Recent Submissions

  • Journal Article

    The Preparation and Preliminary Characterisation of Three Synthetic Andesite Reference Glass Materials (ARM‐1, ARM‐2, ARM‐3) for In Situ Microanalysis 

    Wu, Shitou; Wörner, Gerhard; Jochum, Klaus Peter; Stoll, Brigitte; Simon, Klaus; Kronz, Andreas
    Geostandards and Geoanalytical Research 2019; 43(4) p.567-584
    Three synthetic reference glasses were prepared by directly fusing and stirring 3.8 kg of high-purity oxide powders to provide reference materials for microanalytical work. These glasses have andesitic major compositions and are doped with fifty-four trace elements in nearly identical abundance (500, 50, 5 µg g-1) using oxide powders or element solutions, and are named ARM-1, 2 and 3, respectively. We further document that sector-field (SF) ICP-MS (Element 2 or Element XR) is capable of sweeping seventy-seven isotopes (from 7Li to 238U, a total of sixty-eight elements) in 1 s and, thus, is able to quantify up to sixty-eight elements by laser sampling. Micro- and bulk analyses indicate that the glasses are homogeneous with respect to major and trace elements. This paper provides preliminary data for the ARM glasses using a variety of analytical techniques (EPMA, XRF, ICP-OES, ICP-MS, LA-Q-ICP-MS and LA-SF-ICP-MS) performed in ten laboratories. Discrepancies in the data of V, Cr, Ni and Tl exist, mainly caused by analytical limitations. Preliminary reference and information values for fifty-six elements were calculated with uncertainties [2 relative standard error (RSE)] estimated in the range of 1–20%.
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  • Journal Article

    OH defect contents in quartz in a granitic system at 1–5 kbar 

    Potrafke, Alexander; Stalder, Roland; Schmidt, Burkhard C.; Ludwig, Thomas
    Contributions to Mineralogy and Petrology 2019; 174(12)
    Quartz is able to incorporate trace elements (e.g., H, Li, Al, B) depending on the formation conditions (P, T, and chemical system). Consequently, quartz can be used as a tracer for petrogenetic information of silicic plutonic bodies. In this experimental study, we provide the first data set on the OH defect incorporation in quartz from granites over a pressure/temperature range realistic for the emplacement of granitic melts in the upper crust. Piston cylinder and internally heated pressure vessel synthesis experiments were performed in a water-saturated granitic system at 1-5 kbar and 700-950 °C. Crystals from successful runs were analysed by secondary ion mass spectrometry (SIMS) and Fourier transform infrared (FTIR) spectroscopy, and their homogeneity was verified by FTIR imaging. IR absorption bands can be assigned to specific OH defects and analysed qualitatively and quantitatively and reveal that (1) the AlOH band triplet at 3310, 3378 and 3430 cm-1 is the dominating absorption feature in all spectra, (2) no simple trend of total OH defect incorporation with pressure can be observed, (3) the LiOH defect band at 3470-3480 cm-1 increases strongly in a narrow pressure interval from 4 kbar (220 µg/g H2O) to 4.5 kbar (500 µg/g H2O), and declines equally strong towards 5 kbar (180 µg/g H2O). Proton incorporation is charge balanced according to the equation H+ + A+ + P5+ = M3+ + B3+, with A+ = alkali ions and M3+ = trivalent metal ions.
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  • Journal Article

    Quantifying a critical marl thickness for vertical fracture extension using field data and numerical experiments 

