bluuebunny/crossref_metadata_2025 huggingface dataset:
CNOP‐Based Adaptive Observation Network Designed for Improving Upstream Kuroshio Transport Prediction
Authors: Zhang Kun , Mu Mu , Wang Qiang , Yin Baoshu , Liu Shixuan
Published: June 2019

Using the Regional Ocean Modeling System and the conditional nonlinear optimal perturbation (CNOP) approach, this study explored a CNOP‐based adaptive observation system design with regard to improving the prediction of one seasonal upstream Kuroshio transport (UKT) reduction event. For comparison, investigations were also conducted using a set of random observation systems built within a sensitive area inferred from previous studies and a conventional observation system built at 18°N. For these observation systems, observation networks constructed using different numbers of observation sites and observation distances (i.e., the shortest distances between any two observation sites) were evaluated by performing observing system simulation experiments. Results showed that most assimilation experiments can improve the UKT prediction, indicating the importance of initial conditions. For all observation systems, large numbers of observation sites generally led to higher prediction benefits, whereas the effects of observation distances differed significantly. Overall, the CNOP‐based observation system exhibited the best performance. Optimal CNOP‐based observation networks were established using six or eight observation sites and observation distances of 140 or 165 km, which produced a mean prediction improvement of 43.1%. This preliminary work is expected to provide guidance on future observations in the upstream Kuroshio region and to help realistic UKT predictions.
Collapsing Complexity: Quantifying Multiscale Properties of Reef Topography
Authors: Duvall Melissa S. , Hench James L. , Rosman Johanna H.
Published: June 2019

Seafloor topography affects a wide range of physical and biological processes; therefore, collapsing the three‐dimensional structure of the bottom to roughness metrics is a common challenge in studies of marine systems. Here we assessed the properties captured by metrics previously proposed for the seafloor, as well as metrics developed to characterize other types of rough surfaces. We considered three classes of metrics: properties of the bottom elevation distribution (e.g., standard deviation), length scale ratios (e.g., rugosity), and metrics that describe how topography varies with spatial scale (e.g., Hölder exponents). The metrics were assessed using idealized topography and natural seafloor topography data from airborne lidar measurements of a coral reef. We illustrate that common roughness metrics (e.g., rugosity) can have the same value for topographies that are geometrically very different, limiting their utility. Application of the wavelet leaders technique to the reef data set demonstrates that the topography has a power law scaling behavior, but it is multifractal so a distribution of Hölder exponents is needed to describe its scaling behavior. Using principal component analysis, we identify three dominant modes of topographic variability, or ways metrics covary, among and within reef zones. Collectively, the results presented here show that coral reef topography is both multiscale and multifractal. While individual metrics that capture specific topography properties relevant to a given process may be suitable for some studies, many applications will require a set of metrics that includes statistics that capture how topography varies with spatial scale.
Weakening of the Teleconnection From El Niño–Southern Oscillation to the Arctic Stratosphere Over the Past Few Decades: What Can Be Learned From Subseasonal Forecast Models?
Authors: Garfinkel Chaim I. , Schwartz Chen , Butler Amy H. , Domeisen Daniela I. V. , Son Seok‐Woo , White Ian P.
Published: June 2019

While a connection between the El Niño–Southern Oscillation (ENSO) and the Northern Hemisphere wintertime stratospheric polar vortex appears robust in observational studies focusing on the period before 1979 and in many modeling studies, this connection is not evident over the past few decades. In this study, the factors that have led to the disappearance of the ENSO‐vortex relationship are assessed by comparing this relationship in observational data and in operational subseasonal forecasting models over the past few decades. For reforecasts initialized in December, the models simulate a significantly weaker vortex during El Niño than La Niña (LN) as occurred before 1979, but no such effect was observed to have occurred. The apparent cause of this is the eastern European and western Siberian height anomalies present during ENSO. The observed LN events were associated with persistent ridging over eastern Europe as compared to El Niño. Although the Subseasonal‐to‐Seasonal models are initialized with this ridge, the ridge quickly dissipates. As ridging over this region enhances wave flux entering the stratosphere, the net effect is no robust stratospheric response to ENSO in the observations despite a North Pacific teleconnection that would, in isolation, lead to less wave flux for LN. The anomalies in the eastern European sector in response to ENSO likely reflect unforced internal atmospheric variability.
Tracking Dissolved Organic Matter in Coastal Ecosystems
Authors: Thompson Elizabeth
Published: June 2019

Dissolved organic matter supports aquatic food webs and holds as much carbon as the atmosphere. A new study tracks which sources and processes play the biggest role in coastal systems.
Electron Diffusion Regions in Magnetotail Reconnection Under Varying Guide Fields
Authors: Chen L.‐J. , Wang S. , Hesse M. , Ergun R. E. , Moore T. , Giles B. , Bessho N. , Russell C. , Burch J. , Torbert R. B. , Genestreti K. J. , Paterson W. , Pollock C. , Lavraud B. , Le Contel O. , Strangeway R. , Khotyaintsev Yu V. , Lindqvist P.‐A.
Published: June 2019

