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  • 1
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    Unveiling the wasp-waist structure of the Falkland shelf ecosystem: the role of Doryteuthis gahi as a keystone species and its trophic influences (2024)
    Cambridge University Press
    Details
    Publication Date: 2024-03-08
    Description: The Falkland Shelf is a highly productive ecosystem in the Southwest Atlantic Ocean. It is characterized by upwelling oceanographic dynamics and displays a wasp-waist structure, with few intermediate trophic-level species and many top predators that migrate on the shelf for feeding. One of these resident intermediate trophic-level species, the Patagonian longfin-squid Doryteuthis gahi, is abundant and plays an important role in the ecosystem. We used two methods to estimate the trophic structure of the Falkland Shelf food web, focusing on the trophic niche of D. gahi and its impacts on other species and functional groups to highlight the importance of D. gahi in the ecosystem. First, stable isotope measurements served to calculate trophic levels based on an established nitrogen baseline. Second, an Ecopath model was built to corroborate trophic levels derived from stable isotopes and inform about trophic interactions of D. gahi with other functional groups. The results of both methods placed D. gahi in the centre of the ecosystem with a trophic level of ∼ 3. The Ecopath model predicted high impacts and therefore a high keystoneness for both seasonal cohorts of D. gahi. Our results show that the Falkland Shelf is not only controlled by species feeding at the top and the bottom of the trophic chain. The importance of species feeding at the third trophic level (e.g. D. gahi and Patagonotothen ramsayi) and observed architecture of energy flows confirm the ecosystem's wasp-waist structure with middle-out control mechanisms at play.
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  • 2
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    The Impact of the Culture Regime on the Metabolome and Anti-Phytopathogenic Activity of Marine Fungal Co-Cultures (2024)
    MDPI
    Details
    Publication Date: 2024-03-15
    Description: Co-cultivation, coupled with the OSMAC approach, is considered an efficient method for expanding microbial chemical diversity through the activation of cryptic biosynthetic gene clusters (BGCs). As part of our project aiming to discover new fungal metabolites for crop protection, we previously reported five polyketides, the macrolides dendrodolides E (1) and N (2), the azaphilones spiciferinone (3) and 8α-hydroxy-spiciferinone (4), and the bis-naphtho-γ-pyrone cephalochromin (5) from the solid Potato Dextrose Agar (PDA) co-culture of two marine sediment-derived fungi, Plenodomus influorescens and Pyrenochaeta nobilis. However, some of the purified metabolites could not be tested due to their minute quantities. Here we cultivated these fungi (both axenic and co-cultures) in liquid regime using three different media, Potato Dextrose Broth (PDB), Sabouraud Dextrose Broth (SDB), and Czapek-Dox Broth (CDB), with or without shaking. The aim was to determine the most ideal co-cultivation conditions to enhance the titers of the previously isolated compounds and to produce extracts with stronger anti-phytopathogenic activity as a basis for future upscaled fermentation. Comparative metabolomics by UPLC-MS/MS-based molecular networking and manual dereplication was employed for chemical profiling and compound annotations. Liquid co-cultivation in PDB under shaking led to the strongest activity against the phytopathogen Phytophthora infestans. Except for compound 1, all target compounds were detected in the co-culture in PDB. Compounds 2 and 5 were produced in lower titers, whereas the azaphilones (3 and 4) were overexpressed in PDB compared to PDA. Notably, liquid PDB co-cultures contained meroterpenoids and depside clusters that were absent in the solid PDA co-cultures. This study demonstrates the importance of culture regime in BGC regulation and chemical diversity of fungal strains in co-culture studies.
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  • 3
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    Boreal (Eemian) Transgression in the Northeastern White Sea Region: Multiproxy Evidence from Bychye-2 Section (2024)
    MDPI
    Details
    Publication Date: 2024-04-09
    Description: Reconstructing interglacial marine environments helps us understand the climate change mechanisms of the past. To contribute to this body of knowledge, we studied a high-resolution 455 cm-thick sediment sequence of the Boreal (Eemian) marine beds directly overlying Moscovian (Saalian) moraine in the Bychye-2 section on the Pyoza River. We analyzed lithological and microfossil (foraminifers, ostracods, pollen, aquatic palynomorphs) variations at the studied site. Stratigraphical zonation is based on the local and well-established regional pollen zones, correlated with the western European pollen zones. The studied marine beds accumulated from the end of the Moscovian glacial (〉131 ka) until ca. 119.5 ka. We distinguished three successive phases: a seasonally sea-ice-covered, relatively deep, freshened basin in the initial rapid flooding stage (〉131–130.5 ka); a deep basin in the maximum flooding phase with less extensive sea ice cover (130.5–130.25 ka); and a shallow basin with reduced sea ice cover (130.25–119.5 ka). According to a pollen zone comparison with other sites, the regional glacioisostatic rebound started ca. 130 ka. The diverse warm-water assemblages of benthic foraminifers and ostracods containing typical Baltic Sea species occurred during the regression, mainly 128–124 ka, thus giving evidence for a relatively long-lasting connection between the White and Baltic Seas.
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  • 4
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    Screening Disinfection Byproducts in Arid-Coastal Wastewater: A Workflow Using GC×GC-TOFMS, Passive Sampling, and NMF Deconvolution Algorithm (2024)
    MDPI
    Details
    Publication Date: 2024-05-02
    Description: Disinfection during tertiary municipal wastewater treatment is a necessary step to control the spread of pathogens; unfortunately, it also gives rise to numerous disinfection byproducts (DBPs), only a few of which are regulated because of the analytical challenges associated with the vast number of potential DBPs. This study utilized polydimethylsiloxane (PDMS) passive samplers, comprehensive two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOFMS), and non-negative matrix factorization (NMF) spectral deconvolution for suspect screening of DBPs in treated wastewater. PDMS samplers were deployed upstream and downstream of the chlorination unit in a municipal wastewater treatment plant located in Abu Dhabi, and their extracts were analyzed using GC×GC-TOFMS. A workflow incorporating a multi-tiered, eight-filter screening process was developed, which successfully enabled the reliable isolation of 22 candidate DBPs from thousands of peaks. The NMF spectral deconvolution improved the match factor score of unknown mass spectra to the reference mass spectra available in the NIST library by 17% and facilitated the identification of seven additional DBPs. The close match of the first-dimension retention index data and the GC×GC elution patterns of DBPs, both predicted using the Abraham solvation model, with their respective experimental counterparts—with the measured data available in the NIST WebBook and the GC×GC elution patterns being those observed for the candidate peaks—significantly enhanced the accuracy of peak assignment. Isotopic pattern analysis revealed a close correspondence for 11 DBPs with clearly visible isotopologues in reference spectra, thereby further strengthening the confidence in the peak assignment of these DBPs. Brominated analogues were prevalent among the detected DBPs, possibly due to seawater intrusion. The fate, behavior, persistence, and toxicity of tentatively identified DBPs were assessed using EPI Suite™ and the CompTox Chemicals Dashboard. This revealed their significant toxicity to aquatic organisms, including developmental, mutagenic, and endocrine-disrupting effects in certain DBPs. Some DBPs also showed activity in various CompTox bioassays, implicating them in adverse molecular pathways. Additionally, 11 DBPs demonstrated high environmental persistence and resistance to biodegradation. This combined approach offers a powerful tool for future research and environmental monitoring, enabling accurate identification and assessment of DBPs and their potential risks.
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  • 5
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    Tracing the Origin and Magmatic Evolution of the Rejuvenated Volcanism in Santa Clara Island, Juan Fernández Ridge, SE Pacific (2024)
    MDPI
    Details
    Publication Date: 2024-06-12
    Description: Oceanic intraplate volcanoes sometimes experience late-stage eruptive activity known as rejuvenated volcanism, and contrasting interpretations for its petrogenesis depend on the compositional characteristics. In the Juan Fernández Ridge (JFR), a volcanic chain approximately 800 km in length emplaced on the Nazca Plate, some subaerial occurrences of rejuvenated volcanism have been recognized on the Robinson Crusoe and Santa Clara Islands, both part of the same deeply eroded shield volcano complex. This study aims to understand the origin and magmatic evolution of rejuvenated volcanism on Santa Clara Island, emplaced after ~2.15 Ma of quiescence above the shield sequence, mainly via the analysis of unpublished geochemical and isotopic data. Field reconnaissance identified two nearly coeval rejuvenated sequences on Santa Clara Island: Bahía W (BW) and Morro Spartan (MS), both formed by basanitic and picro-basaltic lava flows with brecciated levels and local intercalations of sedimentary and pyroclastic deposits. In comparison to the chemical signature of the preceding shield-building stage (comprised mainly of basalts and picrites), the two rejuvenated sequences exhibit a notable enrichment in incompatible elements, but the Sr, Nd, and Pb isotopes are very similar to the FOZO mantle endmember, with an apparent additional contribution of HIMU and EM1 components. The geochemistry of lavas revealed the involvement of various processes, including contamination by ultramafic xenoliths, high-pressure fractional crystallization of olivine and clinopyroxene, and potential partial assimilation of oceanic lithospheric components. While the oceanic lithosphere has been considered as a potential source, the isotopic data from Santa Clara lies outside of the mixing curve between depleted mantle (DM, here represented by the North Chile Rise and the East Pacific Rise) and the previous shield stage, suggesting that a lithospheric mantle is not the primary source for the rejuvenated stage volcanism. Therefore, we favor an origin of the rejuvenated volcanism from the mantle plume forming the JFR, supported by similarities in isotopic signatures with the shield stage and high values of 208Pb/204Pb (only comparable to San Félix—San Ambrosio in the vicinity of JFR), implying the presence of a regional source with radiogenic 208Pb/204Pb isotope ratios. In addition, isotopic variations are subparallel to the mixing line between HIMU and EM1 components, whose participation in different proportions might explain the observed trends. In conclusion, we propose that the source of the rejuvenated volcanism on Santa Clara Island is a heterogeneous mantle plume, the same one that fed the shield stage. The rejuvenated volcanism is derived from a secondary melting zone away from the main axis of the plume.
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  • 6
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    Representative Dynamic Accumulation of Hydrate-Bearing Sediments in Gas Chimney System since 30 Kyr BP in the QiongDongNan Area, Northern South China Sea (2024)
    MDPI
    Details
    Publication Date: 2024-06-13
    Description: A stratigraphic complex composed of mass transport deposits (MTDs), where the gas occurrence allows for the formation of a gas chimney and pipe structure, is identified based on seismic interpretation in the QiongDongNan area of the northern South China Sea. During the Fifth Gas Hydrate Drilling Expedition of the Guangzhou Marine Geological Survey, this type of complex morphology that has close interaction with local gas hydrate (GH) distribution was eventually confirmed. A flow-reaction model is built to explore the spatial–temporal matching evolution process of massive GH reservoirs since 30 kyr before the present (BP). Five time snapshots, including 30, 20, 10, and 5 kyr BP, as well as the present, have been selected to exhibit key strata-evolving information. The results of in situ tensile estimation imply fracturing emergence occurs mostly at 5 kyr BP. Six other environmental scenarios and three cases of paleo-hydrate existence have been compared. The results almost coincide with field GH distribution below the bottom MTD from drilling reports, and state layer fracturing behaviors always feed and probably propagate in shallow sediments. It can be concluded that this complex system with 10% pre-existing hydrates results in the exact distribution and occurrence in local fine-grained silty clay layers adjacent to upper MTDs.
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  • 7
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    Reassessing the need for carbon dioxide removal: moral implications of alternative climate target pathways (2024)
    Cambridge University Press
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    Publication Date: 2024-06-27
    Description: Non-technical summary Scenarios compatible with the Paris agreement's temperature goal of 1.5 °C involve carbon dioxide removal measures - measures that actively remove CO2 from the atmosphere - on a massive scale. Such large-scale implementations raise significant ethical problems. Van Vuuren et al. (2018), as well as the current IPCC scenarios, show that reduction in energy and or food demand could reduce the need for such activities. There is some reluctance to discuss such societal changes. However, we argue that policy measures enabling societal changes are not necessarily ethically problematic. Therefore, they should be discussed alongside techno-optimistic approaches in any kind of discussions about how to respond to climate change. Technical summary The 1.5 °C goal has given impetus to carbon dioxide removal (CDR) measures, such as bioenergy combined with carbon capture and storage, or afforestation. However, land-based CDR options compete with food production and biodiversity protection. Van Vuuren et al. (2018) looked at alternative pathways including lifestyle changes, low-population projections, or non-CO2 greenhouse gas mitigation, to reach the 1.5 °C temperature objective. Underlined by the recently published IPCC AR6 WGIII report, they show that demand-side management measures are likely to reduce the need for CDR. Yet, policy measures entailed in these scenarios could be associated with ethical problems themselves. In this paper, we therefore investigate ethical implications of four alternative pathways as proposed by Van Vuuren et al. (2018). We find that emission reduction options such as lifestyle changes and reducing population, which are typically perceived as ethically problematic, might be less so on further inspection. In contrast, options associated with less societal transformation and more techno-optimistic approaches turn out to be in need of further scrutiny. The vast majority of emission reduction options considered are not intrinsically ethically problematic; rather everything rests on the precise implementation. Explicitly addressing ethical considerations when developing, advancing, and using integrated assessment scenarios could reignite debates about previously overlooked topics and thereby support necessary societal discourse. Social media summary Policy measures enabling societal changes are not necessarily as ethically problematic as commonly presumed and reduce the need for large-scale CDR
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  • 8
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    What Is Missing in Offshore Explosive Ordnance Disposal Risk Assessment? (2024)
    MDPI
    Details
    Publication Date: 2024-07-03
    Description: Offshore explosive ordnance disposal (EOD) in the marine environment is a high-risk activity. Structured risk assessment (RA) can be a helpful tool to provide EOD experts with decision-making support. This paper hypothesizes that existing RA approaches that address unexploded ordnance (UXO) in the sea do not meet the requirements of EOD RA. To test this hypothesis, the paper proposes a novel categorization tool. It uses five review criteria: study type (qualitative vs. quantitative), level of decision-making (strategic vs. applied), risk component (probability vs. consequence), spatial scale (global vs. local), and temporal scale (long-term vs. short-term). The categorization tool is used to identify the requirements of EOD RA and to test whether nine existing RA methods fulfill these requirements. The study finds that none of the investigated RAs meets the requirements and, hence, concludes that a new method should be developed. However, some aspects of the existing studies should be considered when designing a new method. This includes using risk factors (type and mass of explosive material, type and state of the fuze, and water depth) that are relevant for EOD RA. It also involves setting up a directed graph to assess the complex interdependencies between these risk factors.
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  • 9
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    Range of 21st century ice mass changes in the Filchner-Ronne region of Antarctica (2023)
    Cambridge University Press
    Details
    Publication Date: 2023-06-15
    Description: Increases in ocean temperatures in the Filchner Ronne region of Antarctica are likely to result in increased ice mass loss and sea level rise. We constrain projections of the 21st century sea level contribution of this region using process-based ice-sheet modeling, with model parameters controlling ice dynamics calibrated using observed surface speeds and Markov-chain Monte Carlo sampling. We use climate forcing from Representative Concentration Pathway (RCP) scenarios as well as a set of hypothetical scenarios of deep ocean warming to evaluate the sensitivity of this region to ocean temperatures. Projected changes in regional ice mass correspond to a decrease in global mean sea level of 24±7 mm over 2015–2100 under RCP 2.6 and 28±9 mm under RCP 8.5. Increased regional inland surface accumulation related to higher warming levels in RCP 8.5 leads to more ice above flotation, offsetting increased ice shelf basal melt. The tests involving step changes in ocean temperatures with constant surface forcing show that one degree of ocean warming from present results in an additional +11 mm contribution to sea level by 2100 and 1% of the ice-covered area in the domain becomes ungrounded (23 200 km2). The rate of mass loss with temperature increases at higher temperatures.
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  • 10
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    A response to cummunity questions on the Marine20 Radiocarbon age calibration curve: marine reservoir ages and the calibration of 14C samples from the oceans (2023)
    Cambridge University Press
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    Publication Date: 2024-01-08
    Description: Radiocarbon (14C) concentrations in the oceans are different from those in the atmosphere. Understanding these ocean-atmospheric 14C differences is important both to estimate the calendar ages of samples which obtained their 14C in the marine environment, and to investigate the carbon cycle. The Marine20 radiocarbon age calibration curve is created to address these dual aims by providing a global-scale surface ocean record of radiocarbon from 55,000–0 cal yr BP that accounts for the smoothed response of the ocean to variations in atmospheric 14C production rates and factors out the effect of known changes in global-scale palaeoclimatic variables. The curve also serves as a baseline to study regional oceanic 14C variation. Marine20 offers substantial improvements over the previous Marine13 curve. In response to community questions, we provide a short intuitive guide, intended for the lay-reader, on the construction and use of the Marine20 calibration curve. We describe the choices behind the making of Marine20, as well as the similarities and differences compared with the earlier Marine calibration curves. We also describe how to use the Marine20 curve for calibration and how to estimate ΔR—the localized variation in the oceanic 14C levels due to regional factors which are not incorporated in the global-scale Marine20 curve. To aid understanding, illustrative worked examples are provided.
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  • 11
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    Marine radiocarbon calibration in polar regions: a simple approximate approach using Marine20 (2023)
    Cambridge University Press
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    Publication Date: 2024-01-08
    Description: The Marine20 radiocarbon (14C) age calibration curve, and all earlier marine 14C calibration curves from the IntCal group, must be used extremely cautiously for the calibration of marine 14C samples from polar regions (outside ∼ 40ºS–40ºN) during glacial periods. Calibrating polar 14C marine samples from glacial periods against any Marine calibration curve (Marine20 or any earlier product) using an estimate of , the regional 14C depletion adjustment, that has been obtained from samples in the recent (non-glacial) past is likely to lead to bias and overconfidence in the calibrated age. We propose an approach to calibration that aims to address this by accounting for the possibility of additional, localized, glacial 14C depletion in polar oceans. We suggest, for a specific polar location, bounds on the value of during a glacial period. The lower bound may be based on 14C samples from the recent non-glacial (Holocene) past and corresponds to a low-depletion glacial scenario. The upper bound, , representing a high-depletion scenario is found by increasing according to the latitude of the 14C sample to be calibrated. The suggested increases to obtain are based upon simulations of the Hamburg Large Scale Geostrophic Ocean General Circulation Model (LSG OGCM). Calibrating against the Marine20 curve using the upper and lower bounds provide estimates of calibrated ages for glacial 14C samples in high- and low-depletion scenarios which should bracket the true calendar age of the sample. In some circumstances, users may be able to determine which depletion scenario is more appropriate using independent paleoclimatic or proxy evidence.
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  • 12
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    The impact of spatially varying ice sheet basal conditions on sliding at glacial time scales (2023)
    Cambridge University Press
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    Publication Date: 2024-01-24
    Description: Spatially variable basal conditions are thought to govern how ice sheets behave at glacial time scales (〉1000 years) and responsible for changes in dynamics between the core and peripheral regions of the Laurentide and Fennoscandian ice sheets. Basal motion is accomplished via the deformation of unconsolidated sediments, or via sliding of the ice over an undeformable bed. We present an ice sheet sliding module for the Parallel Ice Sheet Model (PISM) that takes into account changes in sediment cover and incorporates surface meltwater. This model routes meltwater, produced at the surface and base of the ice sheet, toward the margin of the ice sheet. Basal sliding is accomplished through the deformation of water saturated sediments, or sliding at the ice-bed interface. In areas with continuous, water saturated sediments, sliding is almost always accomplished through sediment deformation. In areas with incomplete cover, sliding has a stronger dependence on the supply of water. We find that the addition of surface meltwater to the base is a more important factor for ice sheet evolution than the style of sliding. In a glacial cycle simulation, our model causes a more rapid buildup of the Laurentide Ice Sheet.
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  • 13
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    Enhanced Molecular Networking Shows Microbacterium sp. V1 as a Factory of Antioxidant Proline-Rich Peptides (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Two linear proline-rich peptides (1–2), bearing an N-terminal pyroglutamate, were isolated from the marine bacterium Microbacterium sp. V1, associated with the marine sponge Petrosia ficiformis, collected in the volcanic CO2 vents in Ischia Island (South Italy). Peptide production was triggered at low temperature following the one strain many compounds (OSMAC) method. Both peptides were detected together with other peptides (3–8) via an integrated, untargeted MS/MS-based molecular networking and cheminformatic approach. The planar structure of the peptides was determined by extensive 1D and 2D NMR and HR-MS analysis, and the stereochemistry of the aminoacyl residues was inferred by Marfey’s analysis. Peptides 1–8 are likely to arise from Microbacterium V1 tailor-made proteolysis of tryptone. Peptides 1 and 2 were shown to display antioxidant properties in the ferric-reducing antioxidant power (FRAP) assay.