    Afşar, Filiz; Luijendijk, Elco
    Geoscience Frontiers 2019; 10(6) p.2135-2145
    In fractured reservoirs characterized by low matrix permeability, fracture networks control the main fluid flow paths. However, in layered reservoirs, the vertical extension of fractures is often restricted to single layers. In this study, we explored the effect of changing marl/shale thickness on fracture extension using comprehensive field data and numerical modeling. The field data were sampled from coastal exposures of Liassic limestone-marl/shale alternations in Wales and Somerset (Bristol Channel Basin, UK). The vertical fracture traces of more than 4000 fractures were mapped in detail. Six sections were selected to represent a variety of layer thicknesses. Besides the field data also thin sections were analyzed. Numerical models of fracture extension in a two-layer limestone-marl system were based on field data and laboratory measurements of Young's moduli. The modeled principal stress magnitude σ3 along the lithological contact was used as an indication for fracture extension through marls. Field data exhibit good correlation (R2 = 0.76) between fracture extension and marl thickness, the thicker the marl layer the fewer fractures propagate through. The model results show that almost no tensile stress reaches the top of the marl layer when the marls are thicker than 30 cm. For marls that are less than 20 cm, the propagation of stress is more dependent on the stiffness of the marls. The higher the contrast between limestone and marl stiffness the lower the stress that is transmitted into the marl layer. In both model experiments and field data the critical marl thickness for fracture extension is ca. 15–20 cm. This quantification of critical marl thicknesses can be used to improve predictions of fracture networks and permeability in layered rocks. Up- or downsampling methods often ignore spatially continuous impermeable layers with thicknesses that are under the detection limit of seismic data. However, ignoring these layers can lead to overestimates of the overall permeability. Therefore, the understanding of how fractures propagate and terminate through impermeable layers will help to improve the characterization of conventional reservoirs.
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  • Journal Article

    A Novel and Facile Method to Characterize the Suitability of Metallic Iron for Water Treatment 

    Lufingo, Mesia; Ndé-Tchoupé, Arnaud Igor; Hu, Rui; Njau, Karoli N.; Noubactep, Chicgoua
    Water 2019; 11(12): Art. 2465
    Metallic iron (Fe0) materials have been industrially used for water treatment since the 1850s. There are still many fundamental challenges in affordably and reliably characterizing the Fe0 intrinsic reactivity. From the available methods, the one using Fe0 dissolution in ethylenediaminetetraacetic acid (EDTA—2 mM) was demonstrated the most applicable as it uses only four affordable chemicals: Ascorbic acid, an ascorbate salt, EDTA and 1,10-Phenanthroline (Phen). A careful look at these chemicals reveals that EDTA and Phen are complexing agents for dissolved iron species. Fe3-EDTA is very stable and difficult to destabilize; ascorbic acid is one of the few appropriate reducing agents, therefore. On the other hand, the Fe2-Phen complex is so stable that oxidation by dissolved O2 is not possible. This article positively tests Fe0 (0.1 g) dissolution in 2 mM Phen (50 mL) as a characterization tool for the intrinsic reactivity, using 9 commercial steel wool (Fe0 SW) specimens as probe materials. The results are compared with those obtained by the EDTA method. The apparent iron dissolution rate in EDTA (kEDTA) and in Phen (kPhen) were such that 0.53 ≤ kEDTA (μg h−1) ≤ 4.81 and 0.07 ≤ kPhen (μg h−1) ≤ 1.30. Higher kEDTA values, relative to kPhen, are a reflection of disturbing Fe3 species originating from Fe2 oxidation by dissolved O2 and dissolution of iron corrosion products. It appears that the Phen method considers only the forward dissolution of Fe0. The Phen method is reliable and represents the most affordable approach for characterizing the suitability of Fe0 for water treatment.
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  • Journal Article

    OH in detrital quartz grains as tool for provenance analysis: Case studies on various settings from Cambrian to Recent 

    Stalder, Roland; von Eynatten, Hilmar; Costamoling, Julian; Potrafke, Alexander; Dunkl, István; Meinhold, Guido
    Sedimentary Geology 2019; 389 p.121-126
    Detrital quartz grains from Paleozoic and Mesozoic sandstones from North Africa and central Europe, respectively, and from recent siliciclastic sediments of the Elbe River from Germany were analysed by IR spectroscopy with respect to their OH defect content. Sample sets were carefully chosen to cover different stratigraphic units fromdifferent localities and according to previous findings that indicate a significant change in the source region in the respective sedimentary system. The validity of the new method is compared to heavy mineral and zircon age spectra analysis from previous studies. Results reveal that the OH defect inventory in quartz shows in all investigated sedimentary successions significant internal variations from sample to sample and thus may be used as a tool to identify changes in the source region. The degree of changes observedwith the new method does not necessarily reflect the magnitude in differences observed by other methods (such as heavy minerals and/or zircon age spectra), underlining the potential as complementary tool for provenance analysis. The new tool is also tested to estimate mixing proportions between the Variscan and the Scandinavian signal in the Elbe River, resulting in a surprisingly high contribution of the Nordic source.
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  • Journal Article

