Publisher: Springer-Verlag (Total: 2570 journals)

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Showing 1 - 200 of 2570 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: 9, SJR: 0.752, CiteScore: 3)
Abdominal Radiology     Hybrid Journal   (Followers: 21, 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: 31, 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: 33, 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: 3, 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: 8, 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: 3, SJR: 0.376, CiteScore: 1)
Acta Neuropathologica     Hybrid Journal   (Followers: 5, 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   (Followers: 1)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9, 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: 10)
Administration and Policy in Mental Health and Mental Health Services Research     Partially Free   (Followers: 21, SJR: 1.005, CiteScore: 2)
Adolescent Research Review     Hybrid Journal   (Followers: 2)
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: 23, 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: 8)
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: 20, SJR: 0.862, CiteScore: 1)
Afrika Matematika     Hybrid Journal   (Followers: 3, 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: 19, SJR: 1.864, CiteScore: 6)
AI & Society     Hybrid Journal   (Followers: 9, SJR: 0.227, CiteScore: 1)
AIDS and Behavior     Hybrid Journal   (Followers: 17, SJR: 1.792, CiteScore: 3)
Air Quality, Atmosphere & Health     Hybrid Journal   (Followers: 5, 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: 30, 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: 19, SJR: 0.46, CiteScore: 1)
American J. of Dance Therapy     Hybrid Journal   (Followers: 7, 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: 11, 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: 11, 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: 14, SJR: 0.413, CiteScore: 1)
Annals of Microbiology     Hybrid Journal   (Followers: 13, SJR: 0.479, CiteScore: 2)
Annals of Nuclear Medicine     Hybrid Journal   (Followers: 4, SJR: 0.687, CiteScore: 2)
Annals of Operations Research     Hybrid Journal   (Followers: 11, SJR: 0.943, CiteScore: 2)
Annals of Ophthalmology     Hybrid Journal   (Followers: 14)
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: 17, 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: 5, 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: 43, 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: 10, 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: 38, 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: 70, 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: 176, 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: 19, 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: 10, 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: 25, 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
Aquatic Geochemistry
Journal Prestige (SJR): 0.591
Citation Impact (citeScore): 1
Number of Followers: 3  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1573-1421 - ISSN (Online) 1380-6165
Published by Springer-Verlag Homepage  [2570 journals]
  • Ecosystem-Scale Modeling and Field Observations of Sulfate and
           Methylmercury Distributions in the Florida Everglades: Responses to
           Reductions in Sulfate Loading
    • Abstract: Abstract The Florida Everglades has one of the most severe methylmercury (MeHg) contamination issues in the USA, resulting from factors including high rates of atmospheric mercury (Hg) deposition and sulfate inputs from agricultural lands. Sulfate loading stimulates microbial sulfate reduction and production of toxic and bioaccumulative MeHg. Controls on regional Hg emissions have been successful in reducing Hg deposition and MeHg production in wetlands in other areas, but this has not been the case for the Everglades as the Hg deposited here appears to come from unknown global sources of emissions. We posit that reductions in sulfate loading to the Florida Everglades can be an effective alternative approach used to reduce MeHg production. This study tested this hypothesis (1) by evaluating temporal trends in MeHg concentrations in response to a reduction in sulfate loading at a site in central Water Conservation Area (WCA) 3 and (2) using ecosystem-scale models to predict the effects of reductions in sulfate loading on sulfate concentrations in surface water and MeHg Risk. At the WCA site, we report a decline in sulfate concentrations (from about 9 mg/L in the late 1990s to levels of < 1 mg/L by 2001) due to changes in water delivery as part of Everglades restoration. Concurrent with the decline in sulfate, declines in MeHg concentrations in surface water and fish and wading bird tissues were observed at this site. These results suggest the efficacy of reducing MeHg production and bioaccumulation in the ecosystem through a reduction in sulfate loading. A previously developed model was used to predict the effects of reductions in sulfate loading (97%, 33%, and 10% reduction scenarios) on sulfate concentrations in surface water and MeHg Risk in the Everglades. The model identified areas of the ecosystem where MeHg Risk is most sensitive to the reductions in sulfate loading. Results show that reductions of > 33% in sulfate loading will significantly benefit the Everglades by reducing MeHg Risk.
      PubDate: 2020-02-15
       
