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Paula López-Arce, Fernando Garrido, Javier García-Guinea, Andreas Voegelin, Jörg Göttlicher, Jose Miguel Nieto
Samples of an open-air pyrite roasting heap from the 19th century in the Riotinto mine area (SW Spain) and surrounding sediments and soil along a seasonal surface runoff channel were analyzed to study thallium (Tl) phase transformations during historical roasting of Tl-bearing arsenian pyrite, secondary weathering processes, Tl dispersion and current environmental pollution. Results from Electron Probe Microanalyses (EPMA) indicate an even distribution of Tl in pyrite grains of an ore sample (22 mg kg-1 total Tl), suggesting that Tl is incorporated in the pyrite structure rather than in discrete Tl-sulfide microparticles...
January 15, 2019: Science of the Total Environment
Mengtuan Ge, Dengjun Wang, Junwei Yang, Qiang Jin, Zongyuan Chen, Wangsuo Wu, Zhijun Guo
Remediating uranium contamination becomes a worldwide interest because of increasing uranium release from mining activities. Due to ubiquitous presence of pyrite and the application of iron-based technology, colloidal iron oxy-hydroxides such as akaganéite colloid (AKC) extensively exist in uranium polluted water at uranium tailing sites. In this context, we studied individual and co-transport of U(VI) and AKC in water-saturated sand columns at 50 mg/L AKC and environmentally relevant U(VI) concentrations (5...
October 5, 2018: Water Research
M García-Carmona, H García-Robles, C Turpín Torrano, E Fernández Ondoño, J Lorite Moreno, M Sierra Aragón, F J Martín Peinado
The present work assesses the residual pollution in the Guadiamar Green Corridor (SW, Spain) after a long-term aging process (18 years) since the accident of the Aznalcóllar pyrite mine. We have focused on the study of trace elements (Cu, Zn, Cd, As and Pb) in soils, their fractionation and the transference to the surrounding vegetation. The residual polluted areas are characterized by scattered plots with absence of vegetation, presenting high concentrations of trace elements, acidic pH and low organic carbon content...
February 10, 2019: Science of the Total Environment
Rebecca D McAuliffe, Daniel P Shoemaker
Non-stoichiometry is considered to be one of the main problems limiting iron pyrite, FeS2 , as a photovoltaic absorber material. Although some historical diffraction experiments have implied a large solubility range of FeS2-δ with δ up to 0.25, the current consensus based on calculated formation energies of intrinsic defects has lent support to line-compound behavior. Here it is shown that pyrite stoichiometry is relatively inflexible in both reductive conditions and in autogenous sulfur partial pressure, which produces samples with precise stoichiometry of FeS2 even at different Fe/S ratios...
October 1, 2018: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
Alexander J Krause, Benjamin J W Mills, Shuang Zhang, Noah J Planavsky, Timothy M Lenton, Simon W Poulton
Oxygen is essential for animal life, and while geochemical proxies have been instrumental in determining the broad evolutionary history of oxygen on Earth, much of our insight into Phanerozoic oxygen comes from biogeochemical modelling. The GEOCARBSULF model utilizes carbon and sulphur isotope records to produce the most detailed history of Phanerozoic atmospheric O2 currently available. However, its predictions for the Paleozoic disagree with geochemical proxies, and with non-isotope modelling. Here we show that GEOCARBSULF oversimplifies the geochemistry of sulphur isotope fractionation, returning unrealistic values for the O2 sourced from pyrite burial when oxygen is low...
October 4, 2018: Nature Communications
Kazumi Ozaki, Christopher T Reinhard, Eiichi Tajika
The possibility of low but nontrivial atmospheric oxygen (O2 ) levels during the mid-Proterozoic (between 1.8 and 0.8 billion years ago, Ga) has important ramifications for understanding Earth's O2 cycle, the evolution of complex life and evolving climate stability. However, the regulatory mechanisms and redox fluxes required to stabilize these O2 levels in the face of continued biological oxygen production remain uncertain. Here, we develop a biogeochemical model of the C-N-P-O2 -S cycles and use it to constrain global redox balance in the mid-Proterozoic ocean-atmosphere system...
October 3, 2018: Geobiology
Zhongcheng Li, Mengmin Xiao, Ying Zhou, Deliang Zhang, Hongzhen Wang, Xien Liu, Debao Wang, Wenpin Wang
Exploration and fabrication of low-cost but highly active electrocatalysts, alternatives to noble metals, have remained a challenge for overall water splitting reaction. To date, few studies have reported that the Earth-abundant pyrite FeS2 is catalytically active for hydrogen evolution reaction, while there is no study on the oxygen evolution reaction and overall water splitting reaction using pyrite FeS2 as an electrocatalyst. Here, we offer a facile hydrothermal approach for the synthesis of FeS2 nanoparticles by the reduction of FeCl3·6H2O with C5H10NS2Na·3H2O...
