Recent Submissions

  • 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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  • Journal Article

    Semi-Automated Heavy-Mineral Analysis by Raman Spectroscopy 

    Lünsdorf; Kalies; Ahlers; Dunkl; von Eynatten
    Minerals 2019; 9(7): Art. 385
    A significant amount of information on sedimentary provenance is encoded in the heavy minerals of a sediment or sedimentary rock. This information is commonly assessed by optically determining the heavy-mineral assemblage, potentially followed by geochemical and/or geochronological analysis of specific heavy minerals. The proposed method of semi-automated heavy-mineral analysis by Raman spectroscopy (Raman-HMA) aims to combine the objective mineral identification capabilities of Raman spectroscopy with high-resolution geochemical techniques applied to single grains. The Raman-HMA method is an e cient and precise tool that significantly improves the comparability of heavy-mineral data with respect to both overall assemblages and individual compositions within solid solution series. Furthermore, the e ciency of subsequent analysis is increased due to identification and spatial referencing of the heavy minerals in the sample slide. The method is tested on modern sediments of the Fulda river (central Germany) draining two Miocene volcanic sources (Vogelsberg, Rhön) resting on top of Lower Triassic siliciclastic sediments. The downstream evolution of the volcanic detritus is documented and the capability to analyze silt-sized grains has revealed an additional eolian source. This capability also poses the possibility of systematically assessing the heavy-mineral assemblages of shales, which are often disregarded in sedimentary provenance studies.
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  • Journal Article

    Improving the Socioeconomic Status of Rural Women Associated with Agricultural Land Acquisition: A Case Study in Huong Thuy Town, Thua Thien Hue Province, Vietnam 

    Pham Thi, Nhung; Kappas, Martin; Faust, Heiko
    Land 2019; 8(10): Art. 151
    Since the 2000s, agricultural land acquisition (ALA) for urbanization and industrialization has been quickly implemented in Vietnam, which has led to a huge socioeconomic transformation in rural areas. This paper applies the sustainable livelihoods framework to analyze how ALA has impacted the socioeconomic status (SES) of rural women whose agricultural land was acquired. To get primary data, we surveyed 150 a ected households, conducted three group discussions and interviewed nine key informants. The research findings reveal that ALA, when applied toward urbanization, has significantly improved the occupational status of rural women by creating non-farm job opportunities that have improved their income, socioeconomic knowledge and working skills. While their SES has been noticeably enhanced, these positive impacts are still limited in cases where ALA is applied toward industrial and energy development, since these purposes do not create many new jobs. Moreover, the unclear responsibility of stakeholders and inadequate livelihood rehabilitation programs of ALA projects have obstructed the opportunities of rural women. To improve the SES of rural women, we recommend that ALA policy initiate a flexible livelihoods support plan based on the purpose of ALA and the concrete responsibilities of stakeholders and investors.
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  • Journal Article

    Making Rainwater Harvesting a Key Solution for Water Management: The Universality of the Kilimanjaro Concept 

    Qi, Qinwen; Marwa, Janeth; Mwamila, Tulinave Burton; Gwenzi, Willis; Noubactep, Chicgoua
    Sustainability 2019; 11(20): Art. 11205606
    Rainwater is conventionally perceived as an alternative drinking water source, mostly needed to meet water demand under particular circumstances, including under semi-arid conditions and on small islands. More recently, rainwater has been identified as a potential source of clean drinking water in cases where groundwater sources contain high concentrations of toxic geogenic contaminants. Specifically, this approach motivated the introduction of the Kilimanjaro Concept (KC) to supply fluoride-free water to the population of the East African Rift Valley (EARV). Clean harvested rainwater can either be used directly as a source of drinking water or blended with polluted natural water to meet drinking water guidelines. Current e orts towards the implementation of the KC in the EARV are demonstrating that harvesting rainwater is a potential universal solution to cover ever-increasing water demands while limiting adverse environmental impacts such as groundwater depletion and flooding. Indeed, all surface and subsurface water resources are replenished by precipitation (dew, hail, rain, and snow), with rainfall being the main source and major component of the hydrological cycle. Thus, rainwater harvesting systems entailing carefully harvesting, storing, and transporting rainwater are suitable solutions for water supply as long as rain falls on earth. Besides its direct use, rainwater can be infiltrating into the subsurface when and where it falls, thereby increasing aquifer recharge while minimizing soil erosion and limiting floods. The present paper presents an extension of the original KC by incorporating Chinese experience to demonstrate the universal applicability of the KC for water management, including the provision of clean water for decentralized communities.
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  • Journal Article