    Precipitation of dolomite from seawater on a Carnian coastal plain (Dolomites, northern Italy): evidence from carbonate petrography and Sr isotopes 

    Rieder, Maximilian; Wegner, Wencke; Horschinegg, Monika; Klackl, Stefanie; Preto, Nereo; Breda, Anna; Gier, Susanne; Klötzli, Urs; Bernasconi, Stefano M.; Arp, Gernot; et al.
    Meister, Patrick
    Solid Earth 2019; 10(4) p.1243-1267
    The geochemical conditions conducive to dolomite formation in shallow evaporitic environments along the Triassic Tethyan margin are still poorly understood. Large parts of the Triassic dolomites in the Austroalpine and the southern Alpine realm are affected by late diagenetic or hydrothermal overprinting, but recent studies from the Carnian Travenanzes Formation (southern Alps) provide evidence of primary dolomite. Here a petrographic and geochemical study of dolomites intercalated in a 100 m thick Carnian sequence of distal alluvial plain deposits is presented to gain better insight into the conditions and processes of dolomite formation. The dolomites occur as 10 to 50 cm thick homogeneous beds, millimetre-scale laminated beds, and nodules associated with palaeosols. The dolomite is nearly stoichiometric with slightly attenuated ordering reflections. Sedimentary structures indicate that the initial primary dolomite or precursor phase consisted largely of unlithified mud. Strontium isotope ratios (87Sr∕86Sr) of homogeneous and laminated dolomites reflect Triassic seawater composition, suggesting precipitation in evaporating seawater in a coastal ephemeral lake or sabkha system. However, the setting differed from modern sabkha or coastal ephemeral lake systems by being exposed to seasonally wet conditions with significant siliciclastic input and the inhibition of significant lateral groundwater flow by impermeable clay deposits. Thus, the ancient Tethyan margin was different from modern analogues of primary dolomite formation.
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  • Journal Article

    Redirecting Research on Fe0 for Environmental Remediation: The Search for Synergy 

    Hu, Rui; Noubactep, Chicgoua
    International Journal of Environmental Research and Public Health 2019; 16(22): Art. 4465
    A survey of the literature on using metallic iron (Fe0) for environmental remediation suggests that the time is ripe to center research on the basic relationship between iron corrosion and contaminant removal. This communication identifies the main problem, which is based on the consideration that contaminant reductive transformation is the cathodic reaction of iron oxidative dissolution. Properly considering the inherent complexities of the Fe0/H2O system will favor an appropriate research design that will enable more e cient and sustainable remediation systems. Successful applications of Fe0/H2O systems require the collective consideration of progress achieved in understanding these systems. More e orts should be made to decipher the long-term kinetics of iron corrosion, so as to provide better approaches to accurately predict the performance of the next generation Fe0-based water treatment systems.
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  • Journal Article

    A Chiral Gas–Hydrate Structure Common to the Carbon Dioxide–Water and Hydrogen–Water Systems 

    Amos, Daniel M.; Donnelly, Mary-Ellen; Teeratchanan, Pattanasak; Bull, Craig L.; Falenty, Andrzej; Kuhs, Werner F.; Hermann, Andreas; Loveday, John S.
    The Journal of Physical Chemistry Letters 2017; 8(17) p.4295-4299
    We present full in situ structural solutions of carbon dioxide hydrate-II and hydrogen hydrate C0 at elevated pressures using neutron and X-ray diffraction. We find both hydrates adopt a common water network structure. The structure exhibits several features not previously found in hydrates; most notably it is chiral and has large open spiral channels along which the guest molecules are free to move. It has a network that is unrelated to any experimentally known ice, silica, or zeolite network but is instead related to two Zintl compounds. Both hydrates are found to be stable in electronic structure calculations, with hydration ratios in very good agreement with experiment.
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  • Journal Article