Kinetic structures of electron diffusion regions (EDRs) under finite guide fields in magnetotail reconnection are reported. The EDRs with guide fields 0.14–0.5 (in unit of the reconnecting component) are detected by the Magnetospheric Multiscale spacecraft. The key new features include the following: (1) cold inflowing electrons accelerated along the guide field and demagnetized at the magnetic field minimum while remaining a coherent population with a low perpendicular temperature, (2) wave fluctuations generating strong perpendicular electron flows followed by alternating parallel flows inside the reconnecting current sheet under an intermediate guide field, and (3) gyrophase bunched electrons with high parallel speeds leaving the X‐line region. The normalized reconnection rates for the three EDRs range from 0.05 to 0.3. The measurements reveal that finite guide fields introduce new mechanisms to break the electron frozen‐in condition.
In Search of Winter Blocking in the Western North Pacific Ocean
Authors: Kim Seon‐Hwa , Kim Baek‐Min
Published: June 2019

We investigate winter blocking activity over the western North Pacific (WNP) through an intercomparison of four detection methods, which are categorized into two types (anomaly and reversal). Most of the blocking events in the anomaly‐based methods are initiated from the eastern North Pacific. Reversal‐based methods capture the blocking occurrence associated with Rossby wave breaking, especially cyclonic breaking. As the two types capture different aspects of WNP blocking, the resultant regional impact is also largely different. At the onset, anomaly‐based methods show a strong cold anomaly downstream of the blocking in conjunction with a Pacific/North America‐like pattern. Reversal‐based methods indicate a weak cold anomaly in company with a western Pacific‐like pattern, which appears downstream and upstream of the blocking in the local reversal and large‐scale reversal methods, respectively. At the end of WNP blocking, all methods show strong cold anomalies both upstream and downstream of the blocking.
Response to Channel Deepening of the Salinity Intrusion, Estuarine Circulation, and Stratification in an Urbanized Estuary
Authors: Ralston David K. , Geyer W. Rockwell
Published: June 2019

Modifications for navigation since the late 1800s have increased channel depth (H) in the lower Hudson River estuary by 10–30%, and at the mouth the depth has more than doubled. Observations along the lower estuary show that both salinity and stratification have increased over the past century. Model results comparing predredging bathymetry from the 1860s with modern conditions indicate an increase in the salinity intrusion of about 30%, which is roughly consistent with the H5/3 scaling expected from theory for salt flux dominated by steady exchange. While modifications including a recent deepening project have been concentrated near the mouth, the changes increase salinity and threaten drinking water supplies more than 100 km landward. The deepening has not changed the responses to river discharge (Qr) of the salinity intrusion (~Qr−1/3) or mean stratification (Qr2/3). Surprisingly, the increase in salinity intrusion with channel deepening results in almost no change in the estuarine circulation. This contrasts sharply with local scaling based on local dynamics of an H2 dependence, but it is consistent with a steady state salt balance that allows scaling of the estuarine circulation based on external forcing factors and is independent of depth. In contrast, the observed and modeled increases in stratification are opposite of expectations from the steady state balance, which could be due to reduction in mixing with loss of shallow subtidal regions. Overall, the mean shift in estuarine parameter space due to channel deepening has been modest compared with the monthly‐to‐seasonal variability due to tides and river discharge.
Field Correlations in Surface Plasmon Speckle
Authors: Foreman Matthew R.
Published: June 2019

In this work fluctuations in the electric field of surface plasmon polaritons undergoing random scattering on a rough metallic surface are considered. A rigorous closed form analytic expression is derived describing second order correlations in the resulting plasmon speckle pattern assuming statistically stationary and isotropic roughness. Partially coherent planar Schell-model source fields can also be described within the developed framework. Behaviour of the three-dimensional degree of cross polarisation and spectral degree of coherence is also discussed. Expressions derived take full account of dissipation in the metal with non-universal behaviour exhibited within the correlation length of the surface and source fields.
An easy access to topical gels of an anti-cancer prodrug (5-fluorouracil acetic acid) for self-drug-delivery applications
Authors: Chakraborty Poulami , Dastidar Parthasarathi
Published: June 2019

An easy access to topical gels (both hydro- and organogels) derived from an anti-cancer prodrug namely 5-fluorouracil acetic acid (5-FuA) achieved by exploiting a simple salt formation strategy is reported for the first time.
Nickel-catalyzed monofluoromethylation of (hetero)aryl bromides via reductive cross-coupling
Authors: Yin Han , Sheng Jie , Zhang Kai-Fan , Zhang Zi-Qi , Bian Kang-Jie , Wang Xi-Sheng
Published: June 2019

Nickel-catalyzed direct monofluoromethylation of (hetero)aryl bromides with industrial raw material BrCH2F by reductive cross-coupling has been developed.
An effectivecis-β-octahedral Mn(iii) SALPN catalyst for the Mukaiyama–Isayama hydration of α,β-unsaturated esters
Authors: Donnelly Paul S. , North Andrea J. , Radjah Natalia Caren , Ricca Michael , Robertson Angus , White Jonathan M. , Rizzacasa Mark A.
Published: June 2019

Twocis-β-MnIIISALPN catalysts were synthesised and tested in the Mukaiyama–Isayama hydration of α,β-unsaturated esters.
Quantum chemical models for the absorption of endohedral clusters on Si(111)-(7 × 7): a subtle balance between W–Si and Si–Si bonding
Authors: Jin Xiao , Arcisauskaite Vaida , McGrady John E.
Published: June 2019

The absorption of endohedral clusters on Si(111)-7 × 7 generates a new bond between W and a surface silicon adatom.
Defect-induced photoluminescence from gallium-doped zinc oxide thin films: influence of doping and energetic ion irradiation
Authors: Gupta Himanshi , Singh Jitendra , Dutt R. N. , Ojha Sunil , Kar Soumen , Kumar Ravi , Reddy V. R. , Singh Fouran
Published: June 2019