    Characterization of polycyclic aromatic hydrocarbons and their phenanthroperylene quinone precursors in fossil crinoids using liquid chromatography–atmospheric pressure photoionization mass spectrometry 

    Wolkenstein, Klaus
    Organic Geochemistry 2019; 136: Art. 103892
    The distribution and origin of diagenetic products of polycyclic quinone pigments in fossil crinoids was investigated using high-performance liquid chromatography–diode array detection–atmospheric pressure photoionization mass spectrometry (HPLC–DAD–APPI-MS). A number of characteristic higher-molecular-weight polycyclic aromatic hydrocarbons (PAHs) were identified in toluene extracts of diverse crinoid samples, with 1,2,3,4,5,6-hexahydrophenanthro[1,10,9,8-opqra]perylene as the main compound. Moreover, phenanthro[1,10,9,8-opqra]perylene-7,14-dione (PPQ) and further derivatives were detected for the first time in the fossil record, representing intermediates between hydroxylated phenanthroperylene quinone pigments such as fringelite F and phenanthroperylene PAHs. The widespread presence of PPQ, its derivatives and related PAHs in fossil crinoids which contain phenanthroperylene quinone pigments confirms the diagenetic formation of specific PAHs by reductive degradation of quinone pigments.
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  • Journal Article

    Organic signatures in Pleistocene cherts from Lake Magadi (Kenya) – implications for early Earth hydrothermal deposits 

    Reinhardt, Manuel; Goetz, Walter; Duda, Jan-Peter; Heim, Christine; Reitner, Joachim; Thiel, Volker
    Biogeosciences 2019; 16(12) p.2443-2465
    Organic matter in Archean hydrothermal cherts may provide an important archive for molecular traces of the earliest life on Earth. The geobiological interpretation of this archive, however, requires a sound understanding of organic matter preservation and alteration in hydrothermal systems. Here we report on organic matter (including molecular biosignatures) enclosed in hydrothermally influenced cherts of the Pleistocene Lake Magadi (Kenya; High Magadi Beds and Green Beds). The Magadi cherts contain low organic carbon (< 0.4 wt %) that occurs in the form of finely dispersed clots, layers, or encapsulated within microscopic carbonate rhombs. Both extractable (bitumen) and non-extractable organic matter (kerogen) were analyzed. The bitumens contain immature “biolipids” like glycerol mono- and diethers (e.g., archaeol and extended archaeol), fatty acids, and alcohols indicative for, inter alia, thermophilic cyanobacteria, sulfate reducers, and haloarchaea. However, co-occurring “geolipids” such as n-alkanes, hopanes, and polycyclic aromatic hydrocarbons (PAHs) indicate that a fraction of the bitumen has been thermally altered to early or peak oil window maturity. This more mature fraction likely originated from defunctionalization of dissolved organic matter and/or hydrothermal petroleum formation at places of higher thermal flux. Like the bitumens, the kerogens also show variations in thermal maturities, which can partly be explained by admixture of thermally pre-altered macromolecules. However, findings of archaea-derived isoprenoid moieties (C20 and C25 chains) in kerogen pyrolysates indicate rapid sequestration of some archaeal lipids into kerogen while hydrothermal alteration was active. We posit that such early sequestration may enhance the resistance of molecular biosignatures against in situ hydrothermal and post-depositional alteration. Furthermore, the co-occurrence of organic matter with different thermal maturities in the Lake Magadi cherts suggests that similar findings in Archean hydrothermal deposits could partly reflect original environmental conditions and not exclusively post-depositional overprint or contamination. Our results support the view that kerogen in Archean hydrothermal cherts may contain important information on early life. Our study also highlights the suitability of Lake Magadi as an analog system for hydrothermal chert environments on the Archean Earth.
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  • Journal Article

