           characterization of thermal springs in the Constantine area, Northeastern
    • Abstract: Abstract This paper deals with the results of a hydrogeochemistry study on the thermal waters of the Constantine area, Northeastern Algeria, using geochemical and statistical tools. The samples were collected in December 2016 from twelve hot springs and were analyzed for physicochemical parameters (electric conductivity, pH, total dissolved solids, temperature, Ca, Mg, Na, K, HCO3, Cl, SO4, and SiO2). The waters of the thermal springs have temperatures varying from 28 to 51 °C and electric conductivity values ranging from 853 to 5630 μS/cm. Q-mode Cluster analysis resulted in the determination of two major water types: a Ca–HCO3–SO4 type with a moderate salinity and a Na–K–Cl type with high salinity. The plot of the major ions versus the saturation indices suggested that the hydrogeochemistry of thermal groundwater is mainly controlled by dissolution/precipitation of carbonate minerals, dissolution of evaporite minerals (halite and gypsum), and ion exchange of Ca (and/or Mg) by Na. The Gibbs diagram shows that evaporation is another factor playing a minor role. Principal Component Analysis produced three significant factors which have 88.2% of total variance that illustrate the main processes controlling the chemistry of groundwaters, which are respectively: the dissolution of evaporite minerals (halite and gypsum), ion exchange, and dissolution/precipitation of carbonate minerals. The subsurface reservoir temperatures were calculated using different cation and silica geothermometers and gave temperatures ranging between 17 and 279 °C. The Na–K and Na–K-Ca geothermometers provided high temperatures (up to 279 °C), whereas, estimated geotemperatures from K/Mg geothermometers were the lowest (17–53 °C). Silica geothermometers gave the most reasonable temperature estimate of the subsurface waters overlap between 20 and 58 °C, which indicate possible mixing with cooler Mg groundwaters indicated by the Na–K–Mg plot in the immature water field and in silica and chloride mixing models. The results of stable isotope analyses (δ18O and δ2H) suggest that the origin of thermal water recharge is precipitation, which recharged from a higher altitude (600–1200 m) and infiltrated through deep faults and fractures in carbonate formations. They circulate at an estimated depth that does not exceed 2 km and are heated by a high conductive heat flow before rising to the surface through faults that acted as hydrothermal conduits. During their ascent to the surface, they are subjected to various physical and chemical changes such as cooling by conduction and change in their chemical constituents due to the mixing with cold groundwaters.
      PubDate: 2019-04-01
  • Geochronology and geochemistry of the five magmatic rocks in the Ningzhen
           region, China
    • Abstract: Abstract The Ningzhen region of China is located in the easternmost part of the middle-lower Yangtze River Cu–Fe polymetallic metallogenic belt. From west to east, it comprises five main intermediate–acidic intrusive complexes: the Qilinmen, Anjishan, Xiashu–Gaozi, Shima, and Jianbi complexes. Geochemical investigations show that these five intrusive complexes exhibit high contents of SiO2, at 64.74–73.40 wt%, Al2O3, at 14.15–17.37 wt%, and K2O + Na2O, at 6.49–8.68 wt%. The majority of the samples belong to the high-K calc-alkaline series, with a few samples plotting in the calc-alkaline and tholeiitic series. Trace element analysis shows that the samples are enriched in large ion lithophile elements (LILE) and are depleted in high field strength elements (HFSE). The chondrite-normalized rare earth element (REE) patterns are characterized by right-inclined curves, showing light rare earth element (LREE) enrichment. In addition, the (La/Yb)N ratios are high at 15.02–37.28, with an average of 29.13, and slightly negative or none Eu anomalies are present. In the (La/Yb)N–δEu diagram, the samples plot within the crust-mantle type field. Laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) zircon U–Pb dating yielded ages of 122.0 ± 1.0 Ma, 106.1 ± 0.8 Ma, 108.7 ± 1.4 Ma, 103.5 ± 1.9 Ma, and 96.8 ± 1.7 Ma for the Qilinmen, Anjishan, Xiashu–Gaozi, Shima, and Jianbi complexes, respectively. On the basis of this research and knowledge of several known metal deposits related to these complexes, we suggest that the Mesozoic large-scale diagenesis and metallogenesis in the Ningzhen region may have ceased at 100 Ma or about 95 Ma.
      PubDate: 2019-04-01
  • An experimental study on metal precipitation driven by fluid mixing:
           implications for genesis of carbonate-hosted lead–zinc ore deposits
    • Abstract: Abstract A type of carbonate-hosted lead–zinc (Pb–Zn) ore deposits, known as Mississippi Valley Type (MVT) deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping with or without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H2S, rather than HS− or S2−, dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.