  • Incorporation of Rare Earths and Yttrium in Calcite: A Critical
           Re-evaluation
    • Abstract: Abstract The reported partition coefficients of REE with calcite are reviewed and critically discussed. In some of the reported experimental sets, REE concentrations are found to be supersaturated with respect to individual REE2(CO3)3 but never to REE(OH)3. Although the solutions are unsaturated with respect to individual REY carbonates, REY including Y are incorporated in calcite surfaces, where they are overgrown by calcite. Charge balances may be obtained by building {REY–Na-(CO3)2}n or by exchange of 2Ca2+ against REY3+ + blank space calcite lattice. These surface compounds may either be homogeneously distributed or clustered. Both the size and frequency of clusters increase with [REY]/[Ca] or [ΣREY3+]/[Ca2+] in solution. If these surface precipitates are removed into solutions saturated with respect to ΣREE2(CO3)3, they start growing in the aqueous phase. In this case, the apparent DREY and kREY values decrease with increasing REY concentrations in solution. In previous studies, only the individual distribution coefficients are reported not considering that the entirety of REY determines their behavior in partitioning. Given enough time, these surface clusters equilibrate with the aqueous phase before being overgrown by calcite. In the double logarithmic plots of {REY}/{Ca} versus [REY]/[Ca] or [REY3+]/[Ca2+], two relationships evolve characterizing the REY distribution in marine calcite and experimental calcites grown in Mg2+-free solutions. The double logarithmic plots of partition coefficients of REYi3+ in calcite grown from seawater show a slope exceeding unity, whereas those from fluids without Mg2+ depict slopes less than unity being both in contrast to the Henderson–Kracek rule.
      PubDate: 2020-02-12
       
  • Editorial
    • PubDate: 2020-02-08
       
  • Characterizing Soil Dissolved Organic Matter in Typical Soils from China
           Using Fluorescence EEM–PARAFAC and UV–Visible Absorption
    • Abstract: Abstract Dissolved organic matter (DOM) strongly participates in a variety of critical environmental and ecological processes and has a large impact on environmental quality. In this study, ultraviolet–visible absorbance spectroscopy and excitation–emission matrices of fluorescence spectroscopy in combination with parallel factor analysis (EEMs–PARAFAC) were applied to characterize a total of 92 DOM samples extracted from four typical soil types under three different land-use regimes across China. DOC concentrations ranged from 6.52 ± 1.09 to 25.62 ± 4.83 mg L−1 and were generally higher in red soil from Guangdong and Guangxi, especially in paddy soil. Three fluorescence components were identified in soil DOM by EEMs–PARAFAC, including high molecular weight UVA humic-like substances (C1), low molecular weight autochthonous humic-like substances (C2), and protein-like substances (C3). DOM from black soil in Heilongjiang, purple soil from Sichuan, and red soil from Zhejiang had more humic-like substances, whereas DOM from yellow soil in Guizhou and red soil from Guangdong and Guangxi had lower degree of aromaticity and higher proportion of microbial-derived protein-like components (C3). Moreover, DOM from paddy soil tended to be more of protein-like components (C3) than that from other land uses and DOM from dryland soil generally had more autochthonous humic-like substances (C2). Our results demonstrated that soil DOM characteristics both varied significantly by soil type and land use, and EEMs–PARAFAC could be a useful approach to characterize the components and sources of heterogeneous DOM in soils.
      PubDate: 2020-01-02
       