PL spectra of the pristine and irradiated GZO thin films and schematic of defect energy levels responsible for visible emission.
Structure–property correlations, defect driven magnetism and anomalous temperature dependence of magnetic coercivity in PbTi1−xFexO3(0 ≤x≤ 0.5) systems
Authors: Hussain Shahzad , Asim Muhammad , Naveed-Ul-Haq M. , Rafique Mohsin , Tabassam Lubna , Arif Saira , Webers Samira , Rehman Azizur
Published: June 2019

The search for new multiferroic materials is on the rise due to their potential applications in an advanced generation of highly efficient multifunctional devices.
Cation exchange reversibly switches rotor speed and is monitored by a networked fluorescent reporter
Authors: Özer Merve S. , Paul Indrajit , Goswami Abir , Schmittel Michael
Published: June 2019

The three-step transformation of a turnstile into a zinc rotor (8 kHz) and then into a copper rotor (30 kHz) was achieved with the last transformation being monitored by a fluorescence reporter.
Nonadiabatic dynamics with quantum nuclei: simulating charge transfer with ring polymer surface hopping
Authors: Ghosh Soumya , Giannini Samuele , Lively Kevin , Blumberger Jochen
Published: June 2019

Exploring effects of quantizing nuclei in non-adiabatic dynamics for simulating charge transfer in a dimer of “ethylene-like-molecules” at different temperatures.
Suzuki–Miyaura coupling revisited: an integrated computational study
Authors: Yaman Tolga , Harvey Jeremy N.
Published: June 2019

Computation is used to revisit the mechanism of the Suzuki–Miyaura coupling mechanism.
Facile synthesis of 2-substituted benzo[b]furans and indoles by copper-catalyzed intramolecular cyclization of 2-alkynyl phenols and tosylanilines
Authors: Rong Zhouting , Gao Kexin , Zhou Lei , Lin Jianyuan , Qian Guoying
Published: June 2019

A facile and inexpensive copper-catalyzed method was developed for the synthesis of 2-substituted benzo[b]furans and indoles.
Direct synthesis of covalent triazine-based frameworks (CTFs) through aromatic nucleophilic substitution reactions
Authors: Chen Tao , Li Wen-Qian , Hu Wei-Bo , Hu Wen-Jing , Liu Yahu A. , Yang Hui , Wen Ke
Published: June 2019

Triazine-based frameworks (CTFs) were synthesized through a new synthetic strategy in which C–C bonds were formed through aromatic nucleophilic substitution reaction.
Controllable TiO2 coating on the nickel-rich layered cathode through TiCl4 hydrolysis via fluidized bed chemical vapor deposition
Authors: Li Xinxin , Shi Hebang , Wang Bo , Li Na , Zhang Liqiang , Lv Pengpeng
Published: June 2019

Surface coating of metal oxides is an effective approach for enhancing the capacity retention of a nickel-rich layered cathode.
A novel fabrication method of copper–reduced graphene oxide composites with highly aligned reduced graphene oxide and highly anisotropic thermal conductivity
Authors: Nazeer Faisal , Ma Zhuang , Xie Yitong , Gao Lihong , Malik Abdul , Khan Muhammad Abubaker , Wang Fuchi , Li Hezhang
Published: June 2019

Highly aligned rGO with anisotropic thermal conductivity was obtained in this work.
Exsolution of Fe–Ni alloy nanoparticles from (La,Sr)(Cr,Fe,Ni)O3 perovskites as potential oxygen transport membrane catalysts for methane reforming
Authors: Papargyriou Despoina , Miller David Noel , Sirr Irvine John Thomas
Published: June 2019

Tuning methane conversion at emergent Fe–Ni alloy nanoparticles through control of perovskite composition.
All-polymer solar cells based on a novel narrow-bandgap polymer acceptor with power conversion efficiency over 10%
Authors: Wu Jingnan , Meng Yuan , Guo Xia , Zhu Lei , Liu Feng , Zhang Maojie
Published: June 2019

A new narrow bandgap polymer acceptor (PN1) based on a fused-ring small molecule acceptor as the core building block was designed and developed. The optimal all-polymer solar cell based on the blend of PM6 and PN1 achieved an outstanding power conversion efficiency of 10.5% with a high open-circuit voltage of 1.0 V, a short circuit current density of 15.2 mA cm−2 and a fill factor of 0.69.
3D hierarchical V–Ni-based nitride heterostructure as a highly efficient pH-universal electrocatalyst for the hydrogen evolution reaction
Authors: Dong Xue , Yan Haijing , Jiao Yanqing , Guo Dezheng , Wu Aiping , Yang Ganceng , Shi Xia , Tian Chungui , Fu Honggang
Published: June 2019

A 3D hierarchical V–Ni-based nitride heterojunction anchored on carbon cloth (VN@Ni3N–Ni/CC) was designed as a promising pH-universal hydrogen evolution reaction electrocatalyst.
Effectively restricting MnSi precipitates for simultaneously enhancing the Seebeck coefficient and electrical conductivity in higher manganese silicide
Authors: Liu Wei-Di , Shi Xiao-Lei , Moshwan Raza , Sun Qiang , Yang Lei , Chen Zhi-Gang , Zou Jin
Published: June 2019