      PubDate: 2019-04-01
  • Distribution and partitioning of heavy metals in large anthropogenically
           impacted river, the Pearl River, China
    • Abstract: Abstract In order to evaluate the distribution and partitioning characteristics of heavy metals in the large anthropogenically impacted Pearl River Basin, the contents of “anthropophile” elements (Cr, Ni, Cu, Zn, Cd and Pb, which are clearly influenced by human activities) were determined, and their partitioning coefficients (Kd) between water and sediments and enrichment factors (EF) were calculated for samples collected at different locations along the Pearl River main stream. The modified BCR sequential extraction procedure (proposed by the European Community Bureau of Reference in 1993), which involves the successive extraction of metals in a decreasing order of reactivity, was applied. Sediment samples from the upper, middle, and lower reaches were included in this study. The results showed that the content of most metals in water and sediment samples gradually increases from upstream to downstream, suggesting a possible input from human activities as shown by their increasing high EF, ranged from 1.4 to 3.9 for Cu, from 1.4 to 6.7 for Zn, from 2.5 to 59.1 for Cd, and from 1.7 to 8.9 for Pb, respectively. The higher partition coefficients (Kd) for Cr, Zn, and Pb (105–106) indicated that they were mainly transported in solid phase, while parts of Ni, Cu, and Cd were transported in dissolved phase as they display relatively lower Kd in the range of 104–105. According to the results of the BCR leaching, the percentage of non-residual fraction of heavy metals in the sediments showed a decreasing order of Cd > Pb > Zn > Cu > Ni > Cr, implying that Cd and Pb were more active and bioavailable compared to the other four metals, and thus would be potentially more harmful to the watershed ecosystem.
      PubDate: 2019-04-01
  • Geochemistry, mineralogy, and radioactivity of the Abu Furad Area, Central
           Eastern Desert, Egypt
    • Abstract: Abstract Abu Furad is in the Central Eastern Desert, Egypt. It comprises metasediments, metavolcanics, metagabbros, syn- to late-orogenic granites, and post-orogenic granites, in addition to numerous dykes and veins of different shapes and composition invading all the older rocks cropping out in the study area. Field, petrographic, mineralogical, and chemical investigations led to the classification of Abu Furad granites as quartz diorite, tonalite, granodiorite, and syenogranites.Major oxide and trace element data revealed that the syn- to late-orogenic granites and post-orogenic granites are peraluminous. Syn- to late-orogenic granites originated from calc-alkaline volcanic arc–related magma; while the post-orogenic granites (syenogranite) are highly fractionated, calc-alkaline granite from a within plate regime. Radiometrically, the studied quartz diorite, tonalite, and granodiorite had lower uranium and thorium contents and higher eU/eTh ratios than the syenogranites. This may indicate that the syn- to late-orogenic rocks originated from sources depleted in these elements. The average eTh/eU ratio of syenogranites was higher than that of average continental crust, suggesting that the syenogranites are relatively depleted in U. The studied altered syenogranites were strongly enriched in U and Th compared to the Earth’s crust. On the other hand, the average of eU in pegmatites is lower than the global average for uraniferous pegmatites. The most recorded accessory minerals in the altered syenogranites were thorite, fergusonite, samarskite, columbite, zircon, monazite, xenotime, apatite, fluorite, sphene, atacamite, and malachite, in addition to chromium and nickel inclusions.
      PubDate: 2019-04-01
  • Diel methane flux from a subtropical eutrophic pond in November based on
           continuous monitoring
    • Abstract: Abstract A field campaign was carried out to investigate continuous diel methane (CH4) flux from a subtropical eutrophic pond in November 2016. The diffusive methane flux of a single measurement had a range from 2.68 × 10−5 to 0.028 mmol·m−2·h−1 with an average of 0.011 ± 0.005 mmol·m−2·h−1. The diffusive methane flux of measurements from 9:00 to 10:30 and from 21:00 to 22:30 were very close to the average diffusive flux of all measurements. The bubble methane flux at different time measurements had much more variability than the diffusive methane flux. The bubble methane flux of a single measurement had a range from 0 to 0.312 mmol·m−2·h−1 with an average of 0.024 ± 0.054 mmol·m−2·h−1. For the eutrophic pond, the average bubble and diffusive CH4 flux were 0.56 ± 0.18 and 0.26 ± 0.04 mmol·m−2·day−1, respectively, and the CH4 ebullition flux accounted for 68.23% of the total flux. The maximum of the bubble CH4 flux was about 4.6 times of the minimum CH4 ebullition. The maximum of diffusive CH4 flux was ~ 1.7 times of the corresponding minimum. The diffusive methane fluxes in daytime and nighttime were almost equal. However, the bubble methane flux in daytime was 0.029 mmol·m−2·h−1, which was 1.6 times of that at night. Wind speed, the surface water temperature, and DO dominate methane effluxes from the pond, and the latter is in nature subjected to the metabolism of algae in the pond. However, key environmental factors which dominate gas flux processes vary with different weather conditions. Wind speed is unimportant when it is extremely low.