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  • 14
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    Ectothiorhodospira lacustris sp. nov., a New Purple Sulfur Bacterium from Low-Mineralized Soda Lakes That Contains a Unique Pathway for Nitric Oxide Reduction (2023)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Several strains of a Gram-negative, anaerobic photoautotrophic, motile, rod-shaped bacterium, designated as B14B, A-7R, and A-7Y were isolated from biofilms of low-mineralized soda lakes in central Mongolia and Russia (southeast Siberia). They had lamellar stacks as photosynthetic structures and bacteriochlorophyll a as the major photosynthetic pigment. The strains were found to grow at 25–35 °C, pH 7.5–10.2 (optimum, pH 9.0), and with 0–8% (w/v) NaCl (optimum, 0%). In the presence of sulfide and bicarbonate, acetate, butyrate, yeast extract, lactate, malate, pyruvate, succinate, and fumarate promoted growth. The DNA G + C content was 62.9–63.0 mol%. While the 16S rRNA gene sequences confirmed that the new strains belonged to the genus Ectothiorhodospira of the Ectothiorhodospiraceae, comparison of the genome nucleotide sequences of strains B14B, A-7R, and A-7Y revealed that the new isolates were remote from all described Ectothiorhodospira species both in dDDH (19.7–38.8%) and in ANI (75.0–89.4%). The new strains are also genetically differentiated by the presence of a nitric oxide reduction pathway that is lacking from all other Ectiothiorhodospiraceae. We propose to assign the isolates to the new species, Ectothiorhodospira lacustris sp. nov., with the type strain B14BT (=DSM 116064T = KCTC 25542T = UQM 41491T).
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  • 15
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    Artificial Intelligence Forecasting of Marine Heatwaves in the South China Sea Using a Combined U-Net and ConvLSTM System (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Marine heatwaves (MHWs) are extreme events characterized by abnormally high sea surface temperatures, and they have significant impacts on marine ecosystems and human society. The rapid and accurate forecasting of MHWs is crucial for preventing and responding to the impacts they can lead to. However, the research on relevant forecasting methods is limited, and a dedicated forecasting system specifically tailored for the South China Sea (SCS) region has yet to be reported. This study proposes a novel forecasting system utilizing U-Net and ConvLSTM models to predict MHWs in the SCS. Specifically, the U-Net model is used to forecast the intensity of MHWs, while the ConvLSTM model is employed to predict the probability of their occurrence. The indication of an MHW relies on both the intensity forecasted by the U-Net model exceeding threshold T and the occurrence probability predicted by the ConvLSTM model surpassing threshold P. Incorporating sensitivity analysis, optimal thresholds for T are determined as 0.9 °C, 0.8 °C, 1.0 °C, and 1.0 °C for 1-, 3-, 5-, and 7-day forecast lead times, respectively. Similarly, optimal thresholds for P are identified as 0.29, 0.30, 0.20, and 0.28. Employing these thresholds yields the highest forecast accuracy rates of 0.92, 0.89, 0.88, and 0.87 for the corresponding forecast lead times. This innovative approach gives better predictions of MHWs in the SCS, providing invaluable reference information for marine management authorities to make well-informed decisions and issue timely MHW warnings.
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  • 16
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    Analysis of Mesoscale Eddy Merging in the Subtropical Northwest Pacific Using Satellite Remote Sensing Data (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Mesoscale eddies are ubiquitous in the ocean, yet our understanding of their evolutions, particularly eddy merging processes, remains enigmatic. In this study, the merging processes of two cyclonic–cyclonic and two anticyclonic–anticyclonic eddies are analyzed in the Subtropical Northwest Pacific using satellite remote sensing altimetry data. The results reveal that, as eddies approach each other, their contours become connected, leading to the formation of multi-core eddies. Simultaneously, the merging process prompts substantial exchanges of energy and vorticity, resulting in the dissipation of one eddy and the emergence of a more extensive merged eddy. Throughout the merging process, the eddy contours elongate upwards along the centerline (the line connecting eddy centers) and there are distinct changes in both the horizontal and vertical morphology of the eddies. Notably, after the merging, the eddies distinctly exhibit intensified signals of sea surface temperature and vertical temperature anomaly, an outcome of their transformative fusion. The findings of this study significantly enhance our understanding of mesoscale eddy dynamics, particularly in the intricate eddy merging process. However, it is important to note that, due to limitations in vertical observational data, this study does not provide a quantitative portrayal of the vertical mechanisms of eddy merging, which also underscores a pivotal avenue for future research in the field.
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  • 17
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    The Use of Bi-Potentiostat as a Simple and Accurate Electrochemical Approach for the Determination of Orthophosphate in Seawater (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Autonomous on-site monitoring of orthophosphate (PO43−), an important nutrient for primary production in natural waters, is urgently needed. Here, we report on the development and validation of an on-site autonomous electrochemical analyzer for PO43− in seawater. The approach is based on the use of flow injection analysis in conjunction with a dual electrochemical cell (i.e., a bi-potentiostat detector (FIA-DECD) that uses two working electrodes sharing the same reference and counter electrode. The two working electrodes are used (molybdate/carbon paste electrode (CPE) and CPE) to correct for matrix effects. Optimization of squarewave voltammetry parameters (including step potential, amplitude, and frequency) was undertaken to enhance analytical sensitivity. Possible interferences from non-ionic surfactants and humic acid were investigated. The limit of quantification in artificial seawater (30 g/L NaCl, pH 0.8) was 0.014 µM for a linear concentration range of 0.02–3 µM. The system used a Python script for operation and data processing. The analyzer was tested for ship-board PO43- determination during a four-day research cruise in the North Sea. The analyzer successfully measured 34 samples and achieved a good correlation (Pearson’ R = 0.91) with discretely collected water samples analyzed using a laboratory-based colorimetric reference analyzer.
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    Elevated Temperature-Induced Epimicrobiome Shifts in an Invasive Seaweed Gracilaria vermiculophylla (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Epibacterial communities on seaweeds are affected by several abiotic factors such as temperature and acidification. Due to global warming, surface seawater temperatures are expected to increase by 0.5–5 °C in the next century. However, how epibacterial communities associated with seaweeds will respond to global warming remains unknown. In this study, we investigated the response of epibacterial communities associated with the invasive Gracilaria vermiculophylla exposed to 3 °C above ambient temperature for 4 months using a benthocosm system in Kiel, Germany, and 16S rRNA gene amplicon sequencing. The results showed that elevated temperature affected the beta-diversity of the epibacterial communities. Some potential seaweed pathogens such as Pseudoalteromonas, Vibrio, Thalassotalea, and Acinetobacter were identified as indicator genera at the elevated temperature level. Thirteen core raw amplicon sequence variants in the elevated temperature group were the same as the populations distributed over a wide geographical range, indicating that these core ASVs may play an important role in the invasive G. vermicullophylla. Overall, this study not only contributes to a better understanding of how epibacterial communities associated with G. vermiculophylla may adapt to ocean warming, but also lays the foundation for further exploration of the interactions between G. vermiculophylla and its epimicrobiota.
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    Advanced Methods for Natural Products Discovery: Bioactivity Screening, Dereplication, Metabolomics Profiling, Genomic Sequencing, Databases and Informatic Tools, and Structure Elucidation (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Natural Products (NP) are essential for the discovery of novel drugs and products for numerous biotechnological applications. The NP discovery process is expensive and time-consuming, having as major hurdles dereplication (early identification of known compounds) and structure elucidation, particularly the determination of the absolute configuration of metabolites with stereogenic centers. This review comprehensively focuses on recent technological and instrumental advances, highlighting the development of methods that alleviate these obstacles, paving the way for accelerating NP discovery towards biotechnological applications. Herein, we emphasize the most innovative high-throughput tools and methods for advancing bioactivity screening, NP chemical analysis, dereplication, metabolite profiling, metabolomics, genome sequencing and/or genomics approaches, databases, bioinformatics, chemoinformatics, and three-dimensional NP structure elucidation.
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  • 20
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    Metabolic Regulation of Copper Toxicity during Marine Mussel Embryogenesis (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The development of new tools for assessing the health of cultured shellfish larvae is crucial for aquaculture industries to develop and refine hatchery methodologies. We established a large-volume ecotoxicology/health stressor trial, exposing mussel (Perna canaliculus) embryos to copper in the presence of ethylenediaminetetraacetic acid (EDTA). GC/MS-based metabolomics was applied to identify potential biomarkers for monitoring embryonic/larval health and to characterise mechanisms of metal toxicity. Cellular viability, developmental abnormalities, larval behaviour, mortality, and a targeted analysis of proteins involved in the regulation of reactive oxygen species were simultaneously evaluated to provide a complementary framework for interpretative purposes and authenticate the metabolomics data. Trace metal analysis and speciation modelling verified EDTA as an effective copper chelator. Toxicity thresholds for P. canaliculus were low, with 10% developmental abnormalities in D-stage larvae being recorded upon exposure to 1.10 μg·L−1 bioavailable copper for 66 h. Sublethal levels of bioavailable copper (0.04 and 1.10 μg·L−1) caused coordinated fluctuations in metabolite profiles, which were dependent on development stage, treatment level, and exposure duration. Larvae appeared to successfully employ various mechanisms involving the biosynthesis of antioxidants and a restructuring of energy-related metabolism to alleviate the toxic effects of copper on cells and developing tissues. These results suggest that regulation of trace metal-induced toxicity is tightly linked with metabolism during the early ontogenic development of marine mussels. Lethal-level bioavailable copper (50.3 μg·L−1) caused severe metabolic dysregulation after 3 h of exposure, which worsened with time, substantially delayed embryonic development, induced critical oxidative damage, initiated the apoptotic pathway, and resulted in cell/organism death shortly after 18 h of exposure. Metabolite profiling is a useful approach to (1) assess the health status of marine invertebrate embryos and larvae, (2) detect early warning biomarkers for trace metal contamination, and (3) identify novel regulatory mechanisms of copper-induced toxicity.
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  • 21
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    Wanted Dead or Alive: Skeletal Structure Alteration of Cold-Water Coral Desmophyllum pertusum (Lophelia pertusa) from Anthropogenic Stressors (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Ocean acidification (OA) has provoked changes in the carbonate saturation state that may alter the formation and structural biomineralisation of calcium carbonate exoskeletons for marine organisms. Biomineral production in organisms such as cold-water corals (CWC) rely on available carbonate in the water column and the ability of the organism to sequester ions from seawater or nutrients for the formation and growth of a skeletal structure. As an important habitat structuring species, it is essential to examine the impact that anthropogenic stressors (i.e., OA and rising seawater temperatures) have on living corals and the structural properties of dead coral skeletons; these are important contributors to the entire reef structure and the stability of CWC mounds. In this study, dead coral skeletons in seawater were exposed to various levels of pCO2 and different temperatures over a 12-month period. Nanoindentation was subsequently conducted to assess the structural properties of coral samples’ elasticity (E) and hardness (H), whereas the amount of dissolution was assessed through scanning electron microscopy. Overall, CWC samples exposed to elevated pCO2 and temperature show changes in properties which leave them more susceptible to breakage and may in turn negatively impact the formation and stability of CWC mound development.
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  • 22
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    Total Mass Flux in the Northern Humboldt Current System: Rates and Contribution Sources from Central Peru (12° S) (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The total mass flux (TMF) of particulate organic matter (POM) is key for understanding the energetic transfer within the “biological pump” (i.e., involving the carbon cycle), reflecting a critical connection between the surface and the bottom. A fixed multi-sediment trap was installed at 30 m depth in Callao Bay, central Peru from March to December 2020. After recovery, samples were dried and weighed to calculate the TMF and pellet flux. The average TMF was 601.9 mg·m−2·day−1, with 70.2 and 860 mg·m−2·day−1 as the lowest and highest values during “normal conditions”. Zooplankton fecal pellets (ZFP) were found in ovoid (e.g., larvae) and cylindrical (e.g., adult copepods) shapes and their flux contribution to TMF was low, ranging from 0.17 to 85.59 mg·m−2·day−1. In contrast with ZFP, fish fecal pellets (FFP) were found in fragments with a cylindrical shape, and their contribution to the TMF was higher than ZFP, ranging from 1 to 92.56 mg·m−2·day−1. Mean sinking velocities were 4.63 ± 3.47 m·day−1 (ZFP) and 432.27 ± 294.26 m·day−1 (FFP). There is a considerable difference between the ZFP and FFP contributions to TMFs. We discuss the implications of these results regarding a still poorly understood process controlling the POM flux off the Peruvian coast.
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  • 23
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    Identifying Probable Submarine Hydrothermal Spots in North Santorini Caldera Using the Generalized Moments Method (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The presence of active hydrothermal vent fields near residential areas and their possible link to volcanic activity poses a potential hazard to the environment, society, and the economy. By capitalizing on Autonomous Underwater Vehicle sampling methodologies and applying the Generalized Moments Method model for geological and physical processes in these environments, we shed light on the underlying dynamics shaping the physicochemical characteristics of the vents. In this study, we focus on the Northern Caldera of Santorini and, more specifically, on the recorded CTD data (Conductivity, Temperature, Depth). The data sets were collected in 2017 in Santorini using an Autonomous Underwater Vehicle during the GEOMAR POS510 mission. Our research shows that the active vent field within the caldera probably follows a multifractal behavior and exhibits a weak memory effect. Depth Profiles and Time Series show similar behavior among conductivity and temperature. The variance and moments of both parameters underline the existence of two different mechanisms governing the behavior of the vent field. Finally, the structure function shows that changes in the time series are described by a Cauchy–Lorentz distribution.
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  • 24
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    Indications from C:N:P Ratios in Surface Sediments along Land-to-Sea Gradients to Support Coastal Nutrient Management (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Shallow, semi-enclosed coastal systems are particularly prone to eutrophication. Depending on local site conditions and historical nutrient legacies, sea-based measures might be necessary in addition to land-based nutrient removal. In this study, C:N:P ratios were combined with open-source bathymetric information and linked with the prevailing geomorphological and sedimentological regimes to gain insights into nutrient hotspots and understand their sources and fate in coastal waters. Land-based sediment samples were taken behind outlets at three sites in Eckernförde Bay (Baltic Sea), and complemented with ship-based sampling at locations approximately 8 m and 12 m water depth. The total carbon, nitrogen and phosphorus concentrations in surface sediments increased at deeper sites. This suggests that an increased downslope particle transport and deposition regime, based on local geomorphology, might influence nutrient hotspots to a larger extent than proximity to sources (e.g., outlets). Overall, the recorded C:N ratios (mean = 28.12) were closer to the ratio of terrestrial plants than those of marine phytoplankton, indicating allochthonous sources of organic matter.
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  • 25
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    Chemical and Biological Evaluation of Amazonian Medicinal Plant Vouacapoua americana Aubl (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Vouacapoua americana (Fabaceae) is an economically important tree in the Amazon region and used for its highly resistant heartwood as well as for medicinal purposes. Despite its frequent use, phytochemical investigations have been limited and rather focused on ecological properties than on its pharmacological potential. In this study, we investigated the phytochemistry and bioactivity of V. americana stem bark extract and its constituents to identify eventual lead structures for further drug development. Applying hydrodistillation and subsequent GC-MS analysis, we investigated the composition of the essential oil and identified the 15 most abundant components. Moreover, the diterpenoids deacetylchagresnone (1), cassa-13(14),15-dien-oic acid (2), isoneocaesalpin H (3), (+)-vouacapenic acid (4), and (+)-methyl vouacapenate (5) were isolated from the stem bark, with compounds 2 and 4 showing pronounced effects on Methicillin-resistant Staphylococcus aureus and Enterococcus faecium, respectively. During the structure elucidation of deacetylchagresnone (1), which was isolated from a natural source for the first time, we detected inconsistencies regarding the configuration of the cyclopropane ring. Thus, the structure was revised for both deacetylchagresnone (1) and the previously isolated chagresnone. Following our works on Copaifera reticulata and Vatairea guianensis, the results of this study further contribute to the knowledge of Amazonian medicinal plants.
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    A Deep-Learning Based Pipeline for Estimating the Abundance and Size of Aquatic Organisms in an Unconstrained Underwater Environment from Continuously Captured Stereo Video (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The utilization of stationary underwater cameras is a modern and well-adapted approach to provide a continuous and cost-effective long-term solution to monitor underwater habitats of particular interest. A common goal of such monitoring systems is to gain better insight into the dynamics and condition of populations of various marine organisms, such as migratory or commercially relevant fish taxa. This paper describes a complete processing pipeline to automatically determine the abundance, type and estimate the size of biological taxa from stereoscopic video data captured by the stereo camera of a stationary Underwater Fish Observatory (UFO). A calibration of the recording system was carried out in situ and, afterward, validated using the synchronously recorded sonar data. The video data were recorded continuously for nearly one year in the Kiel Fjord, an inlet of the Baltic Sea in northern Germany. It shows underwater organisms in their natural behavior, as passive low-light cameras were used instead of active lighting to dampen attraction effects and allow for the least invasive recording possible. The recorded raw data are pre-filtered by an adaptive background estimation to extract sequences with activity, which are then processed by a deep detection network, i.e., Yolov5. This provides the location and type of organisms detected in each video frame of both cameras, which are used to calculate stereo correspondences following a basic matching scheme. In a subsequent step, the size and distance of the depicted organisms are approximated using the corner coordinates of the matched bounding boxes. The Yolov5 model employed in this study was trained on a novel dataset comprising 73,144 images and 92,899 bounding box annotations for 10 categories of marine animals. The model achieved a mean detection accuracy of 92.4%, a mean average precision (mAP) of 94.8% and an F1 score of 93%.
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    Links between Ikaite Morphology, Recrystallised Ikaite Petrography and Glendonite Pseudomorphs Determined from Polar and Deep-Sea Ikaite (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Petrography of recrystallised ikaite from Ocean Drilling Program material has been presented previously from Nankai Trough and Congo (ex-Zaire) deep-sea fan. This paper expands on the Nankai Trough ikaite observations, drawing on evidence from Laptev Sea, South Georgia, Okhotsk Sea, and coastal lagoon Point Barrow. However, even though many ikaite and glendonite sites occur at high latitudes, it cannot be that ikaite forms exclusively in polar environments, as demonstrated by the occurrences in the low latitude low temperature deep sea sediments offshore Gulf of Guinea (Angola Congo) and mid-latitude deep-sea trenches offshore Japan. Recrystallised ikaite occurs as mm large, zoned calcite crystals in all samples, along with secondary phases of calcite. Our data set is unique in that the origin, storage, and recrystallisation process of natural formed ikaite is recorded in detail and confirms that glendonite petrographic characteristics are a consequence of the structure and chemistry of recrystallising ikaite and not the physical or geochemical environment. The transformation of man-made ikaite to calcite as recorded in laboratory studies, is a process very similar to the one we have observed for natural ikaite. Most significant is that there is variation in the order of the calcite types within a single sample, leading to the conclusion that the variation is a consequence of impurities and geochemical variability in the ikaite, not the external environment. Morphological observations reveal similarities in ikaite and glendonite, this and the similarity in internal textures in glendonite and recrystallised ikaite confirms that glendonite may be used as an indicator of past presence of ikaite.
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    Reproductive Biology of the Golden Cuttlefish Sepia esculenta (Cephalopoda, Sepiida) (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The golden cuttlefish Sepia esculenta is the one of most abundant cuttlefish species around south-east Asia and has a high commercial value. Despite its wide distribution and high commercial value, its reproductive biology is still poorly understood. This study was based on 25 males and 6 females. The potential fecundity (PF) of females was 1701–3719 oocytes, which was an increase, as compared to the previously known values. The oocyte resorption reached up to 13.2% of fecundity. The ovulation pattern was group-synchronous, with a predominance of previtellogenic oocytes. The pre-meiotic and primary growth oocyte phases were absent in mature females. The number of spermatophores carried by an individual male was 146–1698 (length 9–20 mm). The spermatophores were characterised by a cement body consisting of conical oral and cylindrical aboral parts. The ontogenetic changes in the spermatophores and their parts were recorded for the first time in the order of Sepiida. Their sperm content and their adhesive abilities also increased during ontogenesis. The data obtained in the present study significantly increased and corrected the existing knowledge of S. esculenta biology. Moreover, these data help to explain the general patterns of reproductive biology in cuttlefish, as well as in Cephalopoda as a whole.