Introducing Mg2Si into higher manganese silicide synthesis successfully suspended the precipitation of MnSi, leading to reduced effective mass, reduced optimized carrier concentration, and enhanced figure of merit,zT.
Changing substrate specificity and iteration of amino acid chain elongation in glucosinolate biosynthesis through targeted mutagenesis ofArabidopsismethylthioalkylmalate synthase 1
Authors: Petersen Annette , Hansen Lea Gram , Mirza Nadia , Crocoll Christoph , Mirza Osman , Halkier Barbara Ann
Published: June 2019

Methylthioalkylmalate synthases catalyse the committing step of amino acid chain elongation in glucosinolate biosynthesis. As such, this group of enzymes plays an important role in determining the glucosinolate composition of Brassicaceae species, including Arabidopsis thaliana. Based on protein structure modelling of MAM1 from A. thaliana and analysis of 57 MAM sequences from Brassicaceae species, we identified four polymorphic residues likely to interact with the 2-oxo acid substrate. Through site-directed mutagenesis, the natural variation in these residues and the effect on product composition were investigated. Fifteen MAM1 variants as well as the native MAM1 and MAM3 from A. thaliana were characterised by heterologous expression of the glucosinolate chain elongation pathway in Escherichia coli. Detected products derived from leucine, methionine or phenylalanine were elongated with up to six methylene groups. Product profile and accumulation were changed in 14 of the variants, demonstrating the relevance of the identified residues. The majority of the single amino acid substitutions decreased the length of methionine-derived products, while approximately half of the substitutions increased the phenylalanine-derived products. Combining two substitutions enabled the MAM1 variant to increase the number of elongation rounds of methionine from three to four. Notably, characterisation of the native MAMs indicated that MAM1 and not MAM3 is responsible for homophenylalanine production. This hypothesis was confirmed by glucosinolate analysis in mam1 and mam3 mutants of A. thaliana.
When the tale comes true: multiple populations and wide binaries in the Orion Nebula Cluster
Authors: Jerabkova Tereza , Beccari Giacomo , Boffin Henri M. J. , Petr-Gotzens Monika G. , Manara Carlo F. , Prada Moroni Pier Giorgio , Tognelli Emanuele , Degl’Innocenti Scilla
Published: June 2019

Context. Recently published high-quality OmegaCAM photometry of the 3 × 3 deg around the Orion Nebula Cluster (ONC) in r, and i filters revealed three well-separated pre-main sequences in the color-magnitude diagram (CMD). The objects belonging to the individual sequences are concentrated toward the center of the ONC. The authors concluded that there are two competitive scenarios: a population of unresolved binaries and triples with an exotic mass ratio distribution, or three stellar populations with different ages (≈1 Myr age differences).

Aims. We use Gaia DR2 in combination with the photometric OmegaCAM catalog to test and confirm the presence of the putative three stellar populations. We also study multiple stellar systems in the ONC for the first time using Gaia DR2.

Methods. We selected ONC members based on parallaxes and proper motions and take advantage from OmegaCAM photometry that performs better than Gaia DR2 photometry in crowded regions. We identify two clearly separated sequences with a third suggested by the data. We used Pisa stellar isochrones to estimate ages of the stellar populations with absolute magnitudes computed using Gaia parallaxes on a star by star basis.

Results. (1) We confirm that the second and third sequence members are more centrally concentrated toward the center of the ONC. In addition we find an indication that the parallax and proper motion distributions are different among the members of the stellar sequences. The age difference among stellar populations is estimated to be 1−2 Myr. (2) We use Gaia proper motions and other measures to identify and remove as many unresolved multiple system candidates as possible. Nevertheless we are still able to recover two well-separated sequences with evidence for the third one, supporting the existence of the three stellar populations. (3) Due to having ONC members with negligible fore- or background contamination we were able to identify a substantial number of wide binary objects (separation between 1000 and 3000 au) and with relative proper motions of the binary components consistent with zero. This challenges previously inferred values that suggested no wide binary stars exist in the ONC. Our inferred wide-binary fraction is ≈5%.

Conclusions. We confirm the three populations correspond to three separated episodes of star formation. Based on this result, we conclude that star formation is not happening in a single burst in this region. In addition we identify 5% of wide-binary stars in the ONC that were thought not to be present.
J-PLUS: Discovery and characterisation of ultracool dwarfs using Virtual Observatory tools
Authors: Solano E. , Martín E. L. , Caballero J. A. , Rodrigo C. , Angulo R. E. , Alcaniz J. , Borges Fernandes M. , Cenarro A. J. , Cristóbal-Hornillos D. , Dupke R. A. , Alfaro E. , Ederoclite A. , Jiménez-Esteban F. , Hernandez-Jimenez J. A. , Hernández-Monteagudo C. , Lopes de Oliveira R. , López-Sanjuan C. , Marín-Franch A. , Mendes de Oliveira C. , Moles M. , Orsi A. , Schmidtobreick L. , Sobral D. , Sodré L. , Varela J. , Vázquez Ramió H.
Published: June 2019

Context. Ultracool dwarfs are objects with spectral types equal to or later than M7. Most of them have been discovered using wide-field imaging surveys. The Virtual Observatory has proven to be very useful for efficiently exploiting these astronomical resources.

Aims. We aim to validate a Virtual Observatory methodology designed to discover and characterise ultracool dwarfs in the J-PLUS photometric survey. J-PLUS is a multiband survey carried out with the wide-angle T80Cam optical camera mounted on the 0.83 m telescope JAST/T80 in the Observatorio Astrofísico de Javalambre. We make use of the Internal Data Release covering 528 deg2.