    Environmental Governance Meets Reality: A Micro-Scale Perspective on Sustainability Certification Schemes for Oil Palm Smallholders in Jambi, Sumatra 

    Martens, Katrin; Kunz, Yvonne; Rosyani, Ir.; Faust, Heiko
    Society & Natural Resources p.1-17
    Multi-stakeholder sustainability certification schemes have become a favorite instrument for applying good governance, though studies indicate their inefficiency at the producer level. In this study, we used a mixed-method approach to first, map the institutional context of independent oil-palm smallholders in rural Sumatra while, second, reflecting upon the impact of the Smallholder Standard proposed by the Roundtable on Sustainable Palm Oil on smallholder management practices. We hold that non-recognition of micro-scale perspectives within governance processes may partially explain noncompliance with certification principles among smallholders. The Smallholder Standard appears unable to mitigate challenges important for smallholders, who in turn cannot properly comply with it, due to problems including weather instability and high management costs. We suggest that certification schemes need to work on some overlooked but essential preconditions of good governance, namely gaining micro-level visibility and acceptance.
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  • Journal Article

    Texture Development of Clay‐Rich Sediments Across the Costa Rica Subduction Zone 

    Kuehn, Rebecca; Stipp, Michael; Leiss, Bernd
    Journal of Geophysical Research: Solid Earth p.7756-7770
    During sedimentation, burial, and deformation at active continental margins, clay‐rich sediments develop crystallographic preferred orientations (textures) due to the progressive alignment of phyllosilicates. Such textures help to interpret sedimentation and compaction conditions as well as tectonic processes at convergent margins. At the Costa Rica Trench, subduction and plate boundary deformation between the downgoing oceanic Cocos Plate and the overriding Caribbean Plate was investigated during Integrated Ocean Drilling Program Expeditions 334 and 344 within the Costa Rica Seismogenesis Project. Samples of varying depths from the Cocos Plate, the frontal prism, and the slope of the Caribbean Plate were analyzed regarding their composition and texture. Composition is quite similar for all sample locations of the hemipelagic section across the trench as determined by X‐ray powder analysis. Texture analysis reveals that phyllosilicates in samples from the incoming plate show in general weaker textures than those from upper and middle slope of the overriding plate. Samples from the frontal accretionary prism, however, mostly correspond to the incoming plate fabric according to their oceanic origin. Texture intensity depends on the internal parameters grain size and shape, porosity, and composition as well as compaction and tectonics. In samples from the continental wedge and the frontal accretionary prism, we are able to distinguish tectonically undisturbed compacted sediments from core sections that suffered faulting and folding due to subduction‐related deformation. This helps to constrain a more detailed image of sedimentary compaction and localized as well as distributed deformation across the active continental margin offshore Costa Rica.
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  • Journal Article

    Timing and origin of natural gas accumulation in the Siljan impact structure, Sweden 

    Drake, Henrik; Roberts, Nick M. W.; Heim, Christine; Whitehouse, Martin J.; Siljeström, Sandra; Kooijman, Ellen; Broman, Curt; Ivarsson, Magnus; Åström, Mats E.
    Nature Communications 2019; 10(1)
    Fractured rocks of impact craters may be suitable hosts for deep microbial communities on Earth and potentially other terrestrial planets, yet direct evidence remains elusive. Here, we present a study of the largest crater of Europe, the Devonian Siljan structure, showing that impact structures can be important unexplored hosts for long-term deep microbial activity. Secondary carbonate minerals dated to 80 ± 5 to 22 ± 3 million years, and thus postdating the impact by more than 300 million years, have isotopic signatures revealing both microbial methanogenesis and anaerobic oxidation of methane in the bedrock. Hydrocarbons mobilized from matured shale source rocks were utilized by subsurface microorganisms, leading to accumulation of microbial methane mixed with a thermogenic and possibly a minor abiotic gas fraction beneath a sedimentary cap rock at the crater rim. These new insights into crater hosted gas accumulation and microbial activity have implications for understanding the astrobiological consequences of impacts.
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  • Journal Article