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    Bioactivity and Metabolome Mining of Deep-Sea Sediment-Derived Microorganisms Reveal New Hybrid PKS-NRPS Macrolactone from Aspergillus versicolor PS108-62 (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: Despite low temperatures, poor nutrient levels and high pressure, microorganisms thrive in deep-sea environments of polar regions. The adaptability to such extreme environments renders deep-sea microorganisms an encouraging source of novel, bioactive secondary metabolites. In this study, we isolated 77 microorganisms collected by a remotely operated vehicle from the seafloor in the Fram Strait, Arctic Ocean (depth of 2454 m). Thirty-two bacteria and six fungal strains that represented the phylogenetic diversity of the isolates were cultured using an One-Strain-Many-Compounds (OSMAC) approach. The crude EtOAc extracts were tested for antimicrobial and anticancer activities. While antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium was common for many isolates, only two bacteria displayed anticancer activity, and two fungi inhibited the pathogenic yeast Candida albicans. Due to bioactivity against C. albicans and rich chemical diversity based on molecular network-based untargeted metabolomics, Aspergillus versicolor PS108-62 was selected for an in-depth chemical investigation. A chemical work-up of the SPE-fractions of its dichloromethane subextract led to the isolation of a new PKS-NRPS hybrid macrolactone, versicolide A (1), a new quinazoline (−)-isoversicomide A (3), as well as three known compounds, burnettramic acid A (2), cyclopenol (4) and cyclopenin (5). Their structures were elucidated by a combination of HRMS, NMR, [α]D, FT-IR spectroscopy and computational approaches. Due to the low amounts obtained, only compounds 2 and 4 could be tested for bioactivity, with 2 inhibiting the growth of C. albicans (IC50 7.2 µg/mL). These findings highlight, on the one hand, the vast potential of the genus Aspergillus to produce novel chemistry, particularly from underexplored ecological niches such as the Arctic deep sea, and on the other, the importance of untargeted metabolomics for selection of marine extracts for downstream chemical investigations.
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    Bioactivity Profiling and Untargeted Metabolomics of Microbiota Associated with Mesopelagic Jellyfish Periphylla Periphylla (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The marine mesopelagic zone extends from water depths of 200 m to 1000 m and is home to a vast number and diversity of species. It is one of the least understood regions of the marine environment with untapped resources of pharmaceutical relevance. The mesopelagic jellyfish Periphylla periphylla is a well-known and widely distributed species in the mesopelagic zone; however, the diversity or the pharmaceutical potential of its cultivable microbiota has not been explored. In this study, we isolated microorganisms associated with the inner and outer umbrella of P. periphylla collected in Irminger Sea by a culture-dependent approach, and profiled their chemical composition and biological activities. Sixteen mostly gram-negative bacterial isolates were selected and subjected to an OSMAC cultivation regime approach using liquid and solid marine broth (MB) and glucose–yeast–malt (GYM) media. Their ethyl acetate (EtOAc) extracts were assessed for cytotoxicity and antimicrobial activity against fish and human pathogens. All, except one extract, displayed diverse levels of antimicrobial activities. Based on low IC50 values, four most bioactive gram-negative strains; Polaribacter sp. SU124, Shewanella sp. SU126, Psychrobacter sp. SU143 and Psychrobacter sp. SU137, were prioritized for an in-depth comparative and untargeted metabolomics analysis using feature-based molecular networking. Various chemical classes such as diketopiperazines, polyhydroxybutyrates (PHBs), bile acids and other lipids were putatively annotated, highlighting the biotechnological potential in P. periphylla-associated microbiota as well as gram-negative bacteria. This is the first study providing an insight into the cultivable bacterial community associated with the mesopelagic jellyfish P. periphylla and, indeed, the first to mine the metabolome and antimicrobial activities of these microorganisms.
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    Combining an Eddy Detection Algorithm with In-Situ Measurements to Study North Brazil Current Rings (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: North Brazil Current (NBC) rings are believed to play a key role in the Atlantic Ocean circulation and climate. Here, we use a new collection of high-resolution in-situ observations acquired during the EUREC4A-OA field experiment together with satellite altimetry to define, with unprecedented detail, the structure and evolution of these eddies. In-situ observations reveal a more complex structure than previously documented. In particular, we highlight a measurable impact of the Amazon outflow in creating a barrier layer over a large portion of the eddies. We show that this unprecedented data set allows us to estimate the accuracy of satellite altimetry gridded fields. The geostrophic velocities derived from satellite altimetry turn out to be considerably lower (up to 50% in amplitude) than the values measured by current meters. However, eddy properties as detected by TOEddies, a newly developed algorithm show to be relatively precise. For example, the eddy center and maximum azimuthal velocity contour fall within 25 ± 5 km and 16 ± 9 km, respectively, from the in-situ observed values. We apply TOEddies to 27 years of satellite altimetry to investigate the generic NBC rings behavior. We found a mean generation rate of 4.5 ± 1.1 rings per year, and a strong seasonal cycle in all eddy properties.
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    Impact of Enzymatically Extracted High Molecular Weight Fucoidan on Lipopolysaccharide-Induced Endothelial Activation and Leukocyte Adhesion (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The endothelial cell lining creates an interface between circulating blood and adjoining tissue and forms one of the most critical barriers and targets for therapeutical intervention. Recent studies suggest that fucoidans, sulfated and fucose-rich polysaccharides from brown seaweed, show multiple promising biological effects, including anti-inflammatory properties. However, their biological activity is determined by chemical characteristics such as molecular weight, sulfation degree, and molecular structure, which vary depending on the source, species, and harvesting and isolation method. In this study, we investigated the impact of high molecular weight (HMW) fucoidan extract on endothelial cell activation and interaction with primary monocytes (MNCs) in lipopolysaccharide (LPS)-induced inflammation. Gentle enzyme-assisted extraction combined with fractionation by ion exchange chromatography resulted in well-defined and pure fucoidan fractions. FE_F3, with a molecular weight ranging from 110 to 800 kDa and a sulfate content of 39%, was chosen for further investigation of its anti-inflammatory potential. We observed that along with higher purity of fucoidan fractions, the inflammatory response in endothelial mono- and co-cultures with MNCs was reduced in a dose-dependent manner when testing two different concentrations. This was demonstrated by a decrease in IL-6 and ICAM-1 on gene and protein levels and a reduced gene expression of TLR-4, GSK3β and NF-kB. Expression of selectins and, consequently, the adhesion of monocytes to the endothelial monolayer was reduced after fucoidan treatment. These data indicate that the anti-inflammatory effect of fucoidans increases with their purity and suggest that fucoidans might be useful in limiting the inflammatory response of endothelial cells in cases of LPS-induced bacterial infection.
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    Phytoplankton Diversity and Co-Dependency in a Stratified Oligotrophic Ecosystem in the South Adriatic Sea (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The oligotrophy of the southern Adriatic Sea is characterized by seasonal stratification which enables nutrient supply to the euphotic layer. A set of interdisciplinary methods was used to elucidate the diversity and co-dependency of bacterio- and phytoplankton of the water column during the stratification period of July 2021. A total of 95 taxa were determined by microscopy: 58 diatoms, 27 dinoflagellates, 6 coccolithophores, and 4 other autotrophs, which included Chlorophyceae, Chrysophyceae, and Cryptophytes. Nanophytoplankton abundances were higher in comparison to microphytoplankton. The prokaryotic plankton community as revealed by HTS was dominated by Proteobacteria (41–73%), Bacteroidota (9.5–27%), and cyanobacteria (1–10%), while the eukaryotic plankton community was composed of parasitic Syndiniales (45–80%), Ochrophyta (2–18%), Ciliophora (2–21%), Chlorophytes (2–4%), Haptophytes (1–4%), Bacillariophyta (1–13%), Pelagophyta (0.5–12%) and Chrysophyta (0.5–3%). Flow cytometry analysis has recorded Prochlorococcus and photosynthetic picoeukaryotes as more abundant in deep chlorophyll maximum (DCM), and Synechococcus and heterotrophic bacteria as most abundant in surface and thermocline layers. Surface, thermocline, and DCM layers were distinct considering community diversity, temperature, and nutrient correlations, while extreme nutrient values at the beginning of the investigating period indicated a possible nutrient flux. Nutrient and temperature were recognized as the main environmental drivers of phytoplankton and bacterioplankton community abundance.
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    Metabolomics and Microbiomics Insights into Differential Surface Fouling of Three Macroalgal Species of Fucus (Fucales, Phaeophyceae) That Co-Exist in the German Baltic Sea (2023)
    MDPI
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    Publication Date: 2024-02-07
    Description: The brown algal genus Fucus provides essential ecosystem services crucial for marine environments. Macroalgae (seaweeds) release dissolved organic matter, hence, are under strong settlement pressure from micro- and macrofoulers. Seaweeds are able to control surface epibionts directly by releasing antimicrobial compounds onto their surfaces, and indirectly by recruiting beneficial microorganisms that produce antimicrobial/antifouling metabolites. In the Kiel Fjord, in the German Baltic Sea, three distinct Fucus species coexist: F. vesiculosus, F. serratus, and F. distichus subsp. evanescens. Despite sharing the same habitat, they show varying fouling levels; F. distichus subsp. evanescens is the least fouled, while F. vesiculosus is the most fouled. The present study explored the surface metabolomes and epiphytic microbiota of these three Fucus spp., aiming to uncover the factors that contribute to the differences in the fouling intensity on their surfaces. Towards this aim, algal surface metabolomes were analyzed using comparative untargeted LC-MS/MS-based metabolomics, to identify the marker metabolites influencing surface fouling. Their epiphytic microbial communities were also comparatively characterized using high-throughput amplicon sequencing, to pinpoint the differences in the surface microbiomes of the algae. Our results show that the surface of the least fouling species, F. distichus subsp. evanescens, is enriched with bioactive compounds, such as betaine lipids MGTA, 4-pyridoxic acid, and ulvaline, which are absent from the other species. Additionally, it exhibits a high abundance of the fungal genera Mucor and Alternaria, along with the bacterial genus Yoonia-Loktanella. These taxa are known for producing antimicrobial/antifouling compounds, suggesting their potential role in the observed fouling resistance on the surface of the F. distichus subsp. evanescens compared to F. serratus and F. vesiculosus. These findings provide valuable clues on the differential surface fouling intensity of Fucus spp., and their importance in marine chemical defense and fouling dynamics.
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    IPPC 2022: Climate Change 2022 : impacts, adaptation and vulnerability : working group II contribution to the sith assessment report of the intergovernmental panel on climate change (2022)
    Cambridge University Press
    Details
    Publication Date: 2023-06-29
    Type: Report , NonPeerReviewed
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  • 36
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    Cross-sectoral Perspectives (2022)
    Cambridge University Press
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    Publication Date: 2023-06-29
    Type: Book chapter , NonPeerReviewed
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  • 37
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    Influence of the Atlantic Multidecadal Oscillation on South American Atmosphere Dynamics and Precipitation (2022)
    MDPI
    Details
    Publication Date: 2024-01-08
    Description: The Atlantic Multidecadal Oscillation (AMO) is coherently linked to climate variations over many parts of the globe. Despite recent achievements, the mechanism by which the AMO influences regional precipitation over South America is not well understood. In this study, we isolate the atmospheric response to the AMO using a water isotope-enabled version of the Community Earth System Model version 1.2 (iCESM1.2) and determine its influence on (sub)tropical South American regional precipitation and atmospheric circulation. The results suggest an interhemispheric seesaw in Hadley circulation strength and that the section of the Atlantic Hadley cell is marked by a stronger upward air component south of the equator during the cold AMO phase. We also find that the precipitation anomalies over (sub)tropical South America during AMO phases are mainly related to changes in the Atlantic Intertropical Convergence Zone (ITCZ) core strength, where in the cold (warm) AMO phase the core region strengthens (weakens) from February to July, while from July to November the core region weakens (strengthens). Our results stress the importance of acknowledging the dynamics of season- and regional-dependent ITCZ responses, as they are sufficient to produce observed AMO-related signals even in the absence of marked changes in the ITCZ position.
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    Geomorphological Data from Detonation Craters in the Fehmarn Belt, German Baltic Sea (2022)
    MDPI
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    Publication Date: 2024-01-08
    Description: Military munitions from World War I and II dumped at the seafloor are a threat to the marine environment and its users. Decades of saltwater exposure make the explosives fragile and difficult to dispose of. If required, the munition is blast-in-place. In August 2019, 42 ground mines were detonated in a controlled manner underwater during a NATO maneuver in the German Natura2000 Special Area of Conservation Fehmarn Belt, the Baltic Sea. In June 2020, four detonation craters were investigated with a multibeam echosounder for the first time. This dataset is represented here as maps of bathymetry, slope angle, and height difference to the surrounding. The circular craters were still clearly visible a year after the detonation. The diameter and depth of the structures were between 7.5–12.6 m and 0.7–2.2 m, respectively. In total, about 321 m2 of the seafloor was destroyed along the track line.
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  • 39
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    AUV navigation correction based on automated Multibeam Tile Matching (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Ocean science and hydroacoustic seafloor mapping rely on accurate navigation underwater. By exploiting terrain information provided by a multibeam echosounder system, it is possible to significantly improve map quality. This article presents an algorithm capable of improving map quality and accuracy by aligning consecutive pings to tiles that are matched pairwise. A globally consistent solution is calculated from these matches. The proposed method has the potential to be used online in addition to other navigation solutions, but is mainly targeted for post processing. The algorithm was tested using different parameter settings on an AUV and a ship-based dataset. The ship-based dataset is publicly available as a benchmark. The original accurate navigation serving as a ground truth, alongside trajectories that include an artificial drift, are available. This allows quantitative comparisons between algorithms and parameter settings.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 40
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    Functional Responses and Additive Multiple Predator Effects of Two Common Wetland Fish (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Understanding trophic interactions is essential for the prediction and measurement of structure and function in aquatic environments. Communities in these ecosystems may be shaped by variables such as predator diversity, prey density and emergent multiple predator effects (MPEs), which are likely to influence trophic dynamics. In this study, we examined the effect of key predatory fish in floodplain wetlands, namely Oreochromis mossambicus and Enteromius paludinosus, towards Chironomidae prey, using a comparative functional response (FR) approach. We used single predator species as well as intra- and interspecific paired species to contrast FRs under multiple predator scenarios. Attack rate and handling time estimates from single predator FRs were used to predict multiple predators’ feeding rates, which were compared to observe multiple predators’ feeding rates to quantify potential MPEs. From single fish trials, each species displayed a significant Type II FR, characterized by high feeding rates at low prey densities. Oreochromis mossambicus had a steeper (initial slope, i.e., higher attack rate) and higher (asymptote of curve, i.e., shorter handling time and higher maximum feeding rate) FR, whereas E. paludinosus exhibited lower-magnitude FRs (i.e., lower attack rate, longer handling time and lower feeding rate). In multiple predator scenarios, feeding rates were well-predicted by those of single predators, both in conspecific and interspecific pairs, and thus we did not find evidence for antagonistic or synergistic MPEs. Predator–prey interactions in wetland systems can have significant consequences on the structure and dynamics of ecological communities. In turn, this could have destabilizing effects on resources in tropical wetlands. These results, although experimental, help us understand how trophic interaction among conspecific or interspecific fish species in Austral tropical wetlands might influence their aquatic prey species. This will help us to understand food web dynamics better.
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  • 41
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    Application of Feature-Based Molecular Networking for Comparative Metabolomics and Targeted Isolation of Stereoisomers from Algicolous Fungi (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Seaweed endophytic (algicolous) fungi are talented producers of bioactive natural products. We have previously isolated two strains of the endophytic fungus, Pyrenochaetopsis sp. FVE-001 and FVE-087, from the thalli of the brown alga Fucus vesiculosus. Initial chemical studies yielded four new decalinoylspirotetramic acid derivatives with antimelanoma activity, namely pyrenosetins A–C (1–3) from Pyrenochaetopsis sp. strain FVE-001, and pyrenosetin D (4) from strain FVE-087. In this study, we applied a comparative metabolomics study employing HRMS/MS based feature-based molecular networking (FB MN) on both Pyrenochaetopsis strains. A higher chemical capacity in production of decalin derivatives was observed in Pyrenochaetopsis sp. FVE-087. Notably, several decalins showed different retention times despite the same MS data and MS/MS fragmentation pattern with the previously isolated pyrenosetins, indicating they may be their stereoisomers. FB MN-based targeted isolation studies coupled with antimelanoma activity testing on the strain FVE-087 afforded two new stereoisomers, pyrenosetins E (5) and F (6). Extensive NMR spectroscopy including DFT computational studies, HR-ESIMS, and Mosher’s ester method were used in the structure elucidation of compounds 5 and 6. The 3′R,5′R stereochemistry determined for compound 6 was identical to that previously reported for pyrenosetin C (3), whose stereochemistry was revised as 3′S,5′R in this study. Pyrenosetin E (5) inhibited the growth of human malignant melanoma cells (A-375) with an IC50 value of 40.9 μM, while 6 was inactive. This study points out significant variations in the chemical repertoire of two closely related fungal strains and the versatility of FB MN in identification and targeted isolation of stereoisomers. It also confirms that the little-known fungal genus Pyrenochaetopsis is a prolific source of complex decalinoylspirotetramic acid derivatives.
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  • 42
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    Nutritional Calcium Supply Dependent Calcium Balance, Bone Calcification and Calcium Isotope Ratios in Rats (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Serum calcium isotopes (δ44/42Ca) have been suggested as a non-invasive and sensitive Ca balance marker. Quantitative δ44/42Ca changes associated with Ca flux across body compartment barriers relative to the dietary Ca and the correlation of δ44/42CaSerum with bone histology are unknown. We analyzed Ca and δ44/42Ca by mass-spectrometry in rats after two weeks of standard-Ca-diet (0.5%) and after four subsequent weeks of standard- and of low-Ca-diet (0.25%). In animals on a low-Ca-diet net Ca gain was 61 ± 3% and femur Ca content 68 ± 41% of standard-Ca-diet, bone mineralized area per section area was 68 ± 15% compared to standard-Ca-diet. δ44/42Ca was similar in the diets, and decreased in feces and urine and increased in serum in animals on low-Ca-diet. δ44/42CaBone was higher in animals on low-Ca-diet, lower in the diaphysis than the metaphysis and epiphysis, and unaffected by gender. Independent of diet, δ44/42CaBone was similar in the femora and ribs. At the time of sacrifice, δ44/42CaSerum inversely correlated with intestinal Ca uptake and histological bone mineralization markers, but not with Ca content and bone mineral density by µCT. In conclusion, δ44/42CaBone was bone site specific, but mechanical stress and gender independent. Low-Ca-diet induced marked changes in feces, serum and urine δ44/42Ca in growing rats. δ44/42CaSerum inversely correlated with markers of bone mineralization.
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  • 43
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    Impacts of Warming and Acidification on Coral Calcification Linked to Photosymbiont Loss and Deregulation of Calcifying Fluid pH (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Corals are globally important calcifiers that exhibit complex responses to anthropogenic warming and acidification. Although coral calcification is supported by high seawater pH, photosynthesis by the algal symbionts of zooxanthellate corals can be promoted by elevated pCO2. To investigate the mechanisms underlying corals’ complex responses to global change, three species of tropical zooxanthellate corals (Stylophora pistillata, Pocillopora damicornis, and Seriatopora hystrix) and one species of asymbiotic cold-water coral (Desmophyllum pertusum, syn. Lophelia pertusa) were cultured under a range of ocean acidification and warming scenarios. Under control temperatures, all tropical species exhibited increased calcification rates in response to increasing pCO2. However, the tropical species’ response to increasing pCO2 flattened when they lost symbionts (i.e., bleached) under the high-temperature treatments—suggesting that the loss of symbionts neutralized the benefit of increased pCO2 on calcification rate. Notably, the cold-water species that lacks symbionts exhibited a negative calcification response to increasing pCO2, although this negative response was partially ameliorated under elevated temperature. All four species elevated their calcifying fluid pH relative to seawater pH under all pCO2 treatments, and the magnitude of this offset (Δ[H+]) increased with increasing pCO2. Furthermore, calcifying fluid pH decreased along with symbiont abundance under thermal stress for the one species in which calcifying fluid pH was measured under both temperature treatments. This observation suggests a mechanistic link between photosymbiont loss (‘bleaching’) and impairment of zooxanthellate corals’ ability to elevate calcifying fluid pH in support of calcification under heat stress. This study supports the assertion that thermally induced loss of photosymbionts impairs tropical zooxanthellate corals’ ability to cope with CO2-induced ocean acidification.