  • Mineral Magnetic and Geochemical Mapping of the Wular Lake Sediments,
           Kashmir Valley, NW Himalaya
    • Abstract: Abstract This study presents major element geochemistry, mineral magnetism and textural analysis of lake-bottom sediments collected from the Wular Lake located in the Kashmir Valley (northwest Himalaya). Connected to the Jhelum River, Wular Lake basin occupies ~ 75% watershed area of the valley, covering ~ 10,196 km2, and makes it the major depo-centre for Kashmir Valley. The sediments represent dominant silt fraction with TiO2, MgO, Fe2O3 and MnO enrichment; and depletion of Na2O and P2O5 with reference to upper continental crust. The average CIA (64.17%) reflects moderate chemical weathering of the catchment source rocks. The mineral magnetic mapping identified distinct domains of restricted/reducing and well-ventilated/oxic conditions, illustrating spatial environmental variability within the lake-bottom environments. The geochemical and mineral magnetic mapping therefore provides a baseline reference for emerging climate and anthropogenic changes being experienced in the Kashmir Valley.
      PubDate: 2019-12-13
       
  • Geochemical Behavior of REE in Stream Water and Sediments in the
           Gold-Bearing Lom Basin, Cameroon: Implications for Provenance and
           Depositional Environment
    • Abstract: Abstract Stream water and associated bottom sediments were sampled within the Lom Basin, and their rare earth element (REE) concentrations have been used to decipher their provenance and environment of deposition. Stream waters in the lower Lom Basin have variable Post Archean Australian Shale-normalized REE concentrations (0.24–4978 ng/l), positive Ce anomalies (Ce/Ce* ranges from 1.08 to 8.03), a general positive Eu anomaly (Eu/Eu* varies from 0.9 to 15.2, average = 4.9) and are slightly enriched in the light rare earth elements (LREE/HREE varies from 1.7 to 10.3). Similarly, the sediments are slightly depleted in heavy rare earth elements (HREE), have a predominant negative Ce anomaly, but show a ubiquitous positive Eu anomaly. The dissolved REE content is controlled by the near-neutral pH of the stream water and adsorption onto Fe and Mn oxyhydroxides. The variable LREE/HREE ratios and Eu anomalies observed in the sediments indicate that these sediments are sourced mainly from felsic rocks with little mafic input. Moreover, Ce anomalies and redox-sensitive trace elemental ratios of Ni/Co, V/(V + Ni), V/Cr, Cu/Zn and V/Ni revealed the sediments were deposited under oxic to reducing conditions. Variations in the concentration of REE in the stream water and sediment indicate that Fe and Mn oxyhydroxides are important sinks for the HREE. The newly generated data will guide future studies and environmental policy makers.
      PubDate: 2019-12-13
       
  • Geochemistry of the Lake Chad Tributaries Under Strongly Varying
           Hydro-climatic Conditions
    • Abstract: Abstract The Lake Chad Basin (LCB) is one of the main endorheic basins in the world and has undergone large-level and surface variations during the last decades, particularly during the Sahelian dry period in the 1970s and the 1980s. The Chari–Logone River system covers 25% of the LCB but accounts for up to 82% of the Lake Chad water supply. The aim of this study is to investigate the dissolved phase transported by the Chari–Logone system, in order (1) to elucidate the origin and the behavior of major elements and the weathering processes in the watershed; (2) to estimate the total dissolved flux, its variability over the last decades and the driving factors. To do so, samples were collected monthly between January 2013 and November 2016 at three representative sites of the basin: in the Chari River in “Chagoua,” in the Logone River in “Ngueli” just before the confluence of both rivers, and at a downstream site in “Douguia,” 30 km after the confluence. Concentrations in major elements displayed significant seasonal variations in the Chari and Logone waters. At the seasonal time scale, the comparison between the concentrations of chemical elements and the flow rates showed a hysteresis loop. This hysteresis behavior corresponds to a variable contribution over time of two water bodies, fast surface water, and slow groundwater, the latter carrying higher concentrations and Ca/Na ratio, which may result from the contribution of pedogenic carbonate weathering to the dominant signature of silicate weathering. At the annual time scale, similar average concentrations are observed in the Chari and Logone Rivers, despite contrasted annual runoff. In addition, an interannual stability of ionic concentrations was observed in the Chari–Logone River during the flood regime, both during the years covered by our monitoring (2013–2016) and during the pre-drought period (1969, 1972 and 1973). This situation corresponds to a chemostatic behavior, where the annual river discharge is the main factor controlling the interannual variation of chemical fluxes.
      PubDate: 2019-11-29
       