    Influence of Drone Altitude, Image Overlap, and Optical Sensor Resolution on Multi-View Reconstruction of Forest Images 

    Seifert, Erich; Seifert, Stefan; Vogt, Holger; Drew, David; van Aardt, Jan; Kunneke, Anton; Seifert, Thomas
    Remote Sensing 2019; 11(10): Art. 1252
    Recent technical advances in drones make them increasingly relevant and important tools for forest measurements. However, information on how to optimally set flight parameters and choose sensor resolution is lagging behind the technical developments. Our study aims to address this gap, exploring the effects of drone flight parameters (altitude, image overlap, and sensor resolution) on image reconstruction and successful 3D point extraction. This study was conducted using video footage obtained from flights at several altitudes, sampled for images at varying frequencies to obtain forward overlap ratios ranging between 91 and 99%. Artificial reduction of image resolution was used to simulate sensor resolutions between 0.3 and 8.3 Megapixels (Mpx). The resulting data matrix was analysed using commercial multi-view reconstruction (MVG) software to understand the effects of drone variables on (1) reconstruction detail and precision, (2) flight times of the drone, and (3) reconstruction times during data processing. The correlations between variables were statistically analysed with a multivariate generalised additive model (GAM), based on a tensor spline smoother to construct response surfaces. Flight time was linearly related to altitude, while processing time was mainly influenced by altitude and forward overlap, which in turn changed the number of images processed. Low flight altitudes yielded the highest reconstruction details and best precision, particularly in combination with high image overlaps. Interestingly, this effect was nonlinear and not directly related to increased sensor resolution at higher altitudes. We suggest that image geometry and high image frequency enable the MVG algorithm to identify more points on the silhouettes of tree crowns. Our results are some of the first estimates of reasonable value ranges for flight parameter selection for forestry applications.
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  • Journal Article

    Ecosystem services of a functionally diverse riparian zone in the Amazon–Cerrado agricultural frontier 

    Nóbrega, Rodolfo L. B.; Ziembowicz, Taciana; Torres, Gilmar N.; Guzha, Alphonce C.; Amorim, Ricardo S. S.; Cardoso, Domingos; Johnson, Mark S.; Santos, Túlio G.; Couto, Eduardo; Gerold, Gerhard
    Global Ecology and Conservation 2020; 21: Art. e00819
    The ecological services provided by protected riparian zones in human-altered landscapes are widely acknowledged, yet little is known about them. In this study, we assess ecosystem properties that a protected riparian zone maintains in contrast to environmental changes in its surroundings caused by agro-industrial activities in the northwestern fringe of the Brazilian Cerrado on the Amazon–Cerrado agricultural frontier. We assessed the plant biodiversity, soil hydro-physical properties, and water quality, to understand how the underlying ecological characteristics of a riparian zone withstand the effects of its neighboring cropland area on the stream water quality. We show that the riparian zone is fundamental in providing key ecosystem regulating services, including maintenance of plant biodiversity, soil properties, and water quality. Protection of plant biodiversity in the riparian zone sustains a synergy between soil, and functionally and phylogenetically diverse plant communities by promoting higher infiltration rates, higher soil porosity, and natural soil biogeochemistry conditions, which in turn have direct implications for stream water quality. Our study reaffirms that the conservation of riparian zones is crucial to buffer the negative impacts of agricultural practices on ecosystem services. Our results provide consistent evidence to support further studies and environmental policies for riparian environments, which are often the last fragment of natural vegetation remaining in the dominantly agricultural lands within the Cerrado and Amazon forests.
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  • Journal Article

    Beo v1.0: numerical model of heat flow and low-temperature thermochronology in hydrothermal systems 