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    Induction of Isochromanones by Co-Cultivation of the Marine Fungus Cosmospora sp. and the Phytopathogen Magnaporthe oryzae (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Microbial co-cultivation is a promising approach for the activation of biosynthetic gene clusters (BGCs) that remain transcriptionally silent under artificial culture conditions. As part of our project aiming at the discovery of marine-derived fungal agrochemicals, we previously used four phytopathogens as model competitors in the co-cultivation of 21 marine fungal strains. Based on comparative untargeted metabolomics analyses and anti-phytopathogenic activities of the co-cultures, we selected the co-culture of marine Cosmospora sp. with the phytopathogen Magnaporthe oryzae for in-depth chemical studies. UPLC-MS/MS-based molecular networking (MN) of the co-culture extract revealed an enhanced diversity of compounds in several molecular families, including isochromanones, specifically induced in the co-culture. Large scale co-cultivation of Cosmospora sp. and M. oryzae resulted in the isolation of five isochromanones from the whole co-culture extract, namely the known soudanones A, E, D (1-3) and their two new derivatives, soudanones H-I (4-5), the known isochromans, pseudoanguillosporins A and B (6, 7), naphtho-γ-pyrones, cephalochromin and ustilaginoidin G (8, 9), and ergosterol (10). Their structures were established by NMR, HR-ESIMS, FT-IR, electronic circular dichroism (ECD) spectroscopy, polarimetry ([α]D), and Mosher’s ester reaction. Bioactivity assays revealed antimicrobial activity of compounds 2 and 3 against the phytopathogens M. oryzae and Phytophthora infestans, while pseudoanguillosporin A (6) showed the broadest and strongest anti-phytopathogenic activity against Pseudomonas syringae, Xanthomonas campestris, M. oryzae and P. infestans. This is the first study assessing the anti-phytopathogenic activities of soudanones.
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  • 45
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    Improvement of On-Site Sensor for Simultaneous Determination of Phosphate, Silicic acid, Nitrate plus Nitrite in Seawater (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Accurate, on-site determinations of macronutrients (phosphate (PO43−), nitrate (NO3−), and silicic acid (H4SiO4)) in seawater in real time are essential to obtain information on their distribution, flux, and role in marine biogeochemical cycles. The development of robust sensors for long-term on-site analysis of macronutrients in seawater is a great challenge. Here, we present improvements of a commercial automated sensor for nutrients (including PO43−, H4SiO4, and NO2− plus NO3−), suitable for a variety of aquatic environments. The sensor uses the phosphomolybdate blue method for PO43−, the silicomolybdate blue method for H4SiO4 and the Griess reagent method for NO2−, modified with vanadium chloride as reducing agent for the determination of NO3−. Here, we report the optimization of analytical conditions, including reaction time for PO43− analysis, complexation time for H4SiO4 analysis, and analyte to reagent ratio for NO3− analysis. The instrument showed wide linear ranges, from 0.2 to 100 μM PO43−, between 0.2 and 100 μM H4SiO4, from 0.5 to 100 μM NO3−, and between 0.4 and 100 μM NO2−, with detection limits of 0.18 μM, 0.15 μM, 0.45 μM, and 0.35 μM for PO43−, H4SiO4, NO3−, and NO2−, respectively. The analyzer showed good precision with a relative standard deviation of 8.9% for PO43−, 4.8% for H4SiO4, and 7.4% for NO2− plus NO3− during routine analysis of certified reference materials (KANSO, Japan). The analyzer performed well in the field during a 46-day deployment on a pontoon in the Kiel Fjord (located in the southwestern Baltic Sea), with a water supply from a depth of 1 m. The system successfully collected 443, 440, and 409 on-site data points for PO43−, Σ(NO3− + NO2−), and H4SiO4, respectively. Time series data agreed well with data obtained from the analysis of discretely collected samples using standard reference laboratory procedures and showed clear correlations with key hydrographic parameters throughout the deployment period.
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  • 46
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    Phytoplankton Surveys in the Arctic Fram Strait Demonstrate the Tiny Eukaryotic Alga Micromonas and Other Picoprasinophytes Contribute to Deep Sea Export (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Critical questions exist regarding the abundance and, especially, the export of picophytoplankton (≤2 µm diameter) in the Arctic. These organisms can dominate chlorophyll concentrations in Arctic regions, which are subject to rapid change. The picoeukaryotic prasinophyte Micromonas grows in polar environments and appears to constitute a large, but variable, proportion of the phytoplankton in these waters. Here, we analyze 81 samples from the upper 100 m of the water column from the Fram Strait collected over multiple years (2009–2015). We also analyze sediment trap samples to examine picophytoplankton contributions to export, using both 18S rRNA gene qPCR and V1-V2 16S rRNA Illumina amplicon sequencing to assess the Micromonas abundance within the broader diversity of photosynthetic eukaryotes based on the phylogenetic placement of plastid-derived 16S amplicons. The material sequenced from the sediment traps in July and September 2010 showed that 11.2 ± 12.4% of plastid-derived amplicons are from picoplanktonic prasinophyte algae and other green lineage (Viridiplantae) members. In the traps, Micromonas dominated (83.6% ± 21.3%) in terms of the overall relative abundance of Viridiplantae amplicons, specifically the species Micromonas polaris. Temporal variations in Micromonas abundances quantified by qPCR were also observed, with higher abundances in the late-July traps and deeper traps. In the photic zone samples, four prasinophyte classes were detected in the amplicon data, with Micromonas again being the dominant prasinophyte, based on the relative abundance (89.4% ± 8.0%), but with two species (M. polaris and M. commoda-like) present. The quantitative PCR assessments showed that the photic zone samples with higher Micromonas abundances (〉1000 gene copies per mL) had significantly lower standing stocks of phosphate and nitrate, and a shallower average depth (20 m) than those with fewer Micromonas. This study shows that despite their size, prasinophyte picophytoplankton are exported to the deep sea, and that Micromonas is particularly important within this size fraction in Arctic marine ecosystems.
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    A Winter-to-Summer Transition of Bacterial and Archaeal Communities in Arctic Sea Ice (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: The Arctic is warming 2–3 times faster than the global average, leading to a decrease in Arctic sea ice extent, thickness, and associated changes in sea ice structure. These changes impact sea ice habitat properties and the ice-associated ecosystems. Sea-ice algal blooms provide various algal-derived carbon sources for the bacterial and archaeal communities within the sea ice. Here, we detail the transition of these communities from winter through spring to early summer during the Norwegian young sea ICE (N-ICE2015) expedition. The winter community was dominated by the archaeon Candidatus Nitrosopumilus and bacteria belonging to the Gammaproteobacteria (Colwellia, Kangiellaceae, and Nitrinocolaceae), indicating that nitrogen-based metabolisms, particularly ammonia oxidation to nitrite by Cand. Nitrosopumilus was prevalent. At the onset of the vernal sea-ice algae bloom, the community shifted to the dominance of Gammaproteobacteria (Kangiellaceae, Nitrinocolaceae) and Bacteroidia (Polaribacter), while Cand. Nitrosopumilus almost disappeared. The bioinformatically predicted carbohydrate-active enzymes increased during spring and summer, indicating that sea-ice algae-derived carbon sources are a strong driver of bacterial and archaeal community succession in Arctic sea ice during the change of seasons. This implies a succession from a nitrogen metabolism-based winter community to an algal-derived carbon metabolism-based spring/ summer community.
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    A Vision on a UNESCO Global Geopark at the Southeastern Dead Sea in Jordan - Geosites and Conceptual Approach (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: A vision for the establishment of a Geopark in Jordan is given in this work, with a subsequent application to the UNESCO Global Geopark programme. The Dead Sea area and its surroundings have suffered strong changes in the last decades, accompanied by a variety of natural hazards related to enhanced erosional processes. The aspiring Geopark will thematically encompass the influence that these changes and related natural hazards, including flash floods and subsidence, have had on the local population, from geological, over historical up to recent times. The hydrogeology and geomorphology, i.e., the connection between erosion by water, dissolution of minerals, and landscape evolution, will be the main guiding theme that connects the Eastern Rim Highlands with the Dead Sea rift valley through ephemeral wadis, vegetated springs areas, and traditionally communities. The creation of the Geopark is aimed at holistic, sustainable development and management of the area by eco-tourism, and includes education on water resource management, hazard awareness and resilience, as well as international research. We here present the conceptual approach to the initial development of a Geopark network in Jordan. In a narrative discourse, we highlight realised and further implementation steps, with an evaluation of the expected timeline, potential partner institutions, regional involvement and the chances for realisation.
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  • 49
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    Assessing Representation Learning and Clustering Algorithms for Computer-Assisted Image Annotation - Simulating and Benchmarking MorphoCluster (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Image annotation is a time-consuming and costly task. Previously, we published MorphoCluster as a novel image annotation tool to address problems of conventional, classifier-based image annotation approaches: their limited efficiency, training set bias and lack of novelty detection. MorphoCluster uses clustering and similarity search to enable efficient, computer-assisted image annotation. In this work, we provide a deeper analysis of this approach. We simulate the actions of a MorphoCluster user to avoid extensive manual annotation runs. This simulation is used to test supervised, unsupervised and transfer representation learning approaches. Furthermore, shrunken k-means and partially labeled k-means, two new clustering algorithms that are tailored specifically for the MorphoCluster approach, are compared to the previously used HDBSCAN*. We find that labeled training data improve the image representations, that unsupervised learning beats transfer learning and that all three clustering algorithms are viable options, depending on whether completeness, efficiency or runtime is the priority. The simulation results support our earlier finding that MorphoCluster is very efficient and precise. Within the simulation, more than five objects per simulated click are being annotated with 95% precision.
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    Maintenance of Intraspecific Diversity in Response to Species Competition and Nutrient Fluctuations (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: Intraspecific diversity is a substantial part of biodiversity, yet little is known about its maintenance. Understanding mechanisms of intraspecific diversity shifts provides realistic detail about how phytoplankton communities evolve to new environmental conditions, a process especially important in times of climate change. Here, we aimed to identify factors that maintain genotype diversity and link the observed diversity change to measured phytoplankton morpho-functional traits Vmax and cell size of the species and genotypes. In an experimental setup, the two phytoplankton species Emiliania huxleyi and Chaetoceros affinis, each consisting of nine genotypes, were cultivated separately and together under different fluctuation and nutrient regimes. Their genotype composition was assessed after 49 and 91 days, and Shannon’s diversity index was calculated on the genotype level. We found that a higher intraspecific diversity can be maintained in the presence of a competitor, provided it has a substantial proportion to total biovolume. Both fluctuation and nutrient regime showed species-specific effects and especially structured genotype sorting of C. affinis. While we could relate species sorting with the measured traits, genotype diversity shifts could only be partly explained. The observed context dependency of genotype maintenance suggests that the evolutionary potential could be better understood, if studied in more natural settings including fluctuations and competition.
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    A Vision on a UNESCO Global Geopark at the Southeastern Dead Sea in Jordan — How Natural Hazards May Offer Geotourism Opportunities (2022)
    MDPI
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    Publication Date: 2024-02-07
    Description: This paper aims to identify and discuss the chances, solutions, and possible drawbacks related to the establishment of safe geotourism sites in subsidence-affected areas, exemplarily applied to the Ghor Al-Haditha sinkhole site at the southeastern shore of the Dead Sea. Such safe areas shall be established in the territory of the proposed future UNESCO Global Geopark (UGGp) in Jordan. The highlights of the geopark and the basis of its creation are the subsidence features and stream channels found along the SE shoreline of the Dead Sea, which form both a natural hazard and geological heritage of high international significance and have attracted many researchers so far. This recent and ongoing formation is related to the sharp regression of the lake, the specific geomechanical conditions, and the hydrogeologic and climatic background of the surroundings. Nearby communities have suffered in economic terms from these natural phenomena, including flash floods and droughts in this semi-arid to arid region. We here present a concept on how to integrate geoscientific research for hazard monitoring and early warning to maintain safety for inhabitants and visitors on the one hand and reach sustainable economic development through the establishment of geotourism sites on the other hand. This highlight area of the proposed UGGp serves as a starting example for delineating safe zones for walkways and infrastructure. This involves two-way knowledge transfer between spatial planning and hydrogeophysical monitoring, a network of community-supported geophysical surveillance, and regular maintenance and adaptation. The cross-cutting benefits for the territory involve the delineation of safe areas for agriculture and geotourism, the increase of sustainable tourism in the region with a shift towards alternative ways of income, more investment in infrastructure, a growth of international visibility of the region, enhanced environmental education with focus on responsible water usage, and involvement in international research and education projects.
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    Polymetallic Sulfide–Quartz Vein System in the Koudiat Aïcha Massive Sulfide Deposit, Jebilet Massif, Morocco: Microanalytical and Fluid Inclusion Approaches (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The Koudiat Aïcha Zn-Cu-Pb deposit (3–Mt ore @ 3 wt.% Zn, 1 wt.% Pb, 0.6 wt.% Cu) in the Jebilet massif (Morocco) comprises stratabound lenticular orebodies and crosscutting sulfide-bearing quartz ± carbonate veins in the lower Carboniferous Sarhlef volcano sedimentary succession. The veins are characterized by abundant pyrrhotite, sphalerite, subordinate chalcopyrite and galena and rare Ag and Au minerals. The stratabound massive sulfide ores are attributed to a “VMS” type, whereas the origin of the sulfide–quartz ± carbonate veins remains poorly understood. New mineralogical and microanalytical data (SEM, EPMA and LA-ICP-MS) combined with fluid inclusion results point to two-stage vein formation. The early stage involved C–H–O–N Variscan metamorphic fluids which percolated through fractures and shear zones and deposited pyrite at 〉400 °C, followed by the formation of pyrrhotite and sphalerite (300 ± 20 °C) in quartz veins and in banded and breccia ores. The pyrrhotite–sphalerite mineralization was overprinted by aqueous brines (34 to 38 wt% eq. NaCl + CaCl2) that precipitated carbonate and Cu-Pb sulfides (±Ag-Au) at ~180–210 °C through mixing with low-salinity fluids during tectonic reworking of early-formed structures and in late extension fractures. The latter ore fluids were similar to widspread post-Variscan evaporitic brines that circulated in the Central Jebilet. Overlapping or successive pulses of different ore fluids, i.e., metamorphic fluids and basinal brines, led to metal enrichment in the quartz–carbonate veins compared to the massive sulfide ores. These results underscore that even a single deposit may record several distinct mineralizing styles, such that the ultimate metal endowment may be cumulative over multiple stages.
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    Comparative Genome Analysis of the Photosynthetic Betaproteobacteria of the Genus Rhodocyclus: Heterogeneity within Strains Assigned to Rhodocyclus tenuis and Description of Rhodocyclus gracilis sp. nov. as a New Species (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The genome sequences for Rhodocyclus purpureus DSM 168T and four strains assigned to Rhodocyclus tenuis (DSM 110, DSM 111, DSM 112, and IM 230) have been determined. One of the strains studied (IM 230) has an average nucleotide identity (ANI) of 97% to the recently reported genome of the type strain DSM 109 of Rcy. tenuis and is regarded as virtually identical at the species level. The ANI of 80% for three other strains (DSM 110, DSM 111, DSM 112) to the type strain of Rcy. tenuis points to a differentiation of these at the species level. Rcy. purpureus is equidistant from Rcy. tenuis and the new species, based on both ANI (78–80%) and complete proteome comparisons (70% AAI). Strains DSM 110, DSM 111, and DSM 112 are very closely related to each other based on ANI, whole genome, and proteome comparisons but clearly distinct from the Rcy. tenuis type strain DSM 109. In addition to the whole genome differentiation, these three strains also contain unique genetic differences in cytochrome genes and contain genes for an anaerobic cobalamin synthesis pathway that is lacking from both Rcy. tenuis and Rcy. purpureus. Based on genomic and genetic differences, these three strains should be considered to represent a new species, which is distinctly different from both Rcy. purpureus and Rcy. tenuis, for which the new name Rhodocyclus gracilis sp. nov. is proposed.
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  • 54
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    Biotic and abiotic drivers affect parasite richness, prevalence and abundance in Mytilus galloprovincialis along the Northern Adriatic Sea (2022)
    Cambridge University Press
    Details
    Publication Date: 2024-02-07
    Description: Although it is generally known that a combination of abiotic and biotic drivers shapes the distribution and abundance of parasites, our understanding of the interplay of these factors remains to be assessed for most marine host species. The present field survey investigated spatial patterns of richness, prevalence and abundance of parasites in Mytilus galloprovincialis along the coast of the northern Adriatic Sea. Herein, the relationships between biotic (host size, density and local parasite richness of mussel population) and abiotic (eutrophication and salinity) drivers and parasite richness of mussel individuals, prevalence and abundance were analysed. Local parasite richness was the most relevant factor driving parasite species richness in mussel individuals. Prevalence was mainly driven by eutrophication levels in 3 out of 4 parasite species analysed. Similarly, abundance was driven mainly by eutrophication in two parasite species. Mussel size, density and salinity had only minor contributions to the best fitting models. This study highlights that the influence of abiotic and biotic drivers on parasite infections in mussels can be differentially conveyed, depending on the infection measure applied, i.e., parasite richness, prevalence or abundance. Furthermore, it stresses the importance of eutrophication as a major factor influencing parasite prevalence and abundance in mussels in the Adriatic Sea
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  • 55
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    The Diversity, Metabolomics Profiling, and the Pharmacological Potential of Actinomycetes Isolated from the Estremadura Spur Pockmarks (Portugal) (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The Estremadura Spur pockmarks are a unique and unexplored ecosystem located in the North Atlantic, off the coast of Portugal. A total of 85 marine-derived actinomycetes were isolated and cultured from sediments collected from this ecosystem at a depth of 200 to 350 m. Nine genera, Streptomyces, Micromonospora, Saccharopolyspora, Actinomadura, Actinopolymorpha, Nocardiopsis, Saccharomonospora, Stackebrandtia, and Verrucosispora were identified by 16S rRNA gene sequencing analyses, from which the first two were the most predominant. Non-targeted LC-MS/MS, in combination with molecular networking, revealed high metabolite diversity, including several known metabolites, such as surugamide, antimycin, etamycin, physostigmine, desferrioxamine, ikarugamycin, piericidine, and rakicidin derivatives, as well as numerous unidentified metabolites. Taxonomy was the strongest parameter influencing the metabolite production, highlighting the different biosynthetic potentials of phylogenetically related actinomycetes; the majority of the chemical classes can be used as chemotaxonomic markers, as the metabolite distribution was mostly genera-specific. The EtOAc extracts of the actinomycete isolates demonstrated antimicrobial and antioxidant activity. Altogether, this study demonstrates that the Estremadura Spur is a source of actinomycetes with potential applications for biotechnology. It highlights the importance of investigating actinomycetes from unique ecosystems, such as pockmarks, as the metabolite production reflects their adaptation to this habitat.
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  • 56
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    Gut and Gill-Associated Microbiota of the Flatfish European Plaice (Pleuronectes platessa): Diversity, Metabolome and Bioactivity against Human and Aquaculture Pathogens (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Similar to other marine holobionts, fish are colonized by complex microbial communities that promote their health and growth. Fish-associated microbiota is emerging as a promising source of bioactive metabolites. Pleuronectes platessa (European plaice, plaice), a flatfish with commercial importance, is common in the Baltic Sea. Here we used a culture-dependent survey followed by molecular identification to identify microbiota associated with the gills and the gastrointestinal tract (GIT) of P. platessa, then profiled their antimicrobial activity and metabolome. Altogether, 66 strains (59 bacteria and 7 fungi) were isolated, with Proteobacteria being the most abundant phylum. Gill-associated microbiota accounted for higher number of isolates and were dominated by the Proteobacteria (family Moraxellaceae) and Actinobacteria (family Nocardiaceae), whereas Gram-negative bacterial families Vibrionaceae and Shewanellaceae represented the largest group associated with the GIT. The EtOAc extracts of the solid and liquid media cultures of 21 bacteria and 2 fungi representing the diversity of cultivable plaice-associated microbiota was profiled for their antimicrobial activity against three fish pathogens, human bacterial pathogen panel (ESKAPE) and two human fungal pathogens. More than half of all tested microorganisms, particularly those originating from the GIT epithelium, exhibited antagonistic effect against fish pathogens (Lactococcus garvieae, Vibrio ichthyoenteri) and/or human pathogens (Enterococcus faecium, methicillin-resistant Staphylococcus aureus). Proteobacteria represented the most active isolates. Notably, the solid media extracts displayed higher activity against fish pathogens, while liquid culture extracts were more active against human pathogens. Untargeted metabolomics approach using feature-based molecular networking showed the high chemical diversity of the liquid extracts that contained undescribed clusters. This study highlights plaice-associated microbiota as a potential source of antimicrobials for the control of human and the aquaculture-associated infections. This is the first study reporting diversity, bioactivity and chemical profile of culture-dependent microbiota of plaice.