  • The Effect of Bacterial Sulfate Reduction Inhibition on the Production and
           Stable Isotopic Composition of Methane in Hypersaline Environments
    • Abstract: Abstract The aim of this research was to investigate the competition between methanogens and sulfate-reducing bacteria in hypersaline environments. Samples of photosynthetic microbial mats, both soft mats (salinities of 55–126 ppt) and gypsum-hosted endoevaporite mats (salinities of 77–320 ppt), were obtained from hypersaline environments in California, USA, Mexico and Chile. Methane production was determined from the increase in headspace methane concentration within incubation vials containing mat samples. At the end of the incubation period, the δ13C values of produced methane were measured. Soft microbial mat vials containing molybdate, a specific inhibitor of bacterial sulfate reduction, exhibited dramatically higher methane production rates and higher (enriched in 13C) methane δ13C values than the controls. This suggests that the inhibition of sulfate reduction allowed the methanogens at these sites to use the competitive substrates (H2 and/or acetate) made available. Further, the higher δ13C values of the produced methane suggest that substrates (both competitive and non-competitive) were used to near completion. At the endoevaporite sites, which have much higher salinities than the soft mat sites, methane production was not significantly different and the methane δ13C values either remained the same or decreased (depleted in 13C) with added molybdate. We suggest that substrate availability increased enough to allow for somewhat greater isotopic fractionation resulting in the lower methane δ13C values that were observed, but not enough to significantly increase measured production rates. Where no changes in either methane production rates or δ13C values occurred, we hypothesize that salinity itself was inhibiting sulfate reduction and thus controlling microbe populations and rates of metabolism.
      PubDate: 2019-11-19
       
  • Kinetics of Thiocyanate Formation by Reaction of Cyanide and Its Iron
           Complexes with Thiosulfate
    • Abstract: Abstract Reactions between cyanide and compounds, which contain S–S bonds, in aqueous media result in formation of thiocyanate. In this work, we studied the kinetics of reactions of thiosulfate with free cyanide and its complexes under environmental conditions. Rates of reactions between cyanide species and thiosulfate decrease in the following order: CN− > HCN > [Fe(CN)6]3− > [Fe(CN)6]4−. However, at neutral and slightly acidic pH range, reaction of thiosulfate with iron-cyanide complexes outcompetes its reaction with free cyanide, which exists in equilibrium with complexed cyanide. At environmentally relevant conditions, the characteristic time of reaction between free cyanide and thiosulfate was found to be tens of thousands of years, while for iron-cyanide complexes it was found to be hundreds to millions of years. Examples of application of kinetic parameters for calculation of rates of cyanide consumption in industrial (coke oven wastewater) and non-polluted natural aquatic system (Delaware Great Marsh) are provided.
      PubDate: 2019-11-07
       
  • The Stability of Fe-Isotope Signatures During Low Salinity Mixing in
           Subarctic Estuaries
    • Abstract: Abstract We have studied iron (Fe)-isotope signals in particles (> 0.22 µm) and the dissolved phase (< 0.22 µm) in two subarctic, boreal rivers, their estuaries and the adjacent sea in northern Sweden. Both rivers, the Råne and the Kalix, are enriched in Fe and organic carbon (up to 29 µmol/L and up to 730 µmol/L, respectively). Observed changes in the particulate and dissolved phase during spring flood in May suggest different sources of Fe to the rivers during different seasons. While particles show a positive Fe-isotope signal during winter, during spring flood, the values are negative. Increased discharge due to snowmelt in the boreal region is most times accompanied by flushing of the organic-rich sub-surface layers. These upper podzol soil layers have been shown to be a source for Fe-organic carbon aggregates with a negative Fe-isotope signal. During winter, the rivers are mostly fed by deep groundwater, where Fe occurs as Fe(oxy)hydroxides, with a positive Fe-isotope signal. Flocculation during initial estuarine mixing does not change the Fe-isotope compositions of the two phases. Data indicate that the two groups of Fe aggregates flocculate diversely in the estuaries due to differences in their surface structure. Within the open sea, the particulate phase showed heavier δ56Fe values than in the estuaries. Our data indicate the flocculation of the negative Fe-isotope signal in a low salinity environment, due to changes in the ionic strength and further the increase of pH.
      PubDate: 2019-11-06
       