Methods. We complemented J-PLUS photometry with other catalogues in the optical and infrared using VOSA, a Virtual Observatory tool that estimates physical parameters from the spectral energy distribution fitting to collections of theoretical models. Objects identified as ultracool dwarfs were distinguished from background M giants and highly reddened stars using parallaxes and proper motions from Gaia DR2.

Results. We identify 559 ultracool dwarfs, ranging from i = 16.2 mag to i = 22.4 mag, of which 187 are candidate ultracool dwarfs not previously reported in the literature. This represents an increase in the number of known ultracool dwarfs of about 50% in the region of the sky we studied, particularly at the faint end of our sensitivity, which is interesting as reference for future wide and deep surveys such as Euclid. Three candidates are interesting targets for exoplanet surveys because of their proximity (distances less than 40 pc). We also analysed the kinematics of ultracool dwarfs in our catalogue and found evidence that it is consistent with a Galactic thin-disc population, except for six objects that might be members of the thick disc.

Conclusion. The results we obtained validate the proposed methodology, which will be used in future J-PLUS and J-PAS releases. Considering the region of the sky covered by the Internal Data Release used in this work, we estimate that 3000–3500 new ultracool dwarfs will be discovered at the end of the J-PLUS project.
REE in waters and bottom sediments of salt lakes of Southeastern Transbaikalia, Russia
Authors: Borzenko Svetlana V. , Zamana Leonid V.
Published: June 2019

This paper presents our analysis of the distribution of REE in mineral chloride and soda lakes of Southeastern Transbaikalia. With increasing water salinity, it was determined that concentrations of dissolved HREE increased. The prevalence in absolute concentrations of MREE and HREE was observed in lakes with the development of bacterial processes (sulfate-reduction). A geochemical barrier for accumulating the LREE in the waters can be fluoro-carbonates. The saturation degree of fluorcarbonates in soda lakes can be several orders higher than in chloride lakes. Under oxidizing conditions Ce(OH)4 can be formed and, in a reducing environment – Ce(OH)3.
Hydrogeochemistry and distribution of potentially toxic elements in a metallogenic province – The Iberian Pyrite Belt, Portugal
Authors: Gomes Patricia , Valente Teresa , Costa Maria Rosário , Fonseca Rita , Costa Ana , Neves Orquídea , Moreno Filipa
Published: June 2019

Contamination by acid drainage is an environmental problem in mineralized regions, especially in the surroundings of sulphide mines. The water rock interaction process involves the oxidative dissolution of sulphides, naturally or by mining activity, that generates acidity which, in turn, produces sulfate, and water pollution by sulphide-hosted metals. The particular geology of the Iberian Pyrite Belt (IPB) in the southwestern Iberian Peninsula creates the ideal conditions for such water contamination. Different water types were sampled at 28 locations across the entire IBP metallogenetic province. Anions, metals, and arsenic were analysed to assess the influence of acid drainage. The results demonstrate the sulfate nature of waters in the vicinity of mines. Other types of water in the IPB region are mainly mixed chloride and bicarbonate (river and groundwater) and mixed and sodium-bicarbonate (lakes) types. Water quality assessment indicated strong contamination of surface waters that are directly influenced by mine wastes. There is the additional concern that some lakes and groundwaters exhibit concentrations of potentially toxic elements (e.g. Al, As) that are above the regulatory limits established by the European Commission Water Framework Directive.
High chloride, sulphate and fluoride concentrations in clay-rich aquitard porewater, the North China Plain: evidence of geochemical behavior
Authors: Han Dongmei , Cao Guoliang , Love Andrew J.
Published: June 2019

The focus of this investigation was to constrain the porewater chemistry from tracer and ion profiles in a 128 m thick clay-rich sequence of Quaternary sediments comprising the clay, silt and fine sand formation in the North China Plain. Porewater are much more saline (1.1-71.0 g/L) than the lower confined groundwaters (0.3-1.3g/L). Chloride profiles from aqueous extraction (AE) (ranging from 117 to 3260 mg/L) generally keep good consistent with that obtained from squeezing test (ST). However, the sulphate and fluoride concentrations by AE (ranging from 340 to 48,700 mg/L and from 8.8 to 144 mg/L, respectively) are far greater than that by ST. Dissolution of evaporites may be responsible for the high Cl/Br ratios greater than 1000, probably indicating recharge occurred during much wetter periods. The original stable isotopic and chemical compositions in the aquitard porewater have been modified by transpiration and evaporation processes concentrating Cl and causing isotopic enrichment during their formation periods. Dissolution of fluorite, hieratite, and cryolite caused by weathering behavior and ion-exchange reactions should be responsible for the high fluoride concentrations in the aquitard porewater. High sulphate levels found in aqueous samples may arise from pyrite oxidation during sampling, storage and/or porewater extraction procedure.
Diurnal chemistry of two contrasting stream types, Taylor Valley, McMurdo Dry Valley Region, Antarctica
Authors: Harmon Russell S. , Leslie Deborah L. , Lyons W. Berry , Welch Kathleen A. , McKnight Diane M.
Published: June 2019