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  • 57
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    Classification Ensembles for Beach Cast and Drifting Vegetation Mapping with Sentinel-2 and PlanetScope (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Along the Baltic coastline of Germany, drifting vegetation and beach cast create overlays at the otherwise sandy or stony beaches. These overlays influence the morphodynamics and structures of the beaches. To better understand the influence of these patchy habitats on coastal environments, regular monitoring is necessary. Most studies, however, have been conducted on spatially larger and temporally more stable occurrences of aquatic vegetation such as floating fields of Sargassum. Nevertheless, drifting vegetation and beach cast pose a particular challenge, as they exhibit high temporal dynamics and sometimes small spatial extent. Regular surveys and mappings are the traditional methods to record their habitats, but they are time-consuming and cost-intensive. Spaceborne remote sensing can provide frequent recordings of the coastal zone at lower cost. Our study therefore aims at the monitoring of drifting vegetation and beach cast on spatial scales between 3 and 10 m. We developed an automated coastline masking algorithm and tested six supervised classification methods and various classification ensembles for their suitability to detect small-scale assemblages of drifting vegetation and beach cast in a study area at the coastline of the Western Baltic Sea using multispectral data of the sensors Sentinel-2 MSI and PlanetScope. The shoreline masking algorithm shows high accuracies in masking the land area while preserving the sand-covered shoreline. We could achieve best classification results using PlanetScope data with an ensemble of a random forest classifier, cart classifier, support vector machine classifier, naïve bayes classifier and stochastic gradient boosting classifier. This ensemble accomplished a combined f1-score of 0.95. The accuracy of the Sentinel-2 classifications was lower but still achieved a combined f1-score of 0.86 for the same ensemble. The results of this study can be considered as a starting point for the development of time series analysis of the vegetation dynamics along Baltic beaches
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  • 58
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    Genomic Comparison, Phylogeny and Taxonomic Reevaluation of the Ectothiorhodospiraceae and Description of Halorhodospiraceae fam. nov. and Halochlorospira gen. nov. (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The Ectothiorhodospiraceae family represents purple sulfur bacteria of the Gammaproteobacteria found primarily in alkaline soda lakes of moderate to extremely high salinity. The main microscopi-cally visible characteristic separating them from the Chromatiaceae is the excretion of the intermediate elemental sulfur formed during oxidation of sulfide prior to complete oxidation to sulfate rather than storing it in the periplasm. We present a comparative study of 38 genomes of all species of phototrophic Ectothiorhodospiraceae. We also include a comparison with those chemotrophic bacteria that have been assigned to the family previously and critically reevaluate this assignment. The data demonstrate the separation of Halorhodospira species in a major phylogenetic branch distant from other Ectothiorhodospiraceae and support their separation into a new family, for which the name Halorho-dospiraceae fam. nov. is proposed. In addition, the green-colored, bacteriochlorophyll-containing species Halorhodospira halochloris and Halorhodospira abdelmalekii were transferred to the new genus Halochlorospira gen. nov. of this family. The data also enable classification of several so far unclassified isolates and support the separation of Ectothiorhodospira shaposhnikovii and Ect. vacuolata as well as Ect. mobilis and Ect. marismortui as distinct species.
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  • 59
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    Experimental and Numerical Modelling of Deep-Sea-Mining-Generated Turbidity Currents (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Renewable energy installations and energy storage solutions require significant quantities of critical raw materials such as nickel, cobalt and rare earth metals. The supply chains of these raw materials face many difficulties, such as the continuous decrease of mineral ore grades on land. In view of these complications, the motivation to search for new resources has grown, with the deep sea being seen as a potential source of these minerals. Polymetallic nodule mining generates turbidity currents, which could negatively impact the deep-sea environment. For that reason, we investigate this type of current experimentally and numerically in order to characterize the generated turbidity current. Various non-cohesive sediment types, i.e., different particle sizes, and different concentrations are tested using a lock-exchange set-up. Three sediment types (glass beads, silica sand and a 50/50 blend of glass beads and silica sand) with seven initial sediment concentrations are examined. Additionally, for the numerical work, a drift–flux modelling approach is used to simulate the performed lock-exchange experiments. The results show that the front velocities of the currents resulting from the three sediment types increases with increasing initial concentrations inside the lock regardless. Moreover, using the same initial concentration, the difference in front velocities between the generated currents of the three sediment types decreases as the initial concentration increases. When using an initial volumetric concentration of 2.5% and 3%, the difference in front velocities between the generated current of the three sediment types vanishes. Finally, by comparing the numerical and experimental results, the drift–flux model is proven to be a reliable numerical model for predicting the current.
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  • 60
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    Behavioural Responses and Mortality of Mozambique Tilapia Oreochromis mossambicus to Three Commonly Used Macadamia Plantation Pesticides (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The use of pesticides in agricultural systems may have deleterious effects on surrounding environments. Aquatic systems are no exception and are increasingly polluted through the leaching of pesticides from agricultural activities. However, the pesticide pollution effects on key aquatic species have not been studied in many regions. In southern Africa, increasing pesticide use associated with macadamia tree Macadamia integrifolia farming presents a growing risk to surrounding aquatic ecosystems. This study assessed behavioural responses of an important and widely-distributed freshwater fish, Mozambique tilapia Oreochromis mossambicus, following exposure to three commonly used macadamia pesticides (i.e., Karate Zeon 10 CS, Mulan 20 SP, Pyrinex 250 CS) at different concentrations (0.7–200 µL, 0.3–1000 mg, and 0.7–8750 µL, respectively) over 24 h. Behavioural responses, i.e., swimming erratically, surfacing, vertical positioning, loss of equilibrium, being motionless and mortality were observed after pesticides exposure. Lethal dose 50 (LD50) values of Karate Zeon 10 CS, Mulan 20 SP and Pyrinex 250 CS were 2.1 µL (per water litre dilution—WLD), 5.2 mg (WLD) and 21.5 µL (WLD), respectively. These concentrations are therefore expressed as a maximal threshold usage in the environment around macadamia farms and a minimum distance of the plantations to water systems should be considered. Further studies should examine effects on other fish species and aquatic invertebrates to inform on pesticide pollution threats and mitigation plans for the region.
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    Calcium Carbonate Hexahydrate (Ikaite): History of Mineral Formation as Recorded by Stable Isotopes (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Calcium carbonate hexahydrate (ikaite) is a rare mineral that forms as metastable species in the organic-carbon-rich sediments of the King George Basin, Bransfield Strait, Antarctica, as a consequence of early diagenetic decomposition of organic matter under cold water (−1.4 °C) and high pressure (200 bar) conditions. Large crystals grow in the sediment immediately below the diagenetic transition between microbial sulfate reduction and methanogenesis at ~320 cm below sea floor (bsf). This process is reflected in the dissolved sulfate, total carbon dioxide, and methane concentrations, as well as in the carbon, hydrogen, and oxygen isotope chemistries of the interstitial fluids and dissolved gases of the host sediment. The ikaite crystal faithfully records in its zonal structure the changing carbon isotope ratio of the total dissolved carbon dioxide pool as it gradually diminishes during methanogenesis (δ13Cikaite = −17.5 to −21.4‰). These changes in the crystal’s host environment follow general Rayleigh carbon isotope fractionation. The oxygen isotopes of the ikaite carbonate (δ18Oikaite = 1.46 to 4.45‰) also show a strong zonal distribution, unrelated to temperature of formation, but perhaps controlled by the degree of recrystallization of ikaite to calcite. The crystal water of the ikaite is depleted 11‰ in 2H/1H (VSMOW) relative to the coexisting interstitial water, which is in excellent agreement with the isotope fractionation of other hydrated minerals. In addition to the in situ temperature and pressure, nucleation of the ikaite crystals in the Bransfield Basin sediments may be induced by the high alkalinity, high phosphate concentrations, and dissolved organic compounds. Intense microbial metabolism generates such compounds; of these, aspartic acid and glutamic acid may play an important role, as they do in biological and extracellular carbonate mineral precipitation. All indications are that low temperatures (such as of polar environments), high calcium carbonate supersaturation caused by interstitial methanogenesis, and a sufficiently large supply of dissolved phosphate and amino acids favor metastable ikaite formation. These conditions, modified by recrystallization, may be preserved in calcite glendonites, thinolites, and other calcitic pseudomorphs derived from ikaite and found throughout the ancient sedimentary record.
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    Life History of the Arctic Squid Gonatus fabricii (Cephalopoda: Oegopsida) Reconstructed by Analysis of Individual Ontogenetic Stable Isotopic Trajectories (2022)
    MDPI
    Details
    Publication Date: 2024-04-18
    Description: Cephalopods are important in Arctic marine ecosystems as predators and prey, but knowledge of their life cycles is poor. Consequently, they are under-represented in the Arctic ecosystems assessment models. One important parameter is the change in ecological role (habitat and diet) associated with individual ontogenies. Here, the life history of Gonatus fabricii, the most abundant Arctic cephalopod, is reconstructed by the analysis of individual ontogenetic trajectories of stable isotopes (δ13C and δ15N) in archival hard body structures. This approach allows the prediction of the exact mantle length (ML) and mass when the species changes its ecological role. Our results show that the life history of G. fabricii is divided into four stages, each having a distinct ecology: (1) epipelagic squid (ML 〈 20 mm), preying mostly on copepods; (2) epi- and occasionally mesopelagic squid (ML 20–50 mm), preying on larger crustaceans, fish, and cephalopods; (3) meso- and bathypelagic squid (ML 〉 50 mm), preying mainly on fish and cephalopods; and (4) non-feeding bathypelagic gelatinous females (ML 〉 200 mm). Existing Arctic ecosystem models do not reflect the different ecological roles of G. fabricii correctly, and the novel data provided here are a necessary baseline for Arctic ecosystem modelling and forecasting.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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    Observing Earth’s magnetic environment with the GRACE-FO mission (2021)
    Stolle, C. ; Michaelis, I. ; Xiong, C. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission carries magnetometers that are dedicated to enhance the satellite’s navigation. After appropriate calibration and characterisation of artificial magnetic disturbances, these observations are valuable assets to characterise the natural variability of Earth’s magnetic field. We describe the data pre-processing, the calibration, and characterisation strategy against a high-precision magnetic field model applied to the GRACE-FO magnetic data. During times of geomagnetic quiet conditions, the mean residual to the magnetic model is around 1 nT with standard deviations below 10 nT. The mean difference to data of ESA’s Swarm mission, which is dedicated to monitor the Earth’s magnetic field, is mainly within ± 10 nT during conjunctions. The performance of GRACE-FO magnetic data is further discussed on selected scientific examples. During a magnetic storm event in August 2018, GRACE-FO reveals the local time dependence of the magnetospheric ring current signature, which is in good agreement with results from a network of ground magnetic observations. Also, derived field-aligned currents (FACs) are applied to monitor auroral FACs that compare well in amplitude and statistical behaviour for local time, hemisphere, and solar wind conditions to approved earlier findings from other missions including Swarm. On a case event, it is demonstrated that the dual-satellite constellation of GRACE-FO is most suitable to derive the persistence of auroral FACs with scale lengths of 180 km or longer. Due to a relatively larger noise level compared to dedicated magnetic missions, GRACE-FO is especially suitable for high-amplitude event studies. However, GRACE-FO is also sensitive to ionospheric signatures even below the noise level within statistical approaches. The combination with data of dedicated magnetic field missions and other missions carrying non-dedicated magnetometers greatly enhances related scientific perspectives.
    Description: European Space Agency (FR)
    Description: HEIBRIDS
    Description: Projekt DEAL
    Description: ftp://isdcftp.gfz-potsdam.de/grace-fo/MAGNETIC_FIELD
    Keywords: ddc:538.7 ; Earth’s magnetic field ; Geomagnetism ; Ionospheric currents ; Magnetospheric ring current ; Satellite-based magnetometers ; Platform magnetometers ; GRACE-FO
    Language: English
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    The Niederschlag fluorite-(barite) deposit, Erzgebirge/Germany—a fluid inclusion and trace element study (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: The Niederschlag fluorite-barite vein deposit in the Western Erzgebirge, Germany, has been actively mined since 2013. We present the results of a first comprehensive study of the mineralogy, petrography, fluid inclusions, and trace element geochemistry of fluorite related to the Niederschlag deposit. Two different stages of fluorite mineralization are recognized. Stage I fluorite is older, fine-grained, associated with quartz, and forms complex breccia and replacement textures. Conversely, the younger Stage II fluorite is accompanied by barite and often occurs as banded and coarse crystalline open-space infill. Fluid inclusion and REY systematics are distinctly different for these two fluorite stages. Fluid inclusions in fluorite I reveal the presence of a low to medium saline (7–20% eq. w (NaCl+CaCl2)) fluid with homogenization temperatures of 140–180 °C, whereas fluorite II inclusions yield distinctly lower (80–120 °C) homogenization temperatures with at least two high salinity fluids involved (18–27% eq. w (NaCl+CaCl2)). In the absence of geochronological data, the genesis of the earlier generation of fluorite-quartz mineralization remains enigmatic but is tentatively related to Permian magmatism in the Erzgebirge. The younger fluorite-barite mineralization, on the other hand, has similarities to many fluorite-barite-Pb-Zn-Cu vein deposits in Europe that are widely accepted to be related to the Mesozoic opening of the northern Atlantic Ocean.
    Description: European Social Fund http://dx.doi.org/10.13039/501100004895
    Keywords: ddc:553.6 ; Fluorite ; Microthermometry ; Fluid inclusions ; Rare earth elements ; Geochemistry ; Metallogenesis ; Industrial minerals
    Language: English
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    The Schlaining quartz-stibnite deposit, Eastern Alps, Austria: constraints from conventional and infrared microthermometry and isotope and crush-leach analyses of fluid inclusions (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-21
    Description: Stibnite was mined until the end of the twentieth century in the Schlaining ore district, Austria, near the easternmost border of the Eastern Alps where windows of Penninic ophiolites and metasediments are exposed below Austroalpine tectonic units. In Early Miocene, structurally controlled small vein and metasomatic stibnite-quartz deposits were formed in Penninic Mesozoic calcareous marbles and calcite schists. Fluid inclusion studies identified two fluids involved in the mineralization: (i) a low-salinity, low-CO2 metamorphic fluid that precipitated quartz at approximately 240 °C and (ii) a stibnite-forming ore fluid that had a meteoric origin. There is no evidence of boiling or that the fluids mixed during mineralization. The ore components Sb and H2S were leached by fluid/rock interaction from buried rock units. Stibnite mineralization occurred by cooling the ore fluid to below 300 °C, at less than 2000 m depth. Quartz precipitated at slightly lower temperatures, approximately contemporaneous with stibnite. Fluid migration and ore deposition are probably related to high heat flow during the exhumation of the Rechnitz Window in response to Neogene extension and/or shallow Early Miocene andesitic magmatism. The study emphasizes that data obtained from the analyses of gangue minerals alone cannot routinely be used to infer the origin and depositional conditions of the associated ore minerals.
    Description: Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ (4217)
    Keywords: ddc:553.4 ; Geology ; Mineral Resources ; Mineralogy
    Language: English
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    Youngest Cretaceous dinosaur tracksite from the Middle East (Maastrichtian, Farrokhi Formation, Central Iran) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-19
    Description: A late early Maastrichtian dinosaur trampling site is reported from the Farrokhi Formation of the Khur area, Central Iran. The largely indeterminate footprints, some of which may represent undertracks, can be classified as natural moulds (i.e. concave epireliefs) bordered by a raised rim of displaced sediment. They reach diameters of up to 0.5 m and were impressed under very shallow to subaerial conditions in an inter- to supratidal environment. Two generations of traces have been imprinted, initially into a soft, fine-grained carbonate sand and afterwards into a superficially hardened substrate that was still plastic underneath; the change in substrate consistency is supported by a conspicuous cracking pattern around the footprints. As a result, hardly any details of the foot morphology of the trackmakers are recorded. Nevertheless, the occurrence improves our knowledge about dinoturbation and its preservation in different kinds of substrates. Furthermore, it is the youngest record (ca. 70 Ma) of dinosaur locomotion traces from Iran and, in all probability, the entire Middle East.
    Description: Senckenberg Naturhistorische Sammlungen Dresden (3507)
    Keywords: ddc:560 ; Late Cretaceous ; Yazd Block ; Tidal flats ; Dinoturbation ; Emersion ; Composite surface
    Language: English
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    Created by the Monte Peron rock avalanche: Lago di Vedana (Dolomites, Italy) and its sediment record of landscape evolution after a mass wasting event (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-19
    Description: The timing of the Monte Peron Landslide is revised to 2890 cal. BP based on a radiocarbon-dated sediment stratigraphy of Lago di Vedana. This age fosters the importance of hydroclimatic triggers in the light of accelerating global warming with a predicted increase of precipitation enhancing the regional predisposition to large landslides. Moreover, a layer enriched in allochthonous organic and minerogenic detritus dating to the same wet period is interpreted as response to a younger and yet unidentified mass wasting event in the catchment of Lago di Vedana. Rock debris of the Monte Peron Landslide impounded the Cordevole River valley and created a landslide-dammed lake. Around AD 1150, eutrophication of this lacustrine ecosystem started with intensified human occupation – a process that ended 150 years later, when the river was diverted back into its original bed. Most likely, this occurred due to artificial opening of the river dam. In consequence, Lago di Vedana was isolated from an open and minerogenic to an endorheic and carbonaceous lacustrine system. After a monastery was established nearby in AD 1457, a second eutrophication process was initiated due to intensified land use linked with deforestation. Only in the eighteenth and nineteenth centuries, deposition of organic matter decreased coinciding with climatic (Little Ice Age) and cultural changes. Conversational measures are the likely reasons for a trend towards less eutrophic conditions since AD 1950.
    Description: Universität Bremen (1013)
    Description: https://doi.org/10.1594/PANGAEA.937090
    Keywords: ddc:551.3 ; Landslide ; XRF scanning ; Geochemistry ; Soil erosion ; Cultural eutrophication ; Late Holocene
    Language: English
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    Determination of phase relations of the olivine–ahrensite transition in the Mg2SiO4–Fe2SiO4 system at 1740 K using modern multi-anvil techniques (2021)
    Chanyshev, Artem ; Bondar, Dmitry ; Fei, Hongzhan ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-04
    Description: The phase relations of iron-rich olivine and its high-pressure polymorphs are important for planetary science and meteoritics because these minerals are the main constituents of terrestrial mantles and meteorites. The olivine–ahrensite binary loop was previously determined by thermochemical calculations in combination with high-pressure experiments; however, the transition pressures contained significant uncertainties. Here we determined the binary loop of the olivine–ahrensite transition in the (Mg,Fe)2SiO4 system at 1740 K in the pressure range of 7.5–11.2 GPa using a multi-anvil apparatus with the pressure determined using in situ X-ray diffraction, compositional analysis of quenched run products, and thermochemical calculation. Based on the determined binary loop, a user-friendly software was developed to calculate pressure from the coexisting olivine and ahrensite compositions. The software is used to estimate the shock conditions of several L6-type chondrites. The obtained olivine–ahrensite phase relations can also be applied for precise in-house multi-anvil pressure calibration at high temperatures.
    Description: BMBF
    Description: H2020 European Research Council http://dx.doi.org/10.13039/100010663
    Description: Deutsches Elektronen-Synchrotron (DESY) (4201)
    Keywords: ddc:549 ; Experimental ; Olivine ; Ahrensite ; Phase transition ; Thermobarometry ; Meteorites
    Language: English
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  • 69
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    NPP-ID: Non-Pollen Palynomorph Image Database as a research and educational platform (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-04
    Description: Non-pollen palynomorphs (NPPs) form a large group of biological objects found in palynological slides besides pollen grains. This includes various remains of algae and fungi, shells, resting stages and eggs of invertebrates, among others. Publications of NPP-types started in the 1970s with studies of BvG and colleagues, and large numbers of new types continue to be published every year. For an overview of this diverse world of “extra fossils”, we created the Non-Pollen Palynomorph Image Database (NPP-ID) to gather NPP knowledge, structured by acronyms and known taxonomy to assist identification and palaeoecological interpretation (https://nonpollenpalynomorphs.tsu.ru/). An integral part is a database of illustrations, descriptions and ecological background of NPPs. While numerical data are routinely stored in open access repositories, the NPP-ID enables the definitions, identification and interpretation of the NPP taxa to be shared. The NPP-ID operates as an open research project aiming to provide open access to descriptions and illustrations of NPPs. However, due to publication rights, access to some original images is restricted and registration by users is required. We encourage palynologists to contribute to the further growth of the database by uploading their own microphotographs or drawings under an open access license. Contributors will be acknowledged by co-authorship in publications on updates of the NPP-ID.