  • An Integrated Novel Approach to Understand the Process of Groundwater
           Recharge in Mountain and Riparian Zone Aquifer System of Tamil Nadu, India
           
    • Abstract: Abstract The nature of groundwater recharge along the mountain front (MF) and riparian zone (RZ) was discerned by multiple tools involving rain/water level relationship, geophysical of subsurface, seasonal hydrochemistry and environmental isotopic signatures. The proposed study has been carried out in Courtallam Hills, the north-western part of Tirunelveli District, South India. The study area is a hilly terrain with narrow valleys endowed with steep slopes. The relationship between water-level fluctuation and precipitation were evaluated by observing daily water level in 8-h interval at three piezometer zones and regular rainfall data. It was inferred that the RZ played a role in storage zone and gets recharged from mountain block (MB) and lateral flow. The seasonal geochemistry of the groundwater was studied to determine the sources of recharge in MF and RZ. Geostatistical treatment of factor analysis revealed that weathering was the dominant recharge process along the foothill. The geophysical studies reveal good quality of groundwater observed in the northern part along with low conductance and high resistivity. The increased level of groundwater conductivity and lower resistivity was noted in southern part of the study area due to the irrigation activities. The isotopic tracers range from − 2.5 to − 12.6‰ for δ18O and from − 91.2 to − 15.5‰ for δ2H. Moreover, the groundwater recharge was evaluated by source of rainfall moisture. High-altitude recharge from MB along the MF was clearly indicated by depleted isotopic content of the water samples. It was also supported by hydrogeochemical and statistical evidences, showing that rainfall over both MB and MF zones provided the recharge to foothill aquifers, while the RZ zone was mainly recharged by local precipitation with less contribution from regional flows.
      PubDate: 2019-10-11
       
  • Colloidal Organic Matter and Metal(loid)s in Coastal Waters (Gulf of
           Trieste, Northern Adriatic Sea)
    • Abstract: Abstract Large volumes of seawater were sampled in the Gulf of Trieste (northern Adriatic Sea) in order to study the interactions between colloidal organic matter (COM) and metal(loid)s (Me) in coastal waters. COM (> 5 kDa) was isolated by ultrafiltration and characterized using 1H NMR spectroscopy and elemental Corg. and Ntot. analyses. COM in the gulf represents about one quarter of the dissolved organic carbon (DOC), and according to 1H NMR analysis, it is composed of polysaccharides (30–45%), lipids (30–55%), proteins and carboxyl-rich alicyclic molecules (CRAM) (15–20%), and humics (< 1%). An accumulation of COM was observed in the late spring–early summer. The polysaccharide and lipid fractions increased up to twofold and the protein fraction decreased, reflected in a higher Corg./Ntot. (28, molar) ratio. Higher concentrations of humics were observed due to local freshwater discharges in spring. COM from the Isonzo/Soča River differed from the marine COM exhibiting higher protein/CRAM and higher humic contents. COM from the Isonzo/Soča mouth at salinities 16–33 was compositionally similar to marine COM. Analysis of Me, performed by ICP-MS and CVAFS (Hg), showed that Hg (nearly 100%), Cu (20%), Cr (10%), and Se (10%) have the highest Me affinity to colloids. Similar to COM, Hg and Cu rapidly increased till summer due to their sequestration in accumulated COM (transfer to particulate phase). The observed Me/Corg. ratios (Co, Cd, Hg < U, Cr, Ni, Mn < As, Zn, Cu, V < Se, Al, Fe) differ somewhat from those of the Irving–Williams series and can be explained by the composition of COM and variable background concentrations of studied Me in the northern Adriatic. Data from the salinity gradient in the metal-contaminated (especially Hg, Pb, Zn) Isonzo/Soča mouth showed flocculation of Al and Ba and desorption of V, Co, As, Se, Cs, U, and Hg, from the riverine particles with increasing ionic strength, while Fe, Mn, Cu, Cr, Ni, Zn, Cd, and Pb did not correlate with salinity.
      PubDate: 2019-10-03
       