      PubDate: 2019-04-01
  • Using trace elements of magnetite to constrain the origin of the Pingchuan
           hydrothermal low-Ti magnetite deposit in the Panxi area, SW China
    • Abstract: Abstract The Pingchuan iron deposit, located in the Yanyuan region of Sichuan Province, SW China, has an ore reserve of 40 Mt with ~ 60 wt% Fe. Its genesis is still poorly understood. The Pingchuan iron deposit has a paragenetic sequence of an early Fe-oxide–Pyrite stage (I) and a late Fe-oxide–pyrrhotite stage (II). Stage I magnetite grains are generally fragmented, euhedral–subhedral, large-sized crystals accompanying with slightly postdated pyrite. Stage II magnetite grains are mostly unfragmented, anhedral, relatively small-sized grains that co-exist with pyrrhotite. Combined with micro-textural features and previously-obtained geochronological data, we consider that these two stages of iron mineralization in the Pingchuan deposit correspond to the Permian ELIP magmatism and Cenozoic fault activity event. Both the Stage I and II magnetites are characterized with overall lower contents of trace elements (including Cr, Ti, V, and Ni) than the ELIP magmatic magnetite, which suggests a hydrothermal origin for them. “Skarn-like” enrichment in Sn, Mn, and Zn in the Stage I magnetite grains indicate significant material contributions from carbonate wall-rocks due to water–rock interaction in ore-forming processes. Stage II magnetite grains contain higher Mn concentrations than Stage I magnetite grains, which possibly implies more contribution from carbonate rocks. In multiple-element diagrams, the Stage I magnetite shows systematic similarities to Kiruna-type magnetite rather than those from other types of deposits. Combined with geological features and previous studies on oxygen isotopes, we conclude that hydrothermal fluids have played a key role in the generation of the Pingchuan low-Ti iron deposit.
      PubDate: 2019-03-22
  • Altitude-dependent distribution of 137 Cs in the environment: a case study
           of Aragats massif, Armenia
    • Abstract: Abstract This paper considers the distribution of technogenic 137Cs and naturally occurring radionuclides: 238U, 232Th and 40К concentrations in soils and 137Cs in atmospheric dry depositions by altitudinal belts of the Aragats mountain massif, Republic of Armenia. Undisturbed soil samples were collected at altitudes from 1000 to 3200 m. For the determination of geochemical variability, two soil sampling campaigns were undertaken. Atmospheric dry depositions were sampled from five stations at 1100–3200 m collected onto organic fiber filters between June and December 2016. 137Cs activity was measured using a high-purity Germanium detector coupled to a multichannel analyzer (Canberra). Results indicated that specific activity of 137Cs in soils at 1000 m is 495–528 Bq m−2, and at 3200 m is 10,500–11,470 Bq m−2. No correlation observed for 137Cs versus naturally occurring radionuclides, which varies in distribution by altitude. Specific activities of 137Cs in dry atmospheric depositions varies from 1.06 at 846 m to 2.37 Bq m−2 per quarter at 3200 m and increases as the altitude increases. Activities of 137Cs in soil and dry atmospheric deposition correlated significantly, and 137Cs activity in soils and atmospheric dry depositions decrease as the absolute altitude decreases. The 50-year effective dose from exposure to 137Cs fallout varies with altitude from 0.007 to 1.42 mSv.
      PubDate: 2019-03-19
  • Correction to: The enhanced element enrichment in the supercritical states
           of granite–pegmatite systems
    • Abstract: In the original publication, there are some missing data in Table 1 and incorrect data in Table 2.
      PubDate: 2019-03-16
  • Geochemistry and sediment in the main stream of the Ca River basin,
           Vietnam: weathering process, solute-discharge relationships, and reservoir
    • Abstract: Abstract In this study, we investigated the chemical composition of dissolved solids in the Ca River basin, North-Central Vietnam. Water samples were collected from August 2017 to July 2018 at three hydrological stations located in the main stream of the Ca River. Carbonate weathering was found as the dominant process controlling the water chemistry in that area. The average concentrations of dissolved solids generally decreased from upstream to downstream, resulting in low concentrations of the major ions in the downstream basin. Variations in the concentrations of major chemical ions and suspended solids at discharge were also investigated. Major chemical weathering products were found to behave chemostatically with increasing discharges upstream. However, dilution behaviors of solutes were shown in both midstream and downstream. Primary evidence shows that water storage in reservoirs impacts a variety of suspended solids and dissolved solids in the Ca River.