    Description: Российский Фонд Фундаментальных Исследований (РФФИ) http://dx.doi.org/10.13039/501100002261
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Georg-August-Universität Göttingen (1018)
    Description: http://nonpollenpalynomorphs.tsu.ru/
    Keywords: ddc:561 ; Palynology ; Fungal remains ; Algal remains ; Unknown palynomorphs ; Identification tool
    Language: English
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  • 70
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    Evolution of the Lower Permian Rochlitz volcanic system, Eastern Germany: reconstruction of an intra-continental supereruption (2021)
    Hübner, Marcel ; Breitkreuz, Christoph ; Repstock, Alexander ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-04
    Description: Extensional tectonics in the Late Paleozoic Central Europe was accompanied by rift magmatism that triggered voluminous intracontinental caldera-forming eruptions. Among these, the Lower Permian Rochlitz Volcanic System (RVS) in the North Saxon Volcanic Complex (Eastern Germany, Saxony) represents a supereruption (VEI 8, estimated volume of 1056 km3) of monotonous rhyolites followed by monotonous intermediates. Mapping, petrography, whole-rock geochemistry along with mineral chemistry and oxygen isotopes in zircon display its complex eruption history and magma evolution. Crystal-rich (〉 35 vol%), rhyolitic Rochlitz-α Ignimbrite with strong to moderate welding compaction erupted in the climactic stage after reheating of the magma by basaltic injections. Due to magma mixing, low-volume trachydacitic-to-rhyolitic Rochlitz-β Ignimbrite succeeded, characterized by high Ti and Zr-values and zircon with mantle δ18O. Randomly oriented, sub-horizontally bedded fiamme, and NW–SE striking subvolcanic bodies and faults suggest pyroclastic fountaining along NW–SE-oriented fissures as the dominant eruption style. Intrusion of the Leisnig and the Grimma Laccoliths caused resurgence of the Rochlitz caldera forming several peripheral subbasins. In the post-climactic stage, these were filled with lava complexes, ignimbrites and alluvial to lacustrine sediments. Significant Nb and Ta anomalies and high Nb/Ta ratios (11.8–17.9) display a high degree of crustal contamination for the melts of the RVS. Based on homogenous petrographic and geochemical composition along with a narrow range of δ18O in zircon Rochlitz-α Ignimbrite were classified as monotonous rhyolites. For the Rochlitz-β Ignimbrites, underplating and mixing with basic melts are indicated by Mg-rich annite–siderophyllite and δ18O 〈 6.0 in zircon. The wide spectrum of δ18O on zircon suggests an incomplete mixing process during the formation of monotonous intermediates in the RVS.
    Description: Technische Universität Bergakademie Freiberg (3135)
    Keywords: ddc:552.2 ; Monotonous rhyolites ; Monotonous intermediates ; Magma mixing ; Ti-in-biotite thermobarometer ; δ18O in zircon ; VEI 8 fissure eruption
    Language: English
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  • 71
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    Comparisons of CODE and CNES/CLS GPS satellite bias products and applications in Sentinel-3 satellite precise orbit determination (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-04
    Description: To resolve undifferenced GNSS phase ambiguities, dedicated satellite products are needed, such as satellite orbits, clock offsets and biases. The International GNSS Service CNES/CLS analysis center provides satellite (HMW) Hatch-Melbourne-Wübbena bias and dedicated satellite clock products (including satellite phase bias), while the CODE analysis center provides satellite OSB (observable-specific-bias) and integer clock products. The CNES/CLS GPS satellite HMW bias products are determined by the Hatch-Melbourne-Wübbena (HMW) linear combination and aggregate both code (C1W, C2W) and phase (L1W, L2W) biases. By forming the HMW linear combination of CODE OSB corrections on the same signals, we compare CODE satellite HMW biases to those from CNES/CLS. The fractional part of GPS satellite HMW biases from both analysis centers are very close to each other, with a mean Root-Mean-Square (RMS) of differences of 0.01 wide-lane cycles. A direct comparison of satellite narrow-lane biases is not easily possible since satellite narrow-lane biases are correlated with satellite orbit and clock products, as well as with integer wide-lane ambiguities. Moreover, CNES/CLS provides no satellite narrow-lane biases but incorporates them into satellite clock offsets. Therefore, we compute differences of GPS satellite orbits, clock offsets, integer wide-lane ambiguities and narrow-lane biases (only for CODE products) between CODE and CNES/CLS products. The total difference of these terms for each satellite represents the difference of the narrow-lane bias by subtracting certain integer narrow-lane cycles. We call this total difference “narrow-lane” bias difference. We find that 3% of the narrow-lane biases from these two analysis centers during the experimental time period have differences larger than 0.05 narrow-lane cycles. In fact, this is mainly caused by one Block IIA satellite since satellite clock offsets of the IIA satellite cannot be well determined during eclipsing seasons. To show the application of both types of GPS products, we apply them for Sentinel-3 satellite orbit determination. The wide-lane fixing rates using both products are more than 98%, while the narrow-lane fixing rates are more than 95%. Ambiguity-fixed Sentinel-3 satellite orbits show clear improvement over float solutions. RMS of 6-h orbit overlaps improves by about a factor of two. Also, we observe similar improvements by comparing our Sentinel-3 orbit solutions to the external combined products. Standard deviation value of Satellite Laser Ranging residuals is reduced by more than 10% for Sentinel-3A and more than 15% for Sentinel-3B satellite by fixing ambiguities to integer values.
    Description: Technische Universität München (1025)
    Keywords: ddc:526 ; Bias comparison ; Sentinel-3A/B ; Undifferenced ambiguity resolution ; CNES/CLS ; CODE
    Language: English
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  • 72
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    Constraints of the durability of inorganic and organic consolidants for marble (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-04
    Description: In the present study, 5 different consolidants were tested on 5 different marble varieties preliminarily subjected to artificial weathering, to evaluate their consolidating effectiveness and thermal behavior after consolidation, in terms of residual strain after heating–cooling cycles in dry and wet condition and tendency to bowing. Treatments based on ethyl silicate, with and without a coupling agent to improve the performance on calcitic substrates, exhibited modest increases in cohesion after consolidation, as well as an increase in the thermal expansion coefficient and some residual strain at the end of the cycles. Paraloid B72 caused minor alterations in the pore system and limited increases in ultrasonic velocity, while the so-called “acrylic total impregnation” method led to an almost complete pore filling and significant improvements in cohesion. While the latter samples apparently resisted well to heating–cooling cycles, samples impregnated with Paraloid B72 exhibited progressive collapse of the fabric, likely due to the low glass transition temperature of Paraloid B72. Ammonium phosphate proved to be able to significantly improve marble cohesion and led to lower residual strain after heating–cooling cycles, compared to untreated marble. The DAP-treatment also exhibited a significant ability to slow down further bowing of already bowed slabs and to prevent bowing of initially planar slabs.
    Description: BMBF
    Description: Georg-August-Universität Göttingen (1018)
    Keywords: ddc:552.4 ; Marble ; Consolidation ; Ethyl silicate ; Polymethyl methacrylate ; Thermal expansion coefficient ; Thermal weathering ; Residual strain ; Bowing ; Hydroxyapatite
    Language: English
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  • 73
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    Review of Devonian-Carboniferous Boundary sections in the Rhenish Slate Mountains (Germany) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-20
    Description: Thirty Devonian-Carboniferous Boundary sections of the Rhenish Slate Mountains and adjacent subsurface areas are reviewed with respect to litho-, event, conodont, ammonoid, sequence, and chemostratigraphy. In the interval from the base of the uppermost Famennian (Wocklum Beds, Wocklumian) to the base of the middle Tournaisian (base Lower Alum Shale), 11 conodont and 16 ammonoid (sub)zones are distinguished. The terminology of the Hangenberg Crisis Interval is refined, with an overall regressive Crisis Prelude below the main Hangenberg Extinction, which defines the base of the transgressive Lower Crisis Interval (Hangenberg Black Shale). The glacigenic and regressive Middle Crisis Interval (Hangenberg Shale/Sandstone) is followed by the overall transgressive Upper Crisis Interval that can be subdivided into three parts (I to III) with the help of conodont stratigraphy (upper costatus-kockeli Interregnum = upper ckI, Protognathodus kockeli Zone, and lower part of Siphonodella (Eosiphonodella) sulcata s.l./Pr. kuehni Zone). Protognathodus kockeli includes currently a wide range of forms, which variabilities and precise ranges need to be established before a precise GSSP level should be selected. Returning to its original definition, the former Upper duplicata Zone is re-named as Siphonodella (S.) mehli Zone. It replaces the S. (S.) jii Zone, which is hampered by taxonomic complications. The S. (S.) quadruplicata Zone of Ji (1985) is hardly supported by Rhenish data. The entry of typical S. (S.) lobata (M1) characterises an upper subdivision (subzone) of the S. (S.) sandbergi Zone; the new S. (S.) lobata M2 enters much earlier within the S. (S.) mehli Zone. The ammonoid-defined base of the Wocklum-Stufe (Upper Devonian = UD VI) begins with the Linguaclymenia similis Zone (UD VI-A1). The oldest S. (Eosiphonodella) enter within the Muessenbiaergia bisulcata Zone (UD VI-A2). The traditional Parawocklumeria paradoxa Zone of Schindewolf (1937) is divided into successive P. paprothae (VI-C1), P. paradoxa (VI-C2), and Mayneoceras nucleus (VI-C3) Subzones. In the lower Tournaisian (Lower Carboniferous = LC I), the Gattendorfia subinvoluta Zone is subdivided into G. subinvoluta (LC I-A2) and “Eocanites” nodosus (LC I-A3) Subzones. The Paprothites dorsoplanus Zone (LC I-B) can be divided into Pap. dorsoplanus (LC I-B1) and Paragattendorfia sphaeroides (LC I-B2) Subzones. Potential subdivisions of the Pseudarietites westfalicus (LC I-C) and Parag. patens Zones (LC I-D) are less distinctive. The unfossiliferous or argillaceous upper part of the Hangenberg Limestone and the overlying Lower Alum Shale Event Interval remain regionally unzoned for ammonoids.
    Description: Westfälische Wilhelms-Universität Münster (1056)
    Keywords: ddc:560 ; Rhenish Massif ; Devonian-Carboniferous Boundary ; Lithostratigraphy ; Biostratigraphy ; Hangenberg Crisis ; Carbon isotopes
    Language: English
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  • 74
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    Late Devonian (Famennian) to Carboniferous (Mississippian-Pennsylvanian) conodonts from the Anarak section, Central Iran (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-20
    Description: A relatively complete conodont record from Famennian to the Mississippian/Pennsylvanian boundary was investigated in the Anarak section, Central Iran. The studied interval belongs to the Bahram, Shishtu, Ghaleh and Absheni formations. The Famennian part of the section (Bahram Formation) ranges from the Palmatolepis triangularis Zone into the Bispathodus ultimus Zone. Not all conodont zones could be defined due to the lack of indicative species. Furthermore, it seems likely that a hiatus occurs around the Devonian/Carboniferous (D/C) boundary (most probably from the Siphonodella praesulcata to the ?Siphonodella sulcata–early Siphonodella crenulata conodont zones) based on the lack of stratigraphically important conodonts as well as on sedimentological criteria. The lack of representative siphonodellids and protognathodids at the base of the Mississippian prevents detailed stratigraphic position of the D/C boundary. Lower Carboniferous (Mississippian) rocks are characterized by red nodular limestone which is unique in comparison with other studied sections of the same age in Central Iran. Within the studied section, we could define the Mississippian/Pennsylvanian boundary. The mid-Carboniferous boundary was defined by the occurrence of Declinognathus noduliferus s.l. Conodont biofacies changes (Mississippian genera Gnathodus and Lochriea have been replaced by Pennsylvanian genera Declinognathus and Idiognathodus) are recognized in this section as well.
    Description: Ministry of Science Research and Technology (IR)
    Keywords: ddc:562 ; Biostratigraphy ; Devonian ; Carboniferous ; Anarak ; Central Iran
    Language: English
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  • 75
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    A partial skeleton of Septencoracias from the early Eocene London Clay reveals derived features of bee-eaters (Meropidae) in a putative stem group roller (Aves, Coracii) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-20
    Description: A partial skeleton of the putative stem group roller Septencoracias is described from the early Eocene London Clay of Walton-on-the-Naze (Essex, UK). With an age of about 55 million years, the bones represent one of the earliest fossil records of a coraciiform bird. The new fossil reveals that the proximal pedal phalanges of the three anterior toes of Septencoracias exhibit markedly widened distal ends. This distinctive trait is not found in other representatives of the Coracii, but occurs in the Meropidae (bee-eaters). The quadrate likewise exhibit a derived characteristic of the Meropidae, and the beak is narrower than in rollers. These previously unnoticed features are of particular interest, because the Meropidae result as the sister taxon of the Coracii in sequence-based analyses. Calibrated molecular data suggest that the divergence between the Coracii and the Meropidae occurred at 55.6 Ma, with the new fossil being only slightly younger than this date. However, phylogenetic analyses recovered Septencoracias within the Coracii, so that the derived features shared with the Meropidae most likely are either plesiomorphic and were lost in the Coracii, or they represent parallelisms that evolved convergently in Septencoracias and the Meropidae. In any case, these traits suggest that Septencoracias differed from extant rollers in its ecological preferences and foraging mode.
    Description: Senckenberg Forschungsinstitut und Naturmuseum Frankfurt (3507)
    Keywords: ddc:568 ; Coracii ; Fossil birds ; Walton-on-the-Naze ; Ypresian
    Language: English
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  • 76
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    The early Cenomanian crippsi Event at Lüneburg (Germany): palaeontological and stratigraphical significance of a widespread Late Cretaceous bioevent (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-20
    Description: The early Cenomanian crippsi Event comprises a 1–3-m-thick interval characterised by mass occurrences of the early Cenomanian inoceramid Gnesioceramus crippsi, identified in the uppermost Sharpeiceras schlueteri Subzone (lower lower Cenomanian Mantelliceras mantelli Zone), below an interregional sequence boundary (SB Ce 1). At Lüneburg, the event is characterised by densely packed, very large, disc-like valves of G. crippsi. Taphonomy as well as bio- and microfacies suggest an event formation in a deeper shelf setting below the storm-wave base as primary biogenic concentration, the inoceramids living as recumbent forms on a soft substrate in dense populations. When tracked between basins, the stratigraphic pattern of the crippsi Event suggests a moderately prolonged phase (〈 100 kyr) of increased shell production with rapid deposition aiding in preserving the shell-rich event strata. Towards the basin margins, it grades into storm wave-reworked bioclastic concentrations. The crippsi Event formed by an interregional population bloom and provides, as an proliferation epibole, an important marker for intra- and interbasinal correlation. The first record of G. mowriensis within the crippsi Event at Lüneburg, hitherto endemic to the US Western Interior Seaway, and the occurrence of the ammonite Metengonoceras teigenense, likewise an endemic North American faunal element, from the level of the crippsi Event in northern France indicate faunal exchange between the New and Old worlds during the early Cenomanian. This faunal dispersal and contemporaneous occurrence of warm-water biofacies in Western Europe during the early Cenomanian is explained by the existence of a perpetual NE-directed current transporting warm surface waters from the Gulf of Mexico towards Europe. The occurrence of short-lived M. teigenense in France allows for the calibration of the uppermost schlueteri Subzone of the mantelli Zone in Europe to the lowermost Neogastroplites muelleri Zone in North America and to assign an age of ~ 98.6–98.7 Ma to the crippsi Event.
    Description: Senckenberg Naturhistorische Sammlungen Dresden (3507)
    Keywords: ddc:560 ; Upper Cretaceous ; Proliferation epibole ; Taphonomy ; Palaeo(bio)geography ; Correlation
    Language: English
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  • 77
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    Lithium and Sr isotopic composition of salar deposits in the Central Andes across space and time: the Salar de Pozuelos, Argentina (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: The Central Andes of South America host the largest known lithium resources in a confined area, but the primary lithium sources of the salar deposits and the mobilisation process of lithium are still a matter of speculation. Chemical weathering at or near the surface and leaching in hydrothermal systems of the active magmatic arc are considered the two main mechanisms of Li extraction from the source rock. The lithium and strontium isotope composition of typical salar deposits offer insights into the processes on how Li brine deposits in Andean evaporites are formed. Data from the Salar de Pozuelos indicate near-surface chemical weathering in a cold and dry climate as the dominant mobilisation process of Li, with evaporation being responsible for the enrichment. The Cenozoic ignimbrites are the favoured source rock for the Li, with subordinate additions from the Palaeozoic basement. The identification of the source rocks is supported by radiogenic Nd and Pb and stable B isotope data from salar deposits. A comparison with other Li brine and salt deposits in the Altiplano-Puna Plateau and its western foothills places the Salar de Pozuelos as an endmember of Li solubilisation by chemical weathering with only minor hydrothermal mobilisation of Li.
    Description: Universität Bremen (1013)
    Keywords: ddc:553.6 ; Central Andes ; Salar deposits ; Lithium isotopes ; Lithium deposits
    Language: English
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  • 78
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    The formation of (Ni-Co-Sb)-Ag-As ore shoots in hydrothermal galena-sphalerite-fluorite veins (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: Unusual hydrothermal native As-sulfide ± native Ag ± arsenide ± antimonide ± sulfosalt ore shoots and their co-genetic sulfide-fluorite-barite-quartz host veins, which are common in the region and in whole Central Europe, were investigated at three localities in the Schwarzwald, SW Germany, to understand the physico-chemical processes governing the change from a normal (= common) hydrothermal to an exceptional ore shoot regime. Based on fluid inclusions, the formation of the gangue minerals is the result of binary mixing between a NaCl-rich brine and a CaCl2-rich brine (both ~ 20 wt% NaCl aq.). This mixing correlation, major and minor fluid composition, formation temperature (~ 150 °C), and δ34S signature are identical (within error) in ore shoots and host veins. Thermodynamic modeling indicates that ore shoot formation must have resulted from a change in redox conditions by a local influx of a volumetrically minor reducing agent, probably hydrocarbons. The elemental content and the mineralogy of each ore shoot locality (Ag-As-rich: Münstertal; Ag–Ni-As-rich: Urberg; Ag–Ni-As-Sb-rich: Wieden) reflect the metal content of the binary mixed fluid, while mineral textures, successions, and assemblages are thermodynamically and, regarding sulfur, kinetically controlled. The formation of vein and ore shoot sulfides requires an addition of sulfide, most probably from the sulfide-bearing host rocks, because thermodynamic and kinetic reasons suggest that the two major vein-forming and metal-bearing fluids are not the source of the sulfur. The final ore shoot textures are influenced by later hydrothermal remobilization processes of As and Ag. This results in a number of sulfosalts, mostly proustite-pyrargyrite. Interestingly, the greater thermodynamic stability of Sb-endmember sulfosalts enables them to form even in As-dominated fluid systems.