  • The Sources of Organic Matter in Seagrass Sediments and Their Contribution
           to Carbon Stocks in the Spermonde Islands, Indonesia
    • Abstract: Abstract Seagrass ecosystems have a potential role in climate change mitigation due to their ability to store high amount of carbon, particularly in the sediment. Studying the factors and mechanisms responsible for this storing capacity is essential to understand seagrass carbon sink function. Therefore, in this study, we identified the sources of organic carbon (Corg) in seagrass sediments and the implication to Corg stocks from four islands in the Spermonde Islands that located at different zones. We used the Bayesian stable isotope mixing model to estimate the proportional contribution of different sources to sediment carbon. Seagrass meadows that located in adjacent to high anthropogenic activities (deforestation and aquacultures) with direct exposure to wave actions, such as on the Bauluang Island, accumulated organic carbon that derived from multiple sources, where phytoplankton contributed the highest, while on the other three islands that are relatively protected from wave actions, the highest contribution (~ 75%) was from autochthonous production (seagrass-derived). Sediment Corg stocks vary spatially, ranging from 11.9 to 32.1 Mg C ha−1 (based on the obtained depth of 20–55 cm), or 40.5 to 83.5 Mg C ha−1 if extrapolated to 1 m depth. The variability of sediment properties and Corg stocks in this study is not solely determined by the geographical differences (inshore, nearshore and offshore islands), but also influenced by other local factors such as hydrodynamics that control the distribution of carbon sources, anthropogenic pressures and species composition. These factors should be taken into account when developing coastal management strategies, as efforts are being undertaken to include coastal ecosystems (including seagrass ecosystems) on the National Green House Gasses Reduction Strategy.
      PubDate: 2019-09-21
       
  • Tufa Deposition Dynamics in a Freshwater Karstic Stream Influenced by Warm
           Springs
    • Abstract: Abstract Sweet Springs Creek, located in the Valley and Ridge Province of the Appalachian Mountains in southeastern West Virginia and southwestern Virginia, USA, contains major fluvial tufa formations at the sites of localized fractures and faults. Sweet Springs Creek receives input from higher-temperature thermal springs of lower pH and higher sulfate concentration that differ significantly in chemical composition due to differences in the underlying geology. In this study, theoretical rates of tufa accumulation were compared with those measured on travertine tiles left in situ for 30 days during periods of high and low stream flow above and below the sites of major fluvial tufa formations. Consistent with the chemistry of the spring waters, observed and predicted tufa accumulation rates in the stream were low compared to others reported worldwide. Tufa formation rate estimates were consistently higher during seasonal conditions of low flow, warm temperatures, and higher pH that occurred in late summer, but net annual accumulation may still be zero or less due to formation erosion during periodic flooding events. Computer tomography analysis determined that the natural porosity of travertine tiles results in a total surface area 32% greater than that calculated based solely on tile dimensions, which may overestimate initial tufa accumulation rates in situ. Measured rates of carbonate deposition on travertine tiles were 1.6–82 × lower than rates predicted based on theoretical models, consistent with the hypothesis of rate reduction due to variable diffusional boundary layer limitations and variability in stream hydrology. The generation of loose, platy, and unconsolidated precipitate on tiles under geochemical conditions predicted to be the greatest for optimal tufa formation suggested that the precipitation of particulate calcite in the stream system may predominantly result in the formation of unconsolidated marl deposits.
      PubDate: 2019-08-19
       