      PubDate: 2019-03-16
  • Groundwater quality assessment using multivariate analysis, geostatistical
           modeling, and water quality index (WQI): a case of study in the
           Boumerzoug-El Khroub valley of Northeast Algeria
    • Abstract: Abstract In this study, the analytical data set of 26 groundwater samples from the alluvial aquifer of Boumerzoug-El khroub valley has been processed simultaneously with Multivariate analysis, geostatistical modeling, WQI, and geochemical modeling. Cluster analysis identified three main water types based on the major ion contents, where mineralization increased from group 1 to group 3. These groups were confirmed by FA/PCA, which demonstrated that groundwater quality is influenced by geochemical processes (water–rock interaction) and human practice (irrigation). The exponential semivariogram model fitted best for all hydrochemical parameters values and WQI. Groundwater chemistry has a strong spatial structure for Mg, Na, Cl, and NO3, and a moderate spatial structure for EC, Ca, K, HCO3, and SO4. Water quality maps generated using ordinary Kriging are consistent with the HCA and PCA results. All water groups are supersaturated with respect to carbonate minerals, and dissolution of kaolinite and Ca-smectite is one of the processes responsible for hydrochemical evolution in the area.
      PubDate: 2019-03-13
  • The occurrences and geochemical characteristics of thorium in iron ore in
           the Bayan Obo deposit, Northern China
    • Abstract: Abstract The Bayan Obo deposit in northern China is an ultra-large Fe–REE–Nb deposit. The occurrences, and geochemical characteristics of thorium in iron ores from the Bayan Obo Main Ore Body were examined using chemical analysis, field emission scanning electron microscopy, energy dispersive spectrometer, and automatic mineral analysis software. Results identified that 91.69% of ThO2 in the combined samples was mainly distributed in rare earth minerals (bastnaesite, huanghoite, monazite; 56.43% abundance in the samples), iron minerals (magnetite, hematite, pyrite; 20.97%), niobium minerals (aeschynite; 14.29%), and gangue minerals (aegirine, riebeckite, mica, dolomite, apatite, fluorite; 4.22%). An unidentified portion (4.09%) of ThO2 may occur in other niobium minerals (niobite, ilmenorutile, pyrochlore). Only a few independent minerals of thorium occur in the iron ore samples. Thorium mainly occurs in rare earth minerals in the form of isomorphic substitution. Analyses of the geochemical characteristics of the major elements indicate that thorium mineralization in the Main Ore Body was related to alkali metasomatism, which provided source material and favorable porosity for hydrothermal mineralization. Trace elements such as Sc, Nb, Zr, and Ta have higher correlation coefficients with thorium, which resulted from being related to the relevant minerals formed during thorium mineralization. In addition, correlation analysis of ThO2 and TFe, and REO and TFe in the six types of iron ore samples showed that ThO2 did not always account for the highest distribution rate in rare earth minerals, and the main occurrence minerals of ThO2 were closely related to iron ore types.
      PubDate: 2019-03-13
  • Rare-earth and trace elements and hydrogen and oxygen isotopic
           compositions of Cretaceous kaolinitic sediments from the Lower Benue
           Trough, Nigeria: provenance and paleoclimatic significance
    • Abstract: Abstract This study evaluated the Cretaceous (Campanian–Maastrichtian) kaolinitic sediments of the Ajali/Mamu and Enugu/Nkporo Formations from the Lower Benue Trough of Nigeria. A combined method of inductively coupled plasma–mass spectrometry and isotope ratio mass spectrometry was used to investigate trace and rare-earth element geochemistry and hydrogen and oxygen isotopic compositions. These data were then used to infer the sediments’ provenance and paleoclimatic conditions during their deposition. The sediments contained low concentrations of most trace elements, with the exceptions of Zr (651–1352 ppm), Ba (56–157 ppm), V (38–90 ppm), and Sr (15.1–59.6 ppm). Average values of Co and Ni were 1.5 and 0.7 ppm, respectively. Trace and rare earth element values were lower than corresponding values for upper continental crust and Post-Archean Australian Shale, with the exception of Zr. The samples showed only slight light rare-earth enrichment and nearly flat heavy rare-earth depletion patterns, with negative Eu and Tm anomalies, typical of felsic sources. Geochemical parameters such as La/Sc, Th/Sc, and Th/Co ratios support that the kaolinitic sediments were derived from a felsic rock source, likely deposited in an oxic environment. 18O values ranged from + 15.4 to + 21.2‰ for the investigated samples, consistent with a residual material derived from chemical weathering of felsic rock and redeposited in a sedimentary basin (typical values of + 19 to + 21.2‰). While in the basin, the sediments experienced extended interactions with meteoric water enriched in δD and δ16O. However, the variation in δD and δ16O values for the investigated samples is attributed to the high temperature of formation (54–91 °C). The δD and δ18O values suggest that the sediments, although obtained from different localities within the Lower Benue Trough, formed under similar hot, tropical climatic conditions.