    Luijendijk, Elco
    Geoscientific Model Development 2019; 12(9) p.4061-4073
    Low-temperature thermochronology can provide records of the thermal history of the upper crust and can be a valuable tool to quantify the history of hydrothermal systems. However, existing model codes of heat flow around hydrothermal systems do not include low-temperature thermochronometer age predictions. Here I present a new model code that simulates thermal history around hydrothermal systems on geological timescales. The modelled thermal histories are used to calculate apatite (U–Th)∕He (AHe) ages, which is a thermochronometer that is sensitive to temperatures up to 70 ∘C. The modelled AHe ages can be compared to measured values in surface outcrops or borehole samples to quantify the history of hydrothermal activity. Heat flux at the land surface is based on equations of latent and sensible heat flux, which allows more realistic land surface and spring temperatures than models that use simplified boundary conditions. Instead of simulating fully coupled fluid and heat flow, the code only simulates advective and conductive heat flow, with the rate of advective fluid flux specified by the user. This relatively simple setup is computationally efficient and allows running larger numbers of models to quantify model sensitivity and uncertainty. Example case studies demonstrate the sensitivity of hot spring temperatures to the depth, width and angle of permeable fault zones, and the effect of hydrothermal activity on AHe ages in surface outcrops and at depth.
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  • Journal Article

    Tissue-specific evaluation of suitable reference genes for RT-qPCR in the pond snail, Lymnaea stagnalis 

    Young, Alexander P.; Landry, Carmen F.; Jackson, Daniel J.; Wyeth, Russell C.
    PeerJ 2019; 7: Art. e7888
    Reverse transcription quantitative PCR (RT-qPCR) is a robust technique for the quantification and comparison of gene expression. To obtain reliable results with this method, one or more reference genes must be employed to normalize expression measurements among treatments or tissue samples. Candidate reference genes must be validated to ensure that they are stable prior to use in qPCR experiments. The pond snail (Lymnaea stagnalis) is a common research organism, particularly in the areas of learning and memory, and is an emerging model for the study of biological asymmetry, biomineralization, and evolution and development. However, no systematic assessment of qPCR reference genes has been performed in this animal. Therefore, the aim of our research was to identify stable reference genes to normalize gene expression data from several commonly studied tissues in L. stagnalis as well as across the entire body. We evaluated a panel of seven reference genes across six different tissues in L. stagnalis with RT-qPCR. The genes included: elongation factor 1-alpha, glyceraldehyde-3-phosphate dehydrogenase, beta-actin, beta-tubulin, ubiquitin, prenylated rab acceptor protein 1, and a voltage gated potassium channel. These genes exhibited a wide range of expression levels among tissues. The tissue-specific stability of each of the genes was consistent when measured by the standard stability assessment algorithms: geNorm, NormFinder, BestKeeper, and RefFinder. Our data indicate that the most stable reference genes vary among the tissues that we examined (central nervous system, tentacles, lips, penis, foot, mantle). Our results were generally congruent with those obtained from similar studies in other molluscs. Given that a minimum of two reference genes are recommended for data normalization, we provide suggestions for strong pairs of reference genes for single- and multi-tissue analyses of RT-qPCR data in L. stagnalis.
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  • Journal Article

    Water Treatment Using Metallic Iron: A Tutorial Review 

    Hu; Gwenzi; Sipowo-Tala; Noubactep
    Processes 2019; 7(9): Art. 622
    Researchers and engineers using metallic iron (Fe0) for water treatment need a tutorial review on the operating mode of the Fe0/H2O system. There are few review articles attempting to present systematic information to guide proper material selection and application conditions. However, they are full of conflicting reports. This review seeks to: (i) Summarize the state-of-the-art knowledge on the remediation Fe0/H2Osystem, (ii) discuss relevant contaminant removal mechanisms, and (iii) provide solutions for practical engineering application of Fe0-based systems for water treatment. Specifically, the following aspects are summarized and discussed in detail: (i) Fe0 intrinsic reactivity and material selection, (ii) main abiotic contaminant removal mechanisms, and (iii) relevance of biological and bio-chemical processes in the Fe0/H2O system. In addition, challenges for the design of the next generation Fe0/H2O systems are discussed. This paper serves as a handout to enable better practical engineering applications for environmental remediation using Fe0.
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  • Journal Article