October 3, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Fernando Puente-Sánchez, Alejandro Arce-Rodríguez, Monike Oggerin, Miriam García-Villadangos, Mercedes Moreno-Paz, Yolanda Blanco, Nuria Rodríguez, Laurence Bird, Sara A Lincoln, Fernando Tornos, Olga Prieto-Ballesteros, Katherine H Freeman, Dietmar H Pieper, Kenneth N Timmis, Ricardo Amils, Víctor Parro
Cyanobacteria are ecologically versatile microorganisms inhabiting most environments, ranging from marine systems to arid deserts. Although they possess several pathways for light-independent energy generation, until now their ecological range appeared to be restricted to environments with at least occasional exposure to sunlight. Here we present molecular, microscopic, and metagenomic evidence that cyanobacteria predominate in deep subsurface rock samples from the Iberian Pyrite Belt Mars analog (southwestern Spain)...
October 1, 2018: Proceedings of the National Academy of Sciences of the United States of America
Wim Buijs, Ibnelwaleed A Hussein, Mohamed Mahmoud, Abdulmujeeb T Onawole, Mohammed A Saad, Golibjon R Berdiyorov
A common problem that faces the oil and gas industry is the formation of iron sulfide scale in various stages of production. Recently an effective chemical formulation was proposed to remove all types of iron sulfide scales (including pyrite), consisting of a chelating agent diethylenetriaminepentaacetic acid (DTPA) at high pH using potassium carbonate (K2 CO3 ). The aim of this molecular modeling study is to develop insight into the thermodynamics and kinetics of the chemical reactions during scale removal...
August 8, 2018: Industrial & Engineering Chemistry Research
Cheng-Feng Du, Qinghua Liang, Yun Zheng, Yubo Luo, Hui Mao, Qingyu Yan
Presented are the novel Ti3 C2 T x MXene-based nanohybrid that decorated by pyrite nanodots on its surface (denoted as FeS2 @MXene). The nanohybrid was obtained by the one-step sulfurization of self-assembled iron hydroxide@MXene precursor. When used for Li/Na-ion storage, the FeS2 @MXene nanohybrid present excellent rate capabilities. Particularly, for Li-ion storage, an elevated reversible specific capacity of 762 mAh g-1 at 10 A g-1 after 1000 cycles was achieved. And for Na-ion storage, the FeS2 @MXene nanohybrid also delivering a reversible specific capacity of 563 mAh g-1 after 100 cycles at a current density of 0...
October 10, 2018: ACS Applied Materials & Interfaces
Xinlong Li, Naoki Hiroyoshi, Carlito Baltazar Tabelin, Kosuke Naruwa, Chie Harada, Mayumi Ito
Pyrite, a common gangue mineral in complex sulfide ores and coals, is rapidly oxidized in water by ferric ions and dissolved oxygen to form a very acidic and heavy metal-laden leachate called acid mine drainage (AMD). Carrier-microencapsulation (CME) using Ti4+ , Si4+ , and Al3+ was reported as a promising new approach to prevent pyrite oxidation by forming a passivating barrier on the pyrite surface. In CME, the presence of Fe3+ -catecholate complexes is unavoidable but their effects on pyrite oxidation remain unclear...
September 17, 2018: Chemosphere
Yan Zhou, Rong Fan, Michael D Short, Jun Li, Russell C Schumann, Haolan Xu, Roger St C Smart, Andrea R Gerson, Gujie Qian
The aim of this study was to test the performance of a novel method for acid rock drainage (ARD) control through the formation of Al(OH)3 -doped passivating surface layers on pyrite. At pH 2.0 and 4.0, there was no obvious inhibition of the pyrite oxidation rate on addition of 20 mg L-1 Al3+ (added as AlCl3 ·6H2 O). In comparison, the pyrite oxidation rate at circumneutral pH (7.4 ± 0.4) decreased with increasing added Al3+ with ≈98% reduction in long-term (282 days) dissolution rates in the presence of 20 mg L-1 Al3+ ...
October 3, 2018: Environmental Science & Technology
Kaituo Shi, Keyong Wang, Haijun Yu, Zhigao Wang, Xueli Ma, Xiujuan Bai, Rui Wang
The Jinchang gold deposit has been extensively studied, but precise dates for its formation are debated. Native gold mainly occurs as inclusions within pyrite and quartz. In this study, we analysed quartz crystals coeval with gold precipitation from two different types of mineralization using the ArgusVI multi-collector noble gas mass spectrometer by the stepwise crushing technique to resolve the timing and genesis of gold mineralization. 40 Ar/39 Ar dating of quartz samples (J12Q) from breccia ore yields a plateau age of 109...
September 17, 2018: Scientific Reports
Melanie Schwermer, Alfred Längler, Katharina Fetz, Thomas Ostermann, Tycho Jan Zuzak
BACKGROUND: In Europe only few integrative pediatric wards exists and there are two German hospitals focusing on anthroposophic medicine as part of complementary and alternative medicine (CAM). Whilst the most common pediatric diseases are treated here, pseudocroup patients make up a large group in these hospitals, receiving conventional as well as anthroposophic therapies. However, effectiveness of these therapy concepts mostly based on physicians' experiences but clinical studies are hitherto missing...