Numerous ephemeral streams flow within the McMurdo Dry Valley Region of Antarctica that transport glacial meltwater to perennially ice-covered, closed-basin lakes during the austral summer. The diurnal behavior for two Taylor Valley streams of different character was examined during the summer of 2010-11. Andersen Creek is a short, 1st-order proglacial stream, whereas Von Guerard Stream is a long, high-order stream with an extensive hyporheic zone that has a substantial cyanobacterial algal mat community in its middle reaches. Both streams display strong daily cycles for temperature, electrical conductivity, dissolved oxygen, and pH. Conductivity varies in concert with flow, with solute dilution occurring during the daily high-flow pulse. Dissolved oxygen co-varies strongly with pH at Andersen Creek but not for Von Guerard Stream. Each stream has a distinct geochemical character that for Andersen Creek is a direct reflection of its glacial source, unmodified by secondary effects, whereas that for Von Guerard Stream is modulated by its resident algal mat community and through extensive hyporheic zone interaction and exchange.
Geochemistry of strontium in fresh underground waters of the Sredneobskoy basin (Tomsk region, Russia)
Authors: Ivanova Irina
Published: June 2019

In the central part of Western Siberia a study of the chemical composition of fresh underground waters in the upper 600 m of the Sredneobskoy artesian basin was carried out. It was shown that underground waters generally contain high concentrations of strontium. The minimum concentrations of Sr are typical for Neogene-Quaternary sediments (600 µg/L), maximum values in the waters of the Upper Cretaceous sediments (more than 1300 µg/L). The study of strontium accumulation mechanisms in drinking underground waters is undoubtedly an important issue, as strontium is a biologically active element. Especially dangerous is the consumption of underground waters with a calcium-strontium ratio less than 100, that is the hydrogeochemical precondition for Urov endemic (Kashin-Beck disease). According to the calcium/strontium ratios data waters of the Neogene-Quaternary and Paleogene sediments selected in the south-western part of the Tomsk region are unsuitable for drinking water supply. Underground waters are shown to be in equilibrium with Al and Fe hydroxides; Ca, Mg, Fe carbonates; and clay minerals, including ferruginous. Increased strontium content in aquifers is determined not only by the chemical composition of the water-bearing rocks, but also increasing resident time of water rock interaction.
Recharge of natural mineral water Jingyu County, northeastern China
Authors: Liang Xiujuan , Tian Hui , Xiao Changlai , Li Mingqian , Sun Ying , Li Yinxi
Published: June 2019

A light stable isotope investigation of the source of natural mineral water in Jingyu County indicates an origin predominantly from atmospheric precipitation. As water-rock interaction occurs in the runoff process, SiO2 in the basaltic aquifer is dissolved, forming a metasilicate-type mineral water. The average residence time of natural mineral water in the stratum is 20 to 56 years.
Rare-earth elements in groundwater of the abandoned Levikha copper mine (Middle Urals, Russia)
Authors: Rybnikov Petr A. , Rybnikova Liudmila S.
Published: June 2019

The distribution of REE in groundwater of the catchments, which were formed during the long-term operation of copper mines in the Middle Urals (Russia), was studied. The groundwater composition reflects a significant removal of REE from water-bearing rocks, which leads to their enrichment by several orders of magnitude relative to the oceans, surface water and groundwater. Maximum REE values (up to 15 mg/L) were recorded in groundwater discharged to the surface in the collapse zone (pH=3.5). In mine shafts REE values do not exceed 0.3 mg/L. Water of mine wastes occupy an intermediate position: here REE content varies from 0.5 to 6.5 mg/L. The degree of REE fractionation in mine waters is lower than in oceanic, surface and underground waters of the active water exchange zone at much higher contents. The chemical composition of groundwater of the abandoned copper mine is determined by hypogene processes and structure of the mineralized supergene zone, its mineralogical composition, and oxidation-reduction conditions.
Influence of changes in microbial cell membrane composition on isotopic fractionation of nitrate during denitrification
Authors: Wunderlich Anja , Heipieper Hermann J. , Elsner Martin , Einsiedl Florian
Published: June 2019

Pure cultures of Thauera aromatica were stressed by the addition of the toxic solvents 1-octanol and 4-chlorophenol causing adaptive modifications in their cell-membrane fatty acid composition. At the same time, we investigated the isotopic fractionation in δ15N-NO3- during denitrification. We observed a change in the degree of saturation (DoS) of the bacteria as a reaction to solvent stress and a higher degree of saturation was directly correlated to the concentration of solvents in the cell membrane. The enrichment factor ε15N-NO3- during denitrification showed a linear dependency to the DoS as well as to the membrane solvent concentration. Denitrifying bacteria thus may express less negative ε15N-NO3- when they are exposed to environmental stress that changes their cell membrane composition.
Abiogenic formation of H2, light hydrocarbons and other short-chain organic compounds within the serpentinite mud volcanoes of the Marianna Trench
Authors: Sissmann Olivier , Price Roy , Elvert Marcus , Heuer Verena B. , Prieto Xavier , Monnin Christophe , Rouchon Virgile , Noirez Sonia , Beaumont Valérie , Ammouïal Jérémie , Kohler Eric , Menzies Catriona , Ryan Jeffrey , Takai Ken
Published: June 2019