      PubDate: 2019-03-11
  • A review of geoanalytical databases
    • Abstract: Abstract Geoanalytical data provide fundamental information according to which the Earth’s resources can be known and exploited to support human life and development. Large amounts of manpower and material and financial resources have been invested to acquire a wealth of geoanalytical data over the past 40 years. However, these data are usually managed by individual researchers and are preserved in an ad hoc manner without metadata that provide the necessary context for interpretation and data integration requirements. In this scenario, fewer data, except for published data, can be reutilized by geological researchers. Many geoanalytical databases have been constructed to collect existing data and to facilitate their use. These databases are useful tools for preserving, managing, and sharing data for geological research, and provide various data repositories to support geological studies. Since these databases are dispersed and diverse, it is difficult for researchers to make full use of them. This contribution provides an introduction on available geoanalytical databases. The database content can be made accessible to researchers, the ways in which this can be done, and the functionalities that can be used are illustrated in detail. Moreover, constraints that have limited the reutilization of geoanalytical data and creation of more advanced geoanalytical databases are discussed.
      PubDate: 2019-03-08
  • Isotherm and kinetic studies on the adsorption of humic acid molecular
           size fractions onto clay minerals
    • Abstract: Abstract Humic acid (HA) can adsorb onto mineral surfaces, modifying the physicochemical properties of the mineral. Therefore, understanding the sorption behavior of HA onto mineral surfaces is of particular interest, since the fate and transport of many organic and inorganic contaminants are highly correlated to HA adsorbed onto clay surfaces. Due to the extreme heterogeneity of HA, the extracted IHSS Leonardite humic acid (LHA) used in this work was fractionated using an ultrafiltration technique (UF) into different molecular size fractions (Fr1, > 0.2 µm; Fr2, 0.2 µm–300,000 daltons; Fr3, 300,000–50,000 daltons; Fr4, 50,000–10,000 daltons; Fr5, 10,000–1000 daltons). Equilibrium and the kinetics of LHA and fraction adsorption onto kaolinite and montmorillonite were investigated. The results demonstrated that the maximum adsorption capacity of LHA, Fr1, Fr2, Fr3, Fr4, and Fr5 was 5.99, 13.69, 10.29, 7.02, 5.98, and 5.09 on kaolinite while it was 8.29, 22.62, 13.17, 8.91, 8.62, and 5.69 on montmorillonite, respectively. The adsorption equilibrium data showed that the adsorption behavior of LHA and its fractions could be described more practically by the Langmuir model than the Freundlich model. The rate of humic acid fraction adsorption onto clays increased with decreasing molecular size fraction and increasing carboxylic group content. Pseudo-first- and second-order models were used to assess the kinetic data and the rate constants. The results explained that LHA and its fractions adsorption on clay minerals conformed more to pseudo-second-order.
      PubDate: 2019-03-08
  • An experimental study on dynamic coupling process of alkaline feldspar
           dissolution and secondary mineral precipitation
    • Abstract: Abstract In order to clarify the dynamic process of feldspar dissolution–precipitation and explore the formation mechanism of secondary porosity, six batch reactor experiments were conducted at 200 °C and pH = 7 measured at room temperature. Temporal evolution of fluid chemistry was analyzed with an inductively coupled plasma optical emission spectrometer (ICP-OES). Solid reaction products were retrieved from six batch experiments terminated after 36, 180, 276, 415, 766 and 1008 h. Scanning electron microscopy (SEM) revealed dissolution features and significant secondary mineral adhered on the feldspar surface. The process of feldspar dissolution–precipitation proceeded slowly and full equilibrium was not achieved after 1008 h. Saturation indices suggested that the albite and K-feldspar dissolution occurred throughout the experiments. The average dissolution rates for albite and K-feldspar were 2.28 × 10−10 and 8.51 × 10−11 mol m−2 s−1, respectively. Based on the experimental data, the reaction process of alkaline feldspar was simulated and the secondary porosity had increased 0.3% after the experiment.
      PubDate: 2019-03-06
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