    Characterizing the Suitability of Granular Fe0 for the Water Treatment Industry 

    Hu, Rui; Cui, Xuesong; Xiao, Minhui; Qiu, Pengxiang; Lufingo, Mesia; Gwenzi, Willis; Noubactep, Chicgoua
    Processes 2019; 7(10): Art. 652
    here is a burgeoning interest in reliably characterizing the intrinsic reactivity of metallic iron materials (Fe0) or zero-valent iron materials (ZVI) used in the water treatment industry. The present work is a contribution to a science-based selection of Fe0 for water treatment. A total of eight (8) granular ZVI materials (ZVI1 to ZVI8) were tested. Fe0 dissolution in ethylenediaminetetraacetic acid (EDTA test) and 1,10-Phenanthroline (Phen test) is characterized in parallel experiments for up to 250 h (10 days). 50 mL of each solution and 0.1 g of each Fe0 material are equilibrated in quiescent batch experiments using 2 mM EDTA or Phen. Results indicated a far higher extent of iron dissolution in EDTA than in Phen under the experimental conditions. The tested materials could be grouped into three reactivity classes: (i) low (ZVI4, ZVI6, ZVI7, and ZVI8), (ii) moderate (ZVI1 and ZVI5) and (iii) high (ZVI2 and ZVI3). The order of reactivity was the same for both tests: ZVI2 ≅ ZVI3 > ZVI1 ≅ ZVI5 > ZVI4 ≅ ZVI6 ≅ ZVI7 ≅ ZVI8. Phen results revealed for the first time the time-dependent variation of the kinetics of iron corrosion (corrosion rate) in short-term batch experiments. Overall, the results demonstrated the superiority of the Phen test for evaluating the initial stage of Fe0 dissolution. Long-term column experiments are recommended to deepen the acquired knowledge.
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  • Journal Article

    Comparison of Satellite Soil Moisture Products in Mongolia and Their Relation to Grassland Condition 

    Vova, Oyudari; Kappas, Martin; Rafiei Emam, Ammar
    Land 2019; 8(9): Art. 142
    Monitoring of soil moisture dynamics provides valuable information about grassland degradation, since soil moisture directly affects vegetation cover. While the Mongolian soil moisture monitoring network is limited to the urban and protected natural areas, remote sensing data can be used to determine the soil moisture status elsewhere. In this paper, we determine whether in situ and remotely sensed data in the unaccounted areas of Southwestern Mongolia are consistent with each other, by comparing Soil Moisture and Ocean Salinity (SMOS) first passive L-band satellite data with in situ measurements. To evaluate the soil moisture products, we calculated the temporal, seasonal, and monthly average soil moisture content. We corrected the bias of SMOS soil moisture (SM) data using the in situ measured soil moisture with both the simple ratio and gamma methods. We verified the bias-corrected SMOS data with Nash–Sutcliffe method. The comparison results suggest that bias correction (of the simple ratio and gamma methods) enhances the reliability of the SMOS data, resulting in a higher correlation coefficient. We then examined the correlation between SMOS and Normalized Difference Vegetation Index (NDVI) index in the various ecosystems. Analysis of the SMOS and in situ measured soil moisture data revealed that spatial soil moisture distribution matches the rainfall events in Southwestern Mongolia for the period 2010 to 2015. The results illustrate that the bias-corrected, monthly-averaged SMOS data has a high correlation with the monthly-averaged NDVI (R2 > 0.81). Both NDVI and rainfall can be used as indicators for grassland monitoring in Mongolia. During 2015, we detected decreasing soil moisture in approximately 30% of the forest-steppe and steppe areas. We assume that the current ecosystem of land is changing rapidly from forest to steppe and also from steppe to desert. The rainfall rate is the most critical factor influencing the soil moisture storage capacity in this region. The collected SMOS data reflects in situ conditions, making it an option for grassland studies.
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  • Journal Article

    Bacterial succession along a sediment porewater gradient at Lake Neusiedl in Austria 

    von Hoyningen-Huene, Avril Jean Elisabeth; Schneider, Dominik; Fussmann, Dario; Reimer, Andreas; Arp, Gernot; Daniel, Rolf
    Scientific Data 2019; 6(1): Art. 163
    We provide bacterial 16S rRNA community and hydrochemical data from water and sediments of Lake Neusiedl, Austria. The sediments were retrieved at 5 cm intervals from 30-40 cm push cores. The lake water community was recovered by filtration through a 3.0/0.2 µm filter sandwich. For 16S rRNA gene amplicon-based community profiling, DNA was extracted from the sediment and filters and the bacterial V3-V4 regions were amplified and sequenced using a MiSeq instrument (Illumina). The reads were quality-filtered and processed using open source bioinformatic tools, such as PEAR, cutadapt and VSEARCH. The taxonomy was assigned against the SILVA SSU NR 132 database. The bacterial community structure was visualised in relation to water and porewater chemistry data. The bacterial community in the water column is distinct from the sediment. The most abundant phyla in the sediment shift from Proteobacteria to Chloroflexota (formerly Chloroflexi). Ammonium and total alkalinity increase while sulphate concentrations in the porewater decrease. The provided data are of interest for studies targeting biogeochemical cycling in lake sediments.
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