    Description: Eberhard Karls Universität Tübingen (1020)
    Keywords: ddc:553.4 ; Five-element association ; Native arsenic ; Hydrothermal ore shoot ; Reduction ; Native silver
    Language: English
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  • 79
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    Evolution of a hydrothermal ore-forming system recorded by sulfide mineral chemistry: a case study from the Plaka Pb–Zn–Ag Deposit, Lavrion, Greece (2021)
    Frenzel, Max ; Voudouris, Panagiotis ; Cook, Nigel J. ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: Laser ablation-inductively coupled plasma-mass spectrometry and electron-probe microanalysis were used to investigate the trace-element contents of sphalerite, chalcopyrite and pyrite from the Plaka Pb–Zn–Ag deposit. Using petrographic observations, the analytical results could be linked to the temporal evolution of the Plaka ore-forming system. Sphalerite chemistry reliably records the temperature and fS2 evolution of the system, with estimated formation temperatures reproducing the microthermometric results from previous fluid-inclusion studies. Chalcopyrite chemistry also shows systematic variations over time, particularly for Cd, Co, Ge, In, Sn and Zn concentrations. Measurable pyrite was only found in association with early high-temperature mineralisation, and no clear trends could therefore be identified. We note, however, that As and Se contents in pyrite are consistent with formation temperatures estimated from co-existing sphalerite. Statistical analysis of the sphalerite data allowed us to identify the dominant geological controls on its trace-element content. The three investigated factors temperature, fS2, and sample location account for 〉 80% of the observed variance in Mn, Fe, Co, Ga, Ge, In, Sb and Hg concentrations, and 〉 60% of the observed variance in Cd and Sn concentrations. Only for Cu and Ag concentrations is the explained variance 〈 50%. A similarly detailed analysis was not possible for chalcopyrite and pyrite. Nevertheless, comparison of the results for all three investigated minerals indicates that there are some systematic variations across the deposit which may be explained by local differences in fluid composition.
    Description: Deutscher Akademischer Austauschdienst http://dx.doi.org/10.13039/501100001655
    Description: Helmholtz-Zentrum Dresden - Rossendorf e. V. (4213)
    Keywords: ddc:553.4 ; Trace elements ; LA-ICP-MS ; Sphalerite ; Chalcopyrite ; Pyrite
    Language: English
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  • 80
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    Differentiating between hydrothermal and diagenetic carbonate using rare earth element and yttrium (REE+Y) geochemistry: a case study from the Paleoproterozoic George Fisher massive sulfide Zn deposit, Mount Isa, Australia (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: Carbonate minerals are ubiquitous in most sediment-hosted mineral deposits. These deposits can contain a variety of carbonate types with complex paragenetic relationships. When normalized to chondritic values (CN), rare-earth elements and yttrium (REE+YCN) can be used to constrain fluid chemistry and fluid-rock interaction processes in both low- and high-temperature settings. Unlike other phases (e.g., pyrite), the application of in situ laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS) data to the differentiation of pre-ore and hydrothermal carbonates remains relatively untested. To assess the potential applicability of carbonate in situ REE+Y data, we combined transmitted light and cathodoluminescence (CL) petrography with LA-ICP-MS analysis of carbonate mineral phases from (1) the Proterozoic George Fisher clastic dominated (CD-type) massive sulfide deposit and from (2) correlative, barren host rock lithologies (Urquhart Shale Formation). The REE+YCN composition of pre-ore calcite suggests it formed during diagenesis from diagenetic pore fluids derived from ferruginous, anoxic seawater. Hydrothermal and hydrothermally altered calcite and dolomite from George Fisher is generally more LREE depleted than the pre-ore calcite, whole-rock REE concentrations, and shale reference values. We suggest this is the result of hydrothermal alteration by saline Cl--rich mineralizing fluids. Furthermore, the presence of both positive and negative Eu/Eu* values in calcite and dolomite indicates that the mineralizing fluids were relatively hot (〉250°C) and cooled below 200–250°C during ore formation. This study confirms the hypothesis that in situ REE+Y data can be used to differentiate between pre-ore and hydrothermal carbonate and provide important constraints on the conditions of ore formation.
    Description: Helmholtz-Gemeinschaft http://dx.doi.org/10.13039/501100001656
    Description: https://doi.org/10.5880/GFZ.3.1.2020.005
    Keywords: ddc:553.4 ; CD-type massive sulfide deposit ; Rare earth elements ; Carbonate chemistry ; Proterozoic ; Mount Isa ; LA-ICP-MS
    Language: English
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  • 81
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    The influence of the Earth’s magnetic field on strapdown inertial gravimetry using Q-Flex accelerometers: static and dynamic experiments (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: In recent strapdown airborne and shipborne gravimetry campaigns with servo accelerometers of the widely used Q-Flex type, results have been impaired by heading-dependent measurement errors. This paper shows that the effect is, in all likelihood, caused by the sensitivity of the Q-Flex type sensor to the Earth’s magnetic field. In order to assess the influence of magnetic fields on the utilised strapdown IMU of the type iMAR iNAV-RQH-1003, the IMU has been exposed to various magnetic fields of known directions and intensities in a 3-D Helmholtz coil. Based on the results, a calibration function for the vertical accelerometer is developed. At the example of five shipborne and airborne campaigns, it is outlined that under specific circumstances the precision of the gravimetry results can be strongly improved using the magnetic calibration approach: The non-adjusted RMSE at repeated lines decreased from 1.19 to 0.26 mGal at a shipborne campaign at Lake Müritz, Germany. To the knowledge of the authors, a significant influence of the Earth’s magnetic field on strapdown inertial gravimetry is demonstrated for the first time.
    Description: Technische Universität Darmstadt (3139)
    Keywords: ddc:526 ; Gravimetry ; Strapdown ; Magnetic field ; Q-Flex ; IMU
    Language: English
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  • 82
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    Li-Co–Ni-Mn-(REE) veins of the Western Erzgebirge, Germany—a potential source of battery raw materials (2021)
    Burisch, Mathias ; Frenzel, Max ; Seibel, Henning ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: Situated in the western Erzgebirge metallogenetic province (Vogtland, Germany), the Eichigt prospect is associated with several quartz-Mn-Fe-oxyhydroxide veins that are exposed at surface. Bulk-rock geochemical assays of vein material yield high concentrations of Li (0.6–4.1 kg/t), Co (0.6–14.7 kg/t), and Ni (0.2–2.8 kg/t), as well as significant quantities of Mn, Cu, and light rare earth elements, a very unusual metal tenor closely resembling the mixture of raw materials needed for Li-ion battery production. This study reports on the results of a first detailed investigation of this rather unique polymetallic mineralization style, including detailed petrographic and mineralogical studies complemented by bulk rock geochemistry, electron microprobe analyses, and laser ablation inductively coupled mass spectrometry. The mineralized material comprises an oxide assemblage of goethite hematite, hollandite, and lithiophorite that together cement angular fragments of vein quartz. Lithiophorite is the predominant host of Li (3.6–11.1 kg/t), Co (2.5–54.5 kg/t), and Ni (0.2–8.9 kg/t); Cu is contained in similar amounts in hollandite and lithiophorite whereas light rare earth elements (LREE) are mainly hosted in microcrystalline rhabdophane and florencite, which are finely intergrown with the Mn-Fe-oxyhydroxides. 40Ar/39Ar ages (~ 40–34 Ma) of coronadite group minerals coincide with tectonic activity related to the Cenozoic Eger Graben rifting. A low-temperature hydrothermal overprint of pre-existing base metal sulfide-quartz mineralization on fault structures that were reactivated during continental rifting is proposed as the most likely origin of the polymetallic oxyhydroxide mineralization at Eichigt. However, tectonically enhanced deep-reaching fracture-controlled supergene weathering cannot be completely ruled out as the origin of the mineralization.
    Description: Lithium Australia
    Description: European Social Fund http://dx.doi.org/10.13039/501100004895
    Description: Technische Universität Bergakademie Freiberg (3135)
    Keywords: ddc:553.4 ; Lithiophorite ; Coronadite group ; Hollandite ; Cryptomelane ; 40Ar/39Ar geochronology ; Trace elements ; Lithium ; Manganese ; Cobalt ; Exploration ; Raw materials
    Language: English
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  • 83
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    Sentinel-6A precise orbit determination using a combined GPS/Galileo receiver (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: The Sentinel-6 (or Jason-CS) altimetry mission provides a long-term extension of the Topex and Jason-1/2/3 missions for ocean surface topography monitoring. Analysis of altimeter data relies on highly-accurate knowledge of the orbital position and requires radial RMS orbit errors of less than 1.5 cm. For precise orbit determination (POD), the Sentinel-6A spacecraft is equipped with a dual-constellation GNSS receiver. We present the results of Sentinel-6A POD solutions for the first 6 months since launch and demonstrate a 1-cm consistency of ambiguity-fixed GPS-only and Galileo-only solutions with the dual-constellation product. A similar performance (1.3 cm 3D RMS) is achieved in the comparison of kinematic and reduced-dynamic orbits. While Galileo measurements exhibit 30–50% smaller RMS errors than those of GPS, the POD benefits most from the availability of an increased number of satellites in the combined dual-frequency solution. Considering obvious uncertainties in the pre-mission calibration of the GNSS receiver antenna, an independent inflight calibration of the phase centers for GPS and Galileo signal frequencies is required. As such, Galileo observations cannot provide independent scale information and the estimated orbital height is ultimately driven by the employed forces models and knowledge of the center-of-mass location within the spacecraft. Using satellite laser ranging (SLR) from selected high-performance stations, a better than 1 cm RMS consistency of SLR normal points with the GNSS-based orbits is obtained, which further improves to 6 mm RMS when adjusting site-specific corrections to station positions and ranging biases. For the radial orbit component, a bias of less than 1 mm is found from the SLR analysis relative to the mean height of 13 high-performance SLR stations. Overall, the reduced-dynamic orbit determination based on GPS and Galileo tracking is considered to readily meet the altimetry-related Sentinel-6 mission needs for RMS height errors of less than 1.5 cm.
    Description: Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (4202)
    Keywords: ddc:526 ; Sentinel-6 ; Jason-CS ; Single-receiver ambiguity fixing ; Precise orbit determination ; GPS ; Galileo ; SLR ; Altimetry
    Language: English
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  • 84
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    Galileo precise orbit determination with optical two-way links (OTWL): a continuous wave laser ranging and time transfer concept (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: In this simulation study we analyze the benefit of ground-space optical two-way links (OTWL) for Galileo precise orbit determination (POD). OTWL is a concept based on continuous wave laser ranging and time transfer with modulated signals from and to ground stations. The measurements are in addition to Global Navigation Satellite System (GNSS) observations. We simulate the measurements with regard to 16 Galileo Sensor Stations. In the simulation study we assume that the whole Galileo satellite constellation is equipped with terminals for OTWL. Using OTWL together with Galileo L-band, in comparison with an orbit solution calculated with L-band-only, demonstrates the advantage of combining two ranging techniques with different influences of systematic errors. The two-way link allows a station and satellite clock synchronization. Furthermore, we compare the ground-space concept with the satellite-to-satellite counterpart known as optical two-way inter-satellite links (OISL). The advantage of OTWL is the connection between the satellite system and the solid Earth as well as the possibility to synchronize the satellite clocks and the ground station clocks. The full network, using all three observation types in combination is simulated as well. The possibility to estimate additional solar radiation pressure (SRP) parameters within these combinations is a clear benefit of these additional links. We paid great attention to simulate systematic effects of all observation techniques as realistically as possible. For L-band these are measurement noise, tropospheric delays, phase center variation of receiver and transmitter antennas, constant and variable biases as well as multipath. For optical links we simulated colored and distance-dependent noise, offsets due to the link repeatability and offsets related to the equipment calibration quality. In addition, we added a troposphere error for the OTWL measurements. We discuss the influence on the formal orbit uncertainties and the effects of the systematic errors. Restrictions due to weather conditions are addressed as well. OTWL is synergetic with the other measurement techniques like OISL and can be used for data transfer and communication, respectively.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Technische Universität München (1025)
    Keywords: ddc:526 ; Galileo ; POD ; Optical two-way link ; Inter-satellite link
    Language: English
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  • 85
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    A partition-enhanced least-squares collocation approach (PE-LSC) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: We present a partition-enhanced least-squares collocation (PE-LSC) which comprises several modifications to the classical LSC method. It is our goal to circumvent various problems of the practical application of LSC. While these investigations are focused on the modeling of the exterior gravity field the elaborated methods can also be used in other applications. One of the main drawbacks and current limitations of LSC is its high computational cost which grows cubically with the number of observation points. A common way to mitigate this problem is to tile the target area into sub-regions and solve each tile individually. This procedure assumes a certain locality of the LSC kernel functions which is generally not given and, therefore, results in fringe effects. To avoid this, it is proposed to localize the LSC kernels such that locality is preserved, and the estimated variances are not notably increased in comparison with the classical LSC method. Using global covariance models involves the calculation of a large number of Legendre polynomials which is usually a time-consuming task. Hence, to accelerate the creation of the covariance matrices, as an intermediate step we pre-calculate the covariance function on a two-dimensional grid of isotropic coordinates. Based on this grid, and under the assumption that the covariances are sufficiently smooth, the final covariance matrices are then obtained by a simple and fast interpolation algorithm. Applying the generalized multi-variate chain rule, also cross-covariance matrices among arbitrary linear spherical harmonic functionals can be obtained by this technique. Together with some further minor alterations these modifications are implemented in the PE-LSC method. The new PE-LSC is tested using selected data sets in Antarctica where altogether more than 800,000 observations are available for processing. In this case, PE-LSC yields a speed-up of computation time by a factor of about 55 (i.e., the computation needs only hours instead of weeks) in comparison with the classical unpartitioned LSC. Likewise, the memory requirement is reduced by a factor of about 360 (i.e., allocating memory in the order of GB instead of TB).
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: Technische Universität München (1025)
    Keywords: ddc:526 ; Gravity field ; Least squares collocation (LSC) ; Covariance function ; Data combination ; Prediction ; Antarctica
    Language: English
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  • 86
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    Modeling ocean-induced rapid Earth rotation variations: an update (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: We revisit the problem of modeling the ocean’s contribution to rapid, non-tidal Earth rotation variations at periods of 2–120 days. Estimates of oceanic angular momentum (OAM, 2007–2011) are drawn from a suite of established circulation models and new numerical simulations, whose finest configuration is on a 1⁄ 6◦ grid. We show that the OAM product by the Earth System Modeling Group at GeoForschungsZentrum Potsdam has spurious short period variance in its equatorial motion terms, rendering the series a poor choice for describing oceanic signals in polar motion on time scales of less than ∼2 weeks. Accounting for OAM in rotation budgets from other models typically reduces the variance of atmosphere-corrected geodetic excitation by ∼54% for deconvolved polar motion and by ∼60% for length-of-day. Use of OAM from the 1⁄ 6◦ model does provide for an additional reduction in residual variance such that the combined oceanic–atmospheric effect explains as much as 84% of the polar motion excitation at periods 〈 120 days. Employing statistical analysis and bottom pressure changes from daily Gravity Recovery and Climate Experiment solutions, we highlight the tendency of ocean models run at a 1◦ grid spacing to misrepresent topographically constrained dynamics in some deep basins of the Southern Ocean, which has adverse effects on OAM estimates taken along the 90◦ meridian. Higher model resolution thus emerges as a sensible target for improving the oceanic component in broader efforts of Earth system modeling for geodetic purposes.
    Description: Austrian Science Fund http://dx.doi.org/10.13039/501100002428
    Description: National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104
    Description: https://isdc.gfz-potsdam.de/ggfc-oceans/
    Description: https://doi.org/10.5281/zenodo.4707150
    Description: http://rz-vm115.gfz-potsdam.de:8080/repository/
    Description: https://ifg.tugraz.at/ITSG-Grace2018
    Description: ftp://isdcftp.gfz-potsdam.de/grace/Level-1B/GFZ/AOD/RL06/
    Description: https://ecco-group.org/products-ECCO-V4r4.htm
    Keywords: ddc:550.2 ; Earth rotation ; Geophysical fluids ; Excitation ; Ocean bottom pressure
    Language: English
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    Strategy for the realisation of the International Height Reference System (IHRS) (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: In 2015, the International Association of Geodesy defined the International Height Reference System (IHRS) as the conventional gravity field-related global height system. The IHRS is a geopotential reference system co-rotating with the Earth. Coordinates of points or objects close to or on the Earth’s surface are given by geopotential numbers C(P) referring to an equipotential surface defined by the conventional value W0 = 62,636,853.4 m2 s−2, and geocentric Cartesian coordinates X referring to the International Terrestrial Reference System (ITRS). Current efforts concentrate on an accurate, consistent, and well-defined realisation of the IHRS to provide an international standard for the precise determination of physical coordinates worldwide. Accordingly, this study focuses on the strategy for the realisation of the IHRS; i.e. the establishment of the International Height Reference Frame (IHRF). Four main aspects are considered: (1) methods for the determination of IHRF physical coordinates; (2) standards and conventions needed to ensure consistency between the definition and the realisation of the reference system; (3) criteria for the IHRF reference network design and station selection; and (4) operational infrastructure to guarantee a reliable and long-term sustainability of the IHRF. A highlight of this work is the evaluation of different approaches for the determination and accuracy assessment of IHRF coordinates based on the existing resources, namely (1) global gravity models of high resolution, (2) precise regional gravity field modelling, and (3) vertical datum unification of the local height systems into the IHRF. After a detailed discussion of the advantages, current limitations, and possibilities of improvement in the coordinate determination using these options, we define a strategy for the establishment of the IHRF including data requirements, a set of minimum standards/conventions for the determination of potential coordinates, a first IHRF reference network configuration, and a proposal to create a component of the International Gravity Field Service (IGFS) dedicated to the maintenance and servicing of the IHRS/IHRF.
    Description: https://www.ngs.noaa.gov/GRAV-D/data_ms05.shtml
    Keywords: ddc:526 ; International Height Reference System (IHRS) ; International Height Reference Frame (IHRF) ; World height system ; Global unified vertical reference system ; Geopotential height datum ; Permanent tide ; Tide systems ; The Colorado experiment
    Language: English
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  • 88
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    Estimating ambiguity fixed satellite orbit, integer clock and daily bias products for GPS L1/L2, L1/L5 and Galileo E1/E5a, E1/E5b signals (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: Ambiguity resolution of a single receiver is becoming more and more popular for precise GNSS (Global Navigation Satellite System) applications. To serve such an approach, dedicated satellite orbit, clock and bias products are needed. However, we need to be sure whether products based on specific frequencies and signals can be used when processing measurements of other frequencies and signals. For instance, for Galileo E5a frequency, some receivers track only the pilot signal (C5Q) while some track only the pilot-data signal (C5X). We cannot compute the differences between C5Q and C5X directly since these two signals are not tracked concurrently by any common receiver. As code measurements contribute equally as phase in the Melbourne-Wuebbena (MelWub) linear combination it is important to investigate whether C5Q and C5X can be mixed in a network to compute a common satellite MelWub bias product. By forming two network clusters tracking Q and X signals, respectively, we confirm that GPS C5Q and C5X signals cannot be mixed together. Because the bias differences between GPS C5Q and C5X can be more than half of one wide-lane cycle. Whereas, mixing of C5Q and C5X signals for Galileo satellites is possible. The RMS of satellite MelWub bias differences between Q and X cluster is about 0.01 wide-lane cycles for both E1/E5a and E1/E5b frequencies. Furthermore, we develop procedures to compute satellite integer clock and narrow-lane bias products using individual dual-frequency types. Same as the finding from previous studies, GPS satellite clock differences between L1/L2 and L1/L5 estimates exist and show a periodical behavior, with a peak-to-peak amplitude of 0.7 ns after removing the daily mean difference of each satellite. For Galileo satellites, the maximum clock difference between E1/E5a and E1/E5b estimates after removing the mean value is 0.04 ns and the mean RMS of differences is 0.015 ns. This is at the same level as the noise of the carrier phase measurement in the ionosphere-free linear combination. Finally, we introduce all the estimated GPS and Galileo satellite products into PPP-AR (precise point positioning, ambiguity resolution) and Sentinel-3A satellite orbit determination. Ambiguity fixed solutions show clear improvement over float solutions. The repeatability of five ground-station coordinates show an improvement of more than 30% in the east direction when using both GPS and Galileo products. The Sentinel-3A satellite tracks only GPS L1/L2 measurements. The standard deviation (STD) of satellite laser ranging (SLR) residuals is reduced by about 10% when fixing ambiguity parameters to integer values.