    Organically-preserved multicellular eukaryote from the early Ediacaran Nyborg Formation, Arctic Norway 

    Agić, Heda; Högström, Anette E. S.; Moczydłowska, Małgorzata; Jensen, Sören; Palacios, Teodoro; Meinhold, Guido; Ebbestad, Jan Ove R.; Taylor, Wendy L.; Høyberget, Magne
    Scientific Reports 2019; 9(1)
    Eukaryotic multicellularity originated in the Mesoproterozoic Era and evolved multiple times since, yet early multicellular fossils are scarce until the terminal Neoproterozoic and often restricted to cases of exceptional preservation. Here we describe unusual organically-preserved fossils from mudrocks, that provide support for the presence of organisms with differentiated cells (potentially an epithelial layer) in the late Neoproterozoic. Cyathinema digermulense gen. et sp. nov. from the Nyborg Formation, Vestertana Group, Digermulen Peninsula in Arctic Norway, is a new carbonaceous organ-taxon which consists of stacked tubes with cup-shaped ends. It represents parts of a larger organism (multicellular eukaryote or a colony), likely with greater preservation potential than its other elements. Arrangement of open-ended tubes invites comparison with cells of an epithelial layer present in a variety of eukaryotic clades. This tissue may have benefitted the organism in: avoiding overgrowth, limiting fouling, reproduction, or water filtration. C. digermulense shares characteristics with extant and fossil groups including red algae and their fossils, demosponge larvae and putative sponge fossils, colonial protists, and nematophytes. Regardless of its precise affinity, C. digermulense was a complex and likely benthic marine eukaryote exhibiting cellular differentiation, and a rare occurrence of early multicellularity outside of Konservat-Lagerstätten.
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  • Journal Article

    Quantitation of eumelanin and pheomelanin markers in diverse biological samples by HPLC-UV-MS following solid-phase extraction 

    Affenzeller, Susanne; Frauendorf, Holm; Licha, Tobias; Jackson, Daniel J.; Wolkenstein, Klaus
    PLOS ONE 2019; 14(10): Art. e0223552
    Eumelanin and pheomelanin are well known and common pigments found in nature. However, their complex polymer structure and high thermostability complicate their direct chemical identification. A widely used analytical method is indirect determination using HPLC with UV detection of both types of melanin by their most abundant oxidation products: pyrrole-2,3-dicarboxylic acid (PDCA), pyrrole-2,3,5-tricarboxylic acid (PTCA), thiazole-4,5-dicarboxylic acid (TDCA), and thiazole-2,4,5-tricarboxylic acid (TTCA). An increasing interest in pigmentation in biological research led us to develop a highly sensitive and selective method to identify and quantify these melanin markers in diverse biological samples with complex matrices. By introducing solid-phase extraction (SPE, reversed-phase) following alkaline oxidation we could significantly decrease background signals while maintaining recoveries greater than 70%. Our HPLC-UV-MS method allows for confident peak identification via exact mass information in corresponding UV signals used for quantitation. In addition to synthetic melanin and Sepia officinalis ink as reference compounds eumelanin markers were detected in brown human hair and a brown bivalve shell (Mytilus edulis). Brown feathers from the common chicken (Gallus g. domesticus) yielded all four eumelanin and pheomelanin markers. The present method can be easily adapted for a wide range of future studies on biological samples with unknown melanin content.
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  • Journal Article

    Relationships between feeding and microbial faeces indices in dairy cows at different milk yield levels 