October 2018: Complementary Therapies in Medicine
S Oberst, R K Niven, D R Lester, A Ord, B Hobbs, N Hoffmann
Worldwide, mineral exploration is suffering from rising capital costs, due to the depletion of readily recoverable reserves and the need to discover and assess more inaccessible or geologically complex deposits. For gold exploration, this problem is particularly acute. We propose an innovative approach to mineral exploration and orebody characterisation, based on the analysis of geological core data as a spatial dynamical system, using the mathematical tools of dynamical system analysis. This approach is highly relevant for orogenic gold deposits, which-in contrast to systems formed at chemical equilibrium-exhibit many features of nonlinear dynamical systems, including episodic fluctuations on various length and time scales...
August 2018: Chaos
Li-Zhu Liu, Zhen-Yuan Nie, Yi Yang, Xuan Pan, Xu Xia, Yu-Hang Zhou, Jin-Lan Xia, Li-Juan Zhang, Xiang-Jun Zhen, Hong-Ying Yang
For the first time, synchrotron radiation (SR) -based carbon K-edge X-ray absorption near edge structure (XANES) spectroscopy in-situ characterization was conducted to evaluate the evolution of superficial (about 10 nm) organic components of extracellular polymeric substances (EPS) of thermoacidophilic archaeon Acidianus manzaensis YN-25 acclimated with different energy substrates (FeS2 , CuFeS2 , S0 , FeSO4 ). The atomic force microscopy (AFM) morphology scanning showed that the strain acclimated with different energy substrates varied a lot in EPS amount...
September 1, 2018: Research in Microbiology
Hugh C Jenkyns
The two major oceanic anoxic events of the Cretaceous, those of the Early Aptian (OAE 1a) and the Cenomanian-Turonian boundary (OAE 2), registered some of the highest temperatures reconstructed for the Cretaceous Period, and are thought to be related to the input of volcanically derived carbon dioxide from one or more Large Igneous Provinces. Widely distributed deposition of marine organic matter, the hallmark of OAEs, and intensified silicate weathering in response to a globally accelerated hydrological cycle and/or reaction of seawater with freshly extruded basalt, are both potential mechanisms whereby the content of atmospheric carbon dioxide could have been drawn down to promote cooling, on the assumption that this potential effect was not offset by increased addition of this volcanically derived greenhouse gas...
October 13, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Stephan L Seibert, Michael E Böttcher, Florian Schubert, Thomas Pollmann, Luise Giani, Sumiko Tsukamoto, Manfred Frechen, Holger Freund, Hannelore Waska, Heike Simon, Tobias Holt, Janek Greskowiak, Gudrun Massmann
Organic-poor, permeable quartz sands are often present at land-sea transition zones in coastal regions. Yet, the biogeochemical cycles of carbon, sulfur, and iron are not well studied here. The aim of this work was, therefore, to improve our understanding regarding the chemical processes in these prominent coastal sediments. A 10 m core was collected at a dune base of the barrier island Spiekeroog, Germany, for this purpose. Additionally, groundwater was sampled from a multi-level well for one year to record seasonal hydrochemical variations...
February 1, 2019: Science of the Total Environment
William Stanley, Gordon Southam
Growth of two dissimilatory sulfate-reducing bacteria, Desulfosporosinus orientis (gram-positive) and Desulfovibrio desulfuricans (gram-negative), in a chemically defined culture medium resulted in similar growth rates (doubling times for each culture = 2.8 h) and comparable rates of H2 S generation (D. orientis = 0.19 nmol/L S2- per cell per h; D. desulfuricans = 0.12 nmol/L S2- per cell per h). Transmission electron microscopy of whole mounts and thin sections revealed that the iron sulfide mineral precipitates produced by the two cultures were morphologically different...
September 2018: Canadian Journal of Microbiology
Alain Manceau, Margarita Merkulova, Magdalena Murdzek, Valentina Batanova, Rafal Baran, Pieter Glatzel, Binoy K Saikia, Dogan Paktunc, Liliana Lefticariu
Pyrite (cubic FeS2 ) is the most abundant metal sulfide in nature and also the main host mineral of toxic mercury (Hg). Release of mercury in acid mine drainage resulting from the oxidative dissolution of pyrite in coal and ore and rock resulting from mining, processing, waste management, reclamation, and large construction activities is an ongoing environmental challenge. The fate of mercury depends on its chemical forms at the point source, which in turn depends on how it occurs in pyrite. Here, we show that pyrite in coal, sedimentary rocks, and hydrothermal ore deposits can host varying structural forms of Hg which can be identified with high energy-resolution XANES (HR-XANES) spectroscopy...
September 18, 2018: Environmental Science & Technology
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