    Description: Klinikum rechts der Isar der Technischen Universität München (8934)
    Keywords: ddc:526 ; Integer satellite clock ; Ambiguity resolution ; Daily code and phase biases ; GPS and Galileo signals ; Pilot and data
    Language: English
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  • 89
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    Multi-stage sulfide evolution of the Moran Ni sulfide ore, Kambalda, Western Australia: insights into the dynamics of ore forming processes of komatiite-hosted deposits (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: The Moran komatiite-hosted Ni sulfide deposit at Kambalda (Australia) is one of the better preserved orebodies at Kambalda. Its geochemical signature is used to investigate the evolution of the sulfide mineralization. The orebody has several parts, including a flanking segment where massive sulfides formed relatively early and a central portion in a 40-m-deep erosional embayment representing a later generation of massive and net-textured sulfides. Basal massive sulfides within the deep embayment vary systematically in their chalcophile element contents (Ni, PGE, Au, Te, As, Bi). Elements compatible in monosulfide solid solution (MSS) exhibit the highest concentration at the edge of the orebody (up to 4.3 ppm Ir + Os + Ru + Rh), whereas incompatible elements are most concentrated in the centre (up to 11.2 ppm Pt + Pd + Au). This difference in element distributions is explained by fractional crystallization of sulfide melt from the edge towards the centre. To explain the vertical movement of the residual fractionated melt, a new model of sulfide crystallization is proposed. A low-viscosity boundary layer containing incompatible elements is formed between MSS and sulfide melt. This melt propagates with the crystallization front towards the centre of the sulfide melt pool. Trace element variations in pentlandite (e.g. Co) and composite Co- and Bi-bearing arsenide-telluride grains suggest that during the final stages of crystallization, an immiscible Co-As-Te-Bi melt is formed.
    Description: Eberhard Karls Universität Tübingen (1020)
    Keywords: ddc:553.4 ; Kambalda ; Komatiite ; Magmatic sulfides ; Sulfide fractionation ; Boundary melt layer ; Sulfide trace elements
    Language: English
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    Status of the International Gravity Reference System and Frame (2021)
    Wziontek, Hartmut ; Bonvalot, Sylvain ; Falk, Reinhard ; [et al.]
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: The increasing importance of terrestrial gravimetry in monitoring global change processes, in providing a reference for satellite measurements and in applications in metrology necessitates a stable reference system reflecting the measurement accuracy achievable by modern gravimeters. Therefore, over the last decade, the International Association of Geodesy (IAG) has developed a system to achieve accurate, homogeneous, long-term global recording of Earth’s gravity, while taking advantage of the potential of today’s absolute gravity measurements. The current status of the International Gravity Reference System and Frame is presented as worked out by the IAG Joint Working Group 2.1.1 “Establishment of a global absolute gravity reference system” during the period 2015–2019. Here, the system is defined by the instantaneous acceleration of free-fall, expressed in the International System of Units (SI) and a set of conventional corrections for the time-independent components of gravity effects. The frame as the systems realization includes a set of conventional temporal gravity corrections which represent a uniform set of minimum requirements. Measurements with absolute gravimeters, the traceability of which is ensured by comparisons and monitoring at reference stations, provide the basis of the frame. A global set of such stations providing absolute gravity values at the microgal level is the backbone of the frame. Core stations with at least one available space geodetic technique will provide a link to the terrestrial reference frame. Expanded facilities enabling instrumental verification as well as repeated regional and additional comparisons will complement key comparisons at the level of the International Committee for Weights and Measures (CIPM) and ensure a common reference and the traceability to the SI. To make the gravity reference system accessible to any user and to replace the previous IGSN71 network, an infrastructure based on absolute gravity observations needs to be built up. This requires the support of national agencies, which are encouraged to establish compatible first order gravity networks and to provide information about existing absolute gravity observations.
    Description: Ministry of Education, Youth and Sports of the Czech Republic (MŠMT)
    Keywords: ddc:526 ; Gravity reference system and frame ; Absolute gravimeter
    Language: English
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    Benthic Foraminifera of the Agulhas Bank coastal shelf in the vicinity of Plettenberg Bay, South Africa: a reconnaissance survey (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: The study area is located on the inner Agulhas Bank around Plettenberg Bay, southern Cape Province, South Africa (Fig. 1). The Agulhas Bank is a transitional environment between the cold-temperate Benguela Current regime of the south-eastern South Atlantic and the warm-temperate Agulhas Current regime of the south-western Indian Ocean. Three distinct faunal assemblages (A, B and C) were identified in the study area. These are aligned in three consecutive, coast-parallel belts, assemblage A forming the inshore belt, assemblage C the offshore belt and assemblage B the in-between belt. Assemblage A is composed of Textularia-group individuals and Pararotalia sp., Cibicides lobatulus and Planorbulina mediterranensis. It occupies the nearshore belt up to 50 m water depth in sediments composed of very fine, fine and medium sands, with some coarse and very coarse sands. Assemblage B is composed of Bolivina cf. pseudopunctata, Cassidulina laevigata, Ammonia beccarii, Bolivina tortuosa and Bulimina elongata. It occupies water depths from 50–70 m, but may locally extend down to 90 m and, within the bay itself, upward to 20 m in fine and very fine sands containing some medium sand and mud. Assemblage C is dominated by Cassidulina laevigata, Bolivina cf. pseudopunctata, Bulimina elongata and Ammonia beccarii. In contrast to assemblage B which is dominated by B. cf. pseudopunctata, assemblage C is dominated by C. laevigata. Assemblage C is mainly confined to water depths of 70–100 m in sediments dominated by very fine sand (0.063–0.125 mm) containing some coarser sediment and mud. The distribution of the forams with respect to water depth, sediment composition and other environmental parameters suggests that it is mainly controlled by a combination of environmental parameters. No tangible relationship was found between the open shelf foraminifer communities and those of estuaries and lagoons along the South African coast.
    Description: Senckenberg Forschungsinstitut und Naturmuseum Frankfurt (3507)
    Keywords: ddc:561 ; Foraminifera ; coastal shelf ; Plettenberg Bay ; South Africa
    Language: English
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    Calibrating receiver-type-dependent wide-lane uncalibrated phase delay biases for PPP integer ambiguity resolution (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: Wide-lane (WL) uncalibrated phase delay (UPD) is usually derived from Melbourne–Wübbena (MW) linear combination and is a prerequisite in Global Navigation Satellite Systems (GNSS) precise point positioning (PPP) ambiguity resolution (AR). MW is a linear combination of pseudorange and phase, and the accuracy is limited by the larger pseudorange noise which is about one hundred times of the carrier phase noise. However, there exist inconsistent pseudorange biases which may have detrimental effect on the WL UPD estimation, and further degrade user-side ambiguity fixing. Currently, only the large part of pseudorange biases, e.g., the differential code bias (DCB), are available and corrected in PPP-AR, while the receiver-type-dependent biases have not yet been considered. Ignoring such kind of bias, which could be up to 20 cm, will cause the ambiguity fixing failure, or even worse, the incorrect ambiguity fixing. In this study, we demonstrate the receiver-type-dependent WL UPD biases and investigate their temporal and spatial stability, and further propose the method to precisely estimate these biases and apply the corrections to improve the user-side PPP-AR. Using a large data set of 1560 GNSS stations during a 30-day period, we demonstrate that the WL UPD deviations among different types of receivers can reach ± 0.3 cycles. It is also shown that such kind of deviations can be calibrated with a precision of about 0.03 cycles for all Global Positioning System (GPS) satellites. On the user side, ignoring the receiver-dependent UPD deviation can cause significant positioning error up to 10 cm. By correcting the deviations, the positioning performance can be improved by up to 50%, and the fixing rate can also be improved by 10%. This study demonstrates that for the precise and reliable PPP-AR, the receiver-dependent UPD deviations cannot be ignored and have to be handled.
    Description: China Scholarship Council http://dx.doi.org/10.13039/501100004543
    Description: Helmholtz-Zentrum Potsdam Deutsches GeoForschungsZentrum - GFZ (4217)
    Description: ftp://geodesy.noaa.gov/cors/rinex/
    Description: ftp://ftp.gfz-potsdam.de/GNSS/products/mgex/
    Description: ftp://ftp.aiub.unibe.ch/CODE/
    Keywords: ddc:526 ; Uncalibrated phase delay ; Precise point positioning ; Ambiguity resolution ; Receiver-type-dependent bias
    Language: English
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    Revisiting the light time correction in gravimetric missions like GRACE and GRACE follow-on (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-22
    Description: The gravity field maps of the satellite gravimetry missions Gravity Recovery and Climate Experiment (GRACE ) and GRACE Follow-On are derived by means of precise orbit determination. The key observation is the biased inter-satellite range, which is measured primarily by a K-Band Ranging system (KBR) in GRACE and GRACE Follow-On. The GRACE Follow-On satellites are additionally equipped with a Laser Ranging Interferometer (LRI), which provides measurements with lower noise compared to the KBR. The biased range of KBR and LRI needs to be converted for gravity field recovery into an instantaneous range, i.e. the biased Euclidean distance between the satellites’ center-of-mass at the same time. One contributor to the difference between measured and instantaneous range arises due to the nonzero travel time of electro-magnetic waves between the spacecraft. We revisit the calculation of the light time correction (LTC) from first principles considering general relativistic effects and state-of-the-art models of Earth’s potential field. The novel analytical expressions for the LTC of KBR and LRI can circumvent numerical limitations of the classical approach. The dependency of the LTC on geopotential models and on the parameterization is studied, and afterwards the results are compared against the LTC provided in the official datasets of GRACE and GRACE Follow-On. It is shown that the new approach has a significantly lower noise, well below the instrument noise of current instruments, especially relevant for the LRI, and even if used with kinematic orbit products. This allows calculating the LTC accurate enough even for the next generation of gravimetric missions.
    Description: Max-Planck-Gesellschaft http://dx.doi.org/10.13039/501100004189
    Description: National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809
    Keywords: ddc:526 ; GRACE follow-on ; Light time correction ; General relativity ; Laser interferomery ; K-band ranging
    Language: English
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    Mineralogical and geochemical investigation of megaspherulites from Argentina, Germany, and the USA (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-14
    Description: Textures and whole-rock chemistry, as well as mineral composition, were analyzed in megaspherulites (high-temperature crystallization domains [HTCDs]) that formed in different geographical and geotectonic contexts and during different geological periods (Silver Cliff, CO, USA—Paleogene; El Quevar, Argentina—Miocene; Meissen Volcanic Complex, Germany—Late Carboniferous). All of these megaspherulites have formed exclusively in rhyolitic lava, and their mineral composition is dominated by K-feldspar (sanidine) and SiO2 phases (quartz, cristobalite, tridymite). All megaspherulites represent composite HTCDs, comprising three zones: inner domain (ID), outer domain (OD), and a marginal domain (MD). Early evolution of megaspherulites is characterized by either central cavities and sector- to full-sphere spherulites or dendritic quartz-sanidine domains. The latter consist of bundles of fibrils each radiating from a single point reflecting relatively high growth rates. A common feature of OD and MD of all three megaspherulite occurrences is autocyclic banding. It mainly comprises fibrous (≤ 100 μm length), radially oriented sanidine and quartz, which formed at a temperature close to glass transition temperature (Tg). The termination of megaspherulite growth is marked by centimeter-sized sector-sphere spherulites on the surface. Megaspherulite formation requires limited nucleation, which is probably related to the low phenocryst content of the hosting lava. Latent heat from overlying crystallizing lithoidal rhyolite maintained low undercooling conditions keeping nucleation density low and facilitating high diffusion and growth rates. Late megaspherulite growth and its termination under low diffusion conditions is controlled by cooling close to Tg. Calculations based on literature data suggest that the megaspherulite growth presumably lasted less than 60 years, perhaps 30 to 40 years.
    Keywords: ddc:549 ; Rhyolitic lava ; SEM ; CL ; XRD ; EPMA ; Cristobalite ; Tridymite
    Language: English
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    Polybaric fractional crystallisation of arc magmas: an experimental study simulating trans-crustal magmatic systems (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-06-14
    Description: Crystallisation-driven differentiation is one fundamental mechanism proposed to control the compositional evolution of magmas. In this experimental study, we simulated polybaric fractional crystallisation of mantle-derived arc magmas. Various pressure–temperature trajectories were explored to cover a range of potential magma ascent paths and to investigate the role of decompression on phase equilibria and liquid lines of descent (LLD). Fractional crystallisation was approached in a step-wise manner by repetitively synthesising new starting materials chemically corresponding to liquids formed in previous runs. Experiments were performed at temperatures ranging from 1140 to 870 °C with 30 °C steps, and pressure was varied between 0.8 and 0.2 GPa with 0.2 GPa steps. For most fractionation paths, oxygen fugacity (fO2) was buffered close to the Ni-NiO equilibrium (NNO). An additional fractionation series was conducted at fO2 corresponding to the Re-ReO2 buffer (RRO ≈ NNO+2). High-pressure experiments (0.4–0.8 GPa) were run in piston cylinder apparatus while 0.2 GPa runs were conducted in externally heated pressure vessels. Resulting liquid lines of descent follow calc-alkaline differentiation trends where the onset of pronounced silica enrichment coincides with the saturation of amphibole and/or Fe–Ti–oxide. Both pressure and fO2 exert crucial control on the stability fields of olivine, pyroxene, amphibole, plagioclase, and Fe–Ti–oxide phases and on the differentiation behaviour of arc magmas. Key observations are a shift of the olivine–clinopyroxene cotectic towards more clinopyroxene-rich liquid composition, an expansion of the plagioclase stability field and a decrease of amphibole stability with decreasing pressure. Decompression-dominated ascent trajectories result in liquid lines of descent approaching the metaluminous compositional range observed for typical arc volcanic rocks, while differentiation trends obtained for cooling-dominated trajectories evolve to peraluminous compositions, similar to isobaric liquid lines of descent at elevated pressures. Experiments buffered at RRO provide a closer match with natural calc-alkaline differentiation trends compared to fO2 conditions close to NNO. We conclude that decompression-dominated fractionation at oxidising conditions represents one possible scenario for arc magma differentiation.
    Description: ETH research grant
    Description: Gottfried Wilhelm Leibniz Universität Hannover (1038)
    Keywords: ddc:552.1 ; Arc magmatism ; Magma differentiation ; Fractional crystallisation ; Calc-alkaline rocks ; Polybaric differentiation ; Liquid line of descent
    Language: English
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    Geophysical methods help to assess potential groundwater extraction sites (2021)
    Springer Berlin Heidelberg
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    Publication Date: 2023-06-14
    Description: Complex geology in glacial terrain makes groundwater exploration challenging for water supply companies. Abrupt lateral changes of geological conditions, for example, raise the risk of unsuccessful exploration drilling. At some locations, local water supply companies experience a large number of dry wells, raising the need for better exploration approaches. The use of geophysical techniques enables the detection and characterization of subsurface structures in terms of aquifers and aquitards. We present two examples in which seismic and resistivity methods are combined for subsurface characterization. A thrust structure is detected in the Varde study area in Denmark and a channel structure is mapped in the Hamburg-Sülldorf study area in Germany. The different imaging characteristics of seismic P‑ and S‑waves are demonstrated. The combination of seismic and resistivity methods enables delineating groundwater-bearing and groundwater-barrier layers down to a depth of 150 m.
    Description: Interreg North Sea Region Programme
    Description: Leibniz-Institut für Angewandte Geophysik (3464)
    Keywords: ddc:622.15 ; Seismic reflection ; Electrical resistivity ; P‑waves ; S‑waves ; Geophysics ; Reflexionsseismik ; Widerstandsverfahren ; P‑Wellen ; S‑Wellen ; Geophysik
    Language: English
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    Quantitative 3D imaging of partially saturated granular materials under uniaxial compression (2021)
    Springer Berlin Heidelberg
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    Publication Date: 2023-12-04
    Description: Gauging the mechanical effect of partial saturation in granular materials is experimentally challenging due to the very low suctions resulting from large pores. To this end, a uniaxial (zero radial stress) compression test may be preferable to a triaxial one where confining pressure and membrane effects may erase the contribution of this small suction; however, volume changes are challenging to measure. This work resolves this limitation by using X-ray imaging during in situ uniaxial compression tests on Hamburg Sand and glass beads at three different initial water contents, allowing a suction-dependent dilation to be brought to the light. The acquired tomography volumes also allow the development of air–water and solid–water interfacial areas, water clusters and local strain fields to be measured at the grain scale. These measurements are used to characterise pertinent micro-scale quantities during shearing and to relate them to the measured macroscopic response. The new and well-controlled data acquired during this experimental campaign are hopefully a useful contribution to the modelling efforts—to this end they are shared with the community.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: LabEx Tec 21 (Investissements d’Avenir)
    Description: Technische Universität Hamburg (3140)
    Keywords: Partially saturated granular soils ; Shear strength ; Uniaxial compression tests ; X-ray computed tomography
    Language: English
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    Retrospective evaluation of landslide susceptibility maps and review of validation practice (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-11-24
    Description: Despite the widespread application of landslide susceptibility analyses, there is hardly any information about whether or not the occurrence of recent landslide events was correctly predicted by the relevant susceptibility maps. Hence, the objective of this study is to evaluate four landslide susceptibility maps retrospectively in a landslide-prone area of the Swabian Alb (Germany). The predictive performance of each susceptibility map is evaluated based on a landslide event triggered by heavy rainfalls in the year 2013. The retrospective evaluation revealed significant variations in the predictive accuracy of the analyzed studies. Both completely erroneous as well as very precise predictions were observed. These differences are less attributed to the applied statistical method and more to the quality and comprehensiveness of the used input data. Furthermore, a literature review of 50 peer-reviewed articles showed that most landslide susceptibility analyses achieve very high validation scores. 73% of the analyzed studies achieved an area under curve (AUC) value of at least 80%. These high validation scores, however, do not reflect the high uncertainty in statistical susceptibility analysis. Thus, the quality assessment of landslide susceptibility maps should not only comprise an index-based, quantitative validation, but also an additional qualitative plausibility check considering local geomorphological characteristics and local landslide mechanisms. Finally, the proposed retrospective evaluation approach cannot only help to assess the quality of susceptibility maps and demonstrate the reliability of such statistical methods, but also identify issues that will enable the susceptibility maps to be improved in the future.
    Description: Technische Universität Bergakademie Freiberg (3135)
    Keywords: ddc:551.3 ; Landslides ; Hazard maps ; Predictive performance ; Review ; Swabian Alb
    Language: English
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    Crustal variability along the rifted/sheared East African margin: a review (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-06
    Description: The East African margin between the Somali Basin in the north and the Natal Basin in the south formed as a result of the Jurassic/Cretaceous dispersal of Gondwana. While the initial movements between East and West Gondwana left (oblique) rifted margins behind, the subsequent southward drift of East Gondwana from 157 Ma onwards created a major shear zone, the Davie Fracture Zone (DFZ), along East Africa. To document the structural variability of the DFZ, several deep seismic lines were acquired off northern Mozambique. The profiles clearly indicate the structural changes along the shear zone from an elevated continental block in the south (14°–20°S) to non-elevated basement covered by up to 6-km-thick sediments in the north (9°–13°S). Here, we compile the geological/geophysical knowledge of five profiles along East Africa and interpret them in the context of one of the latest kinematic reconstructions. A pre-rift position of the detached continental sliver of the Davie Ridge between Tanzania/Kenya and southeastern Madagascar fits to this kinematic reconstruction without general changes of the rotation poles.
    Description: Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347
    Keywords: ddc:551.8 ; Davie Ridge ; Davie Fracture Zone ; Gondwana breakup ; Kinematic reconstruction ; Continental fragment
    Language: English
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    Salinity effects on cultured Neogloboquadrina pachyderma (sinistral) from high latitudes: new paleoenvironmental insights (2021)
    Springer Berlin Heidelberg
    Details
    Publication Date: 2023-07-06
    Description: This study presents culture experiments of the cold water species Neogloboquadrina pachyderma (sinistral) and provides new insights into the incorporation of elements in foraminiferal calcite of common and newly established proxies for paleoenvironmental applications (shell Mg/Ca, Sr/Ca and Na/Ca). Specimens were collected from sea ice during the austral winter in the Antarctic Weddell Sea and subsequently cultured at different salinities and a constant temperature. Incorporation of the fluorescent dye calcein showed new chamber formation in the culture at salinities of 30, 31, and 69. Cultured foraminifers at salinities of 46 to 83 only revealed chamber wall thickening, indicated by the fluorescence of the whole shell. Signs of reproduction and the associated gametogenic calcite were not observed in any of the culture experiments. Trace element analyses were performed using an electron microprobe, which revealed increased shell Mg/Ca, Sr/Ca, and Na/Ca values at higher salinities, with Mg/Ca showing the lowest sensitivity to salinity changes. This study enhances the knowledge about unusually high element concentrations in foraminifera shells from high latitudes. Neogloboquadrina pachyderma appears to be able to calcify in the Antarctic sea ice within brine channels, which have low temperatures and exceptionally high salinities due to ongoing sea ice formation.
    Description: Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659
    Description: GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel http://dx.doi.org/10.13039/501100003153
    Keywords: ddc:561 ; foraminifera ; chamber calcification ; salinity effects ; experiments ; paleooceanographic reconstructions
    Language: English
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