    Meyer, Stephanie; Thiel, Volker; Joergensen, Rainer Georg; Sundrum, Albert
    PLOS ONE 2019; 14(8): Art. e0221266
    A study was carried out to gain quantitative information on the diet-dependent faecal microbial biomass of dairy cows, especially on the biomass fractions of fungi, Gram-positive (G+) and Gram-negative (G-) bacteria. Groups of high-yield, low-yield and non-lactating cows were investigated at four different farms. A mean faecal microbial biomass C (MBC) concentration of 33.5 mg g-1 DM was obtained by the chloroform fumigation extraction method. This is similar to a mean microbial C concentration of 31.8 mg g-1 DM, which is the sum of bacterial C and fungal C, estimated by cell-wall derived muramic acid (MurN) and fungal glucosamine (GlcN), respectively. However, the response of these two approaches to the feeding regime was contradictory, due to feeding effects on the conversion values. The higher neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations in the non-lactating group led to higher (P < 0.05) concentrations of cellulose and lignin in their faeces in comparison with the lactating cows. This change in faecal chemical composition in the non-lactating group was accompanied by usually higher ratios of G+/G- phospholipid fatty acids (PLFA), ergosterol/MBC and fungal C/bacterial C. Although bacteria dominate the faecal microbial biomass, fungi contribute a considerable mean percentage of roughly 20% to the faecal microbiome, according to PLFA and amino sugar data, which requires more attention in the future. Near-infra red spectroscopic estimates of organic N and C fractions of cow faeces were able to model microbial biomarkers successfully, which might be useful in the future to predict its N2O emission potential and fertilizer value.
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  • Journal Article

    Constitutive Laws for Etnean Basement and Edifice Lithologies 

    Bakker, Richard R.; Violay, Marie E. S.; Vinciguerra, Sergio; Fazio, Marco; Benson, Philip M.
    Journal of Geophysical Research: Solid Earth
    Abstract The mechanical dynamics of volcanic systems can be better understood with detailed knowledge on strength of a volcanic edifice and subsurface. Previous work highlighting this on Mt. Etna has suggested that its carbonate basement could be a significant zone of widespread planar weakness. Here, we report new deformation experiments to better quantify such effects. We measure and compare key deformation parameters using Etna basalt, which is representative of upper edifice lava flows, and Comiso limestone, which is representative of the carbonate basement, under upper crustal conditions. These data are then used to derive empirical constitutive equations describing changes in rocks strength with pressure, temperature, and strain rate. At a constant strain rate of 10‐5 s‐1 and an applied confining pressure of 50 MPa, the brittle‐to‐ductile transitions were observed at 975 °C (Etna basalt) and 350 °C (Comiso limestone). For the basaltic edifice of Mt. Etna, the strength is described with a Mohr‐Coulomb failure criterion with μ ~ 0.704, C = 20 MPa. For the carbonate basement, strength is best described by a power law‐type flow in two regimes: a low‐T regime with stress exponent n ~ 5.4 and an activation energy Q ~ 170.6 kJ/mol and a high‐T regime with n ~ 2.4 and Q ~ 293.4 kJ/mol. We show that extrapolation of these data to Etna's basement predicts a brittle‐to‐ductile transition that corresponds well with the generally observed trends of the seismogenic zone underneath Mt. Etna. This in turn may be useful for future numerical simulations of volcano‐tectonic deformation of Mt. Etna, and other volcanoes with limestone basements. Plain Language Summary To be able to understand the deformation of volcanoes, such as ground movement and risks of flank collapse, we need to know under what conditions (temperature, stress, and overburden) the rocks either bend (flow) or break inside the volcano. Here we focus on Mt. Etna and study rocks from the edifice (basalt) and the rocks that the volcano is built upon (limestone that crops out at the surface at the town of Comiso, South East Sicily, Italy). We take the rocks to the laboratory where we deform the rocks under various temperature, confining pressure (to simulate overburden) and deformation rates. We then use the laboratory data to build up equations that can be used to figure out how the rocks behave underneath the volcano, at high temperatures and natural deformation speeds (which are a lot slower than in the lab). We check if our equations compare well to natural behavior by comparing with field data (earthquakes), which only happens when rocks break or slide along a fault plane, and not when the rocks are flowing. The equations may be used as input for future studies on the deformation of the volcano
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