Serpentinite-hosting mud volcanoes, located in the Marianna forearc subduction zone, were drilled during IODP Expedition 366. Recovered samples from Asùt Tesoru seamount provide new insights on the generation of organic matter in deep environments. Short-chain alcohols, volatile fatty acids and light hydrocarbons are produced within hyperalkaline pore fluids (pH 12.5) rich in H2. The stable isotope values of those species show heavy δ13C values, suggesting a formation process through Fischer-Tropsch-Type reactions. This close isotopic study brings new constraints on the reaction pathways leading to the formation of not only light hydrocarbons, but also of short-chain organic molecules. These compounds may serve as precursors of building blocks essential to life in deep oceanic settings.
Numerical and experimental study of suffosion/clogging in deformable porous media
Authors: Khramchenkov Maxim , Khramchenkov Eduard , Garaeva Anastasiya
Published: June 2019

Mathematical model and experiment on suffosion/clogging process are presented. The model is based on the theory of flow in deformable porous media with mass-variable skeleton. It is shown that clogging occurs at a distance from injecting borehole. It is caused by precipitation of particles which were eroded by grounwater flow during the suffosion of the solid skeleton near the borehole.
Thermodynamic modeling of water vapor influence on development process of the lower-Karmalinsky bituminous deposit by the sagd method
Authors: Korolev Eduard , Bakhtin Anatoly , Eskin Aleksey , Barieva Enza , Gabdelvalieva Rezeda , Korolev Albert
Published: June 2019

The development of the Lower-Karmalinsky bituminous deposit is currently made by the SAGD method. However, focusing on the reduction of bitumen viscosity, the problem of mineral phase’s transformation at the reservoir due to anthropogenic impact overlooked. In this work, using thermodynamic modeling, shown that the injection of superheated steam into bitumen-saturated sandstone layer will lead to the dissolution of calcite cement.
Effect of soil water saturation on slope stability: Tomsk case study
Authors: Brakorenko Natalia , Leonova Anna , Nikitenkov Aleksey
Published: June 2019

We investigate in this article the impact of soil water saturation on the slope stability, using a site in Tomsk city as a case study. The dependency of the shear strength parameters of soil on the degree of soil water saturation has been demonstrated. The paper also provides equations for the calculation of slope stability coefficient under different values of soil water saturation.
X-ray absorption spectroscopy study of the chemistry of «invisible» Au in arsenian pyrites
Authors: Filimonova Olga , Trigub Alexander , Nickolsky Maximilian , Kovalchuk Elena , Abramova Vera , Rovezzi Mauro , Belogub Elena , Vikentyev Ilya , Tagirov Boris
Published: June 2019

Arsenian pyrite is an abundant mineral occurring in many geological settings at the Earth’s surface, including hydrothermal ore deposits which are the main source of Au. So-called “invisible” (or refractory) form of Au is present in pyrites in all types of these deposits, and its concentration is often directly correlated with As content. Here we report results of the investigation of the local atomic structure of Au in natural (Cu-Au-porphyry) and synthetic (450°C/ 1 kbar, 300°C/ Psat) As-free and As-bearing pyrites by means of X-ray absorption spectroscopy (XAS). In addition, the state of As was determined in pyrite samples from Carlin-type deposit. XANES/EXAFS measurements, compiled with previously published data, revealed the chemical state (valence state, local atomic environment) of Au and As in arsenian pyrites. Au is present in the solid solution state (Au1+ in the Fe position, octahedrally coordinated by S atoms), as well as in Au1+2S clusters (Au1+ linearly coordinated by 2 S atoms). The admixture of As has no effect on the Au valence state and Au-S interatomic distance, except one synthetic sample containing a minor amount of FeAsS. Arsenic mostly incorporates into the anion site in pyrite lattice (S1-↔As1-). Our data demonstrate that pyrites of hydrothermal origin can host up to ~300 ppm of structurally bound “invisible” Au independently of As content.
Acidic drainage in carbonate rocks
Authors: Ryzhenko Boris , Limanseva Oksana , Cherkasova Elena
Published: June 2019

Thermodynamic simulation of the system “Rocks of Pavlovskoe polymetallic deposit – water – atmosphere gases” predicts aqueous concentrations from mineral solubilities and speciation with the HCh geochemical code. It is shown the model solutions are alkaline and rich in some microelements (As, Cd, Se, Co, Cr, Cu, Ni, Pb, Ga, Ge, Sr, In); their concentrations are overcome MPC, especially on the ore storage site.
Geochemistry and Fe speciation in active volcanic environments – the case of Fogo Island, Cape Verde
Authors: Marques Rosa , Vieira Bruno J.C. , Prudêncio Maria Isabel , Waerenborgh João Carlos , Dias Maria Isabel , Russo Dulce , Rocha Fernando , Silva Teresa , Ruiz Francisco
Published: June 2019

Topsoils developed in different geological formations/ages, and the top layer of the lava flow from the most recent eruption (2014/2015) of Fogo Island (Cape Verde archipelago), were studied. The specific objectives of this work are: i) to estimate the REE contents and patterns in the whole sample of topsoils developed on different geological formations/ages and their correlation with the iron speciation; and ii) to study the top layer of a lava flow from the most recent eruption after two years of exposure. REE contents are in general higher in the topsoils of the pre-caldera than in those developed on the post-caldera formation, particularly the light REE probably due to their incorporation into hematite. Positive Eu anomalies found in recent topsoils suggest the existence of hydrothermal processes with intrusion of hot fluids with higher concentration of Eu2+. In the top layer of the lava flow of the most recent eruption, Fe is incorporated in pyroxenes and iron oxides (magnetite and/or maghemite). This study can be a benchmark for further knowledge of the chemical evolution and weathering rate in semi-arid climate of Fogo Island.
Deposits in utilized Icelandic high-temperature systems
Authors: Ármannsson Halldór
Published: June 2019