  • Multicomponent Versus Classical Geothermometry: Applicability of Both
           Geothermometers in a Medium-Enthalpy Geothermal System in India
    • Abstract: Abstract The Manuguru geothermal area, located in the Khammam district of Telangana state, India, is one of the least explored medium-enthalpy geothermal systems in India. In this study, subsurface reservoir temperature was estimated by applying various methodologies such as chemical geothermometry, multicomponent geothermometry and mixing models. Chemical geothermometers provided wide range in temperature estimation, and most of them (Na–K, Na–K–Ca, Mg-corrected Na–K–Ca) were found to be unsuitable for predicting reservoir temperature due to the absence of attainment of equilibrium between suitable mineral pairs. The temperature range estimated from the quartz geothermometers varied from 72 to 120 °C which matched closely with values obtained from K–Mg geothermometers. To overcome this problem and to better constrain the reservoir temperature, multicomponent solute geothermometry modelling was carried out by applying the GeoT computer code. Fluid reconstruction was done after taking into account both the degassing and mixing phenomena. GeoT modelling of the reconstructed fluid provided excellent clustering of the minerals. From the GeoT modelling study, it was found that minerals like quartz, chalcedony, calcite, etc., attained simultaneous equilibrium with thermal waters in the temperature range of 130 ± 10 °C, which can be taken as the most probable reservoir temperature. The subsurface temperature (137 °C) obtained from the mixing model further validated the results obtained from multicomponent geothermometry. This integrated multicomponent method and the simulation program used in this study take into account various processes (i.e. mixing, degassing, non-attainment of equilibrium, etc.) which affect the composition of the thermal fluids during its ascent to the surface. The statistical approach of ‘best clustering minerals’ used in this model helps to overcome the problems encountered in applying cation or single-component geothermometers in the medium-enthalpy geothermal systems.
      PubDate: 2019-08-09
       
  • Editorial
    • PubDate: 2019-06-29
       
  • Isotopic Composition and Origin of Sulfide and Sulfate Species of Sulfur
           in Thermal Waters of Jiangxi Province (China)
    • Abstract: Abstract The reduced sulfur species, sulfide, elemental and thiosulfate were considered in the thermal waters of Jiangxi Province for the first time. It is shown that the sulfur speciation content significantly varies and depends on the pH values. The major part of reduced sulfur refers to sulfide species in the nitric thermal waters, to elemental—in the carbon dioxide thermal waters. The presence of both reduced and oxidized sulfur speciation indicates the possibility of sulfide minerals hydrolysis and disproportionation of the product of this reaction (SO2) with the participation of hot water with the formation of elemental and sulfate sulfur. The isotopic composition of dissolved sulfate and sulfide sulfur speciation has shown that the process of bacterial reduction proceeds in the thermal waters, accompanied by accumulation of relatively heavy sulfur isotope in sulfates. Simultaneously with reduction, the oxidation of both sulfide minerals and newly formed hydrosulfide proceeds with formation of elemental, thiosulfates and also sulfates in the discharge zone was proceeded. It is shown that the process of sulfide oxidation mostly occurs in carbon dioxide thermal waters. Therefore, the elemental sulfur is predominant in carbon dioxide waters. The oxidation process is less significant in the nitric thermal waters, whereby the concentrations of sulfide ion are higher than sulfates. The ambiguous effect of sulfate reduction on the hydrogeochemical environment of the thermal waters is confirmed by the differing value of the carbon isotope ratio of HCO3− in the considered waters. The obtained isotopic composition data 34δS(SO42−) indicate host rocks as a source of sulfates in the thermal waters of Jiangxi Province.
      PubDate: 2019-06-13
       
  • An Integrated Isotope-Geochemical Approach to Characterize a Medium
           Enthalpy Geothermal System in India
    • Abstract: Abstract The Manuguru geothermal area, situated in the Telangana state, is one of the least explored geothermal fields in India. In this study, the chemical characteristics of the groundwater (thermal and non-thermal waters) are investigated to elucidate the source of the solutes dissolved in the water and to determine the approximate residence time of the thermal waters. The major hydrogeochemical processes controlling the groundwater geochemistry have been deciphered using multivariate statistical analysis, conventional graphical plots and geochemical modelling (PHREEQC). Geochemically different groundwater clusters (bicarbonate type, bicarbonate–chloride type and chloride type) can clearly be identified from the chemometric analysis, i.e. PCA and HCA. Thermal waters are mostly Na–HCO3 type having low EC and TDS compared to non-thermal groundwaters. Silicate weathering and ion exchange mainly contribute to the dissolved ion budget in the groundwater of the study area. The carbon isotopic composition of DIC (δ13C) points to silicate weathering with soil CO2 coming from C3 type of plants. Stable isotopes (δ18O, δ2H) data confirm the meteoric origin of the thermal waters with no oxygen-18 shift. The low tritium values of the thermal water samples reveal the long circulation time (> 50 years) of the recharging waters. Radiocarbon dating (14C) shows that the approximate residence time of the thermal waters ranges from 9952 to 18,663 year BP (before present).
      PubDate: 2019-04-26
       