The most common scales in 7 utilized Icelandic high-temperature geothermal systems are calcite, amorphous silica, magnesium silicates, iron silicates, aluminium silicates and metal sulphides. They are mostly controlled by adjustment of temperature and pressure although chemical inhibition may be preferred due to production capacity. Reaming of wells by drilling and physical removal from surface equippment or acid cleaning may be needed.
Surface and groundwater hydrochemistry in the mid-Gregory Rift, Kenya: first impressions and potential implications for geothermal systems
Authors: Burnside Neil M. , Montcoudiol Nelly , Boyce Adrian J.
Published: June 2019

The University of Glasgow has a long tradition of scientific endeavour in the Gregory Rift Valley. This paper details some of the history and inspiration behind current hydrological efforts and details results from a 2016 field excursion to this region. A range of surface and ground waters were sampled and analysed for physical, chemical, and stable isotope composition as scoping investigation into geothermal-related hydrological systems. The results allow us to make some initial observations that will be followed up by additional multi-seasonal data collection. Our initial results show clear chemical and isotopic signals for river, lake, hot spring and Menengai geothermal well waters.
The role of humic substances in the speciation of metals in natural waters
Authors: Dinu Marina I.
Published: June 2019

The paper analyzes currently applied methodological approaches to evaluating the speciation of metals in natural waters and presents literature data and original author’s experimental results on the forms of metals in natural waters in various natural–climatic zones in Russia and other countries. Data are presented on the geochemical specifics of the distribution of metals between their forms in lakes RF.
Trace elements in nature water of the Naryksko-Ostashkinskaya area (Kuzbass, Russia)
Authors: Lepokurova Olesya , Domrocheva Eugenia
Published: June 2019

This paper presents data on the trace element composition of lake waters, river waters and groundwater in the area of coalbed methane production. The concentration dependences of some components on the mineralization, organic matter and depth are revealed. It is shown that underground waters of coal deposits are most enriched in microelements.
Soils’ role in the formation of groundwater composition and mineralization (on example of the Tatarstan Republic)
Authors: Musin Rustam , Korolev Eduard , Zotina Ksenia
Published: June 2019

The upper part of the section of the Tatarstan Republic is composed of polyfacial Middle-Upper Permian, Mesozoic, and Pliocene-Quaternary sediments. Surface and ground water are characterized here by wide variability of composition and salinity. These variations are determined by a complex of natural and technogenic factors. The most important natural factor is the interaction of precipitation and their derivatives with soils and rocks of the section. Water extracts from the main soil varieties were analyzed on the basis of distilled and thawed snow water in order to evaluate this interaction. The compositions of water extracts are compared with the compositions of the least mineralized spring waters. The components which are supplied in the underground hydrosphere by the soils are determined. It is shown that 50-80% of the ground water composition, which generate outside the zones of anthropogenic impact, is determined by the interaction of precipitation with the soil cover.
Surface stormwater runoff in the formation of contemporary urban surface deposited sediments
Authors: Seleznev Andrian , Yarmoshenko Ilia , Malinovsky Georgy , Kiseleva Daria , Ilgasheva Ekaterina , Ryanskaya Anastasia , Teterin Alexander
Published: June 2019

Surface runoff represents one of the major mechanism connecting sources, transport, deposition and storage of the particle matter in urban sediment cascade. The urban surface deposited sediment represents a medium for the transport and nonpoint source of pollution in cities. The study is aimed to characterize the role of surface stormwater runoff in accumulation of the contemporary surface deposited sediments in the urban environment taking to account the seasonal factor. The study was conducted on the example of residential area of Ekaterinburg, Russia. The role of the surface stormwater runoff in the formation of the urban surface deposited sediments was discussed. The snow and dirt mixture accumulates surface runoff and pollutants in it during the winter season in an urban area. A large supply of water accumulated in the snow cover during the cold period contributes to the formation of large volumes of snow-mud mixture during spring. The active snowmelt in the spring leads to the formation of snow-dirt sludge and transfer of the sedimentary material.
Infiltration and sedimentary brines of the Tunguska artesian basin and their chemical composition
Authors: Sidkina Evgeniya
Published: June 2019

The paper presents shortly characterized types of brines by origin. Brines of the Tunguska artesian basin are devided into the following types: infiltration, sedimentary and ancient infiltration ones. For this classification, the calculation of genetic coefficients was used. The relationships between the origin of brines and their salinity and chemical composition are shown.
Exponential trends in flowback chemistry from a hydraulically stimulated deep geothermal borehole in granite; Pohang, South Korea
Authors: Banks David , Burnside Neil , Westaway Rob , Zimmermann Günter , Hofmann Hannes
Published: June 2019

Samples of flowback water from a 4.3 km deep geothermal borehole in granite (Pohang, South Korea) were collected following a period of hydraulic stimulation by injection of surface water. Electrical conductivity, temperature and water chemistry of the flowback water were measured. To a first approximation, the data conform closely to a simple ‘mixing tank’ model, with an exponential trend between two end members: an initial injected surface water to a more brackish ‘resident groundwater’ composition. Significant deviation from the ‘mixing tank’ trend would be an indication of significant recent water-rock interaction or other anomalous factors. Such a deviation can tentatively be seen in Na+/Cl- data, especially between 88 and 200 m3 flowback (2.8 to 8.8 hr).