  • Geochemistry of Chilean Rivers Within the Central Zone: Distinguishing the
           Impact of Mining, Lithology and Physical Weathering
    • Abstract: Abstract Several rivers of Chile from the latitude 30°–38° have been sampled during a stable anticyclonic period (October 2008). Firstly, our aim was to evaluate the dissolved chemical composition (major and trace elements) of poorly known central Chilean rivers. Secondly, we used a co-inertia analysis (see Dolédec and Chessel in Freshw Biol 31:277–294, 1994) to explore the possible relationships between the concentrations of elements and the environmental parameters [surface of the basin (km2)/mining activity (%)/average height (m)/watershed mean slope (%)/% of the surface covered by vegetation, sedimentary rocks, volcano-sedimentary rocks, volcanic rocks, granitoid rocks/erosion rate (mm/year)]. Globally, the major elements concentration could be explained by a strong control of mixed silicate and carbonate and evaporate lithology. The statistical treatment reveals that the highest metal and metalloids loads of Tinguiririca, Cachapoal, Aconcagua, Choapa, Illapel and Limari could be explained by the contribution of the mining activities in the uppermost part of these watersheds and/or by the higher geochemical background. Indeed, it remains difficult to decipher between a real mining impact and a higher geochemical background. Even if these rivers could be impacted by AMD process, the size of these watersheds is capable of diluting AMD waters by the alkaline character of tributaries that induce acid neutralization and decrease the level of metals and metalloids.
      PubDate: 2019-03-20
       
  • The Speciation and Mobility of Mn and Fe in Estuarine Sediments
    • Abstract: Abstract Dissolved and solid-phase speciation of Mn and Fe was measured in the porewaters of sediments recovered from three sites in the Greater St. Lawrence Estuary: the Saguenay Fjord, the Lower St. Lawrence Estuary (LSLE) and the Gulf of St. Lawrence (GSL). At all sites and most depths, metal organic ligand complexes (Mn(III)–L and Fe(III)–L) dominated the sedimentary porewater speciation, making up to 100% of the total dissolved Mn or Fe. We propose that these complexes play a previously underestimated role in maintaining oxidized soluble metal species in sedimentary systems and in stabilizing organic matter in the form of soluble metal–organic complexes. In the fjord porewaters, strong (log KCOND > 13.2) and weak (log KCOND < 13.2) Mn(III)–L complexes were detected, whereas only weak Mn(III)–L complexes were detected at the pelagic and hemipelagic sites of the GSL and LSLE, respectively. At the fjord site, Mn(III)–L complexes were kinetically stabilized against reduction by Fe(II), even when Fe(II) concentrations were as high as 57 μM. Only dissolved Mn(II) was released from the sediments to overlying waters, suggesting that Mn(III) may be preferentially oxidized by sedimentary microbes at or near the sediment–water interface. We calculated the dissolved Mn(II) fluxes from the sediments to the overlying waters to be 0.24 µmol cm−2 year−1 at the pelagic site (GSL), 11 µmol cm−2 year−1 at the hemipelagic site (LSLE) and 2.0 µmol cm−2 year−1 in the fjord. The higher benthic flux in the LSLE reflects the lower oxygen concentrations (dO2) of the bottom waters and sediments at this site, which favor the reductive dissolution of Mn oxides as well as the decrease in the oxidation rate of dissolved Mn(II) diffusing through the oxic layer of the sediment and its release to the overlying water.
      PubDate: 2019-03-15
       
 
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