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  • Elsevier  (5,804,657)
  • American Geophysical Union (AGU)
  • American Association for the Advancement of Science (AAAS)
  • American Association of Petroleum Geologists (AAPG)
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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
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  • 3
    Publication Date: 2023-11-21
    Description: The world's forests store large amounts of carbon (C), and growing forests can reduce atmospheric CO2 by storing C in their biomass. This has provided the impetus for world-wide tree planting initiatives to offset fossil-fuel emissions. However, forests interact with their environment in complex and multifaceted ways that must be considered for a balanced assessment of the value of planting trees. First, one needs to consider the potential reversibility of C sequestration in trees through either harvesting or tree death from natural factors. If carbon storage is only temporary, future temperatures will actually be higher than without tree plantings, but cumulative warming will be reduced, contributing both positively and negatively to future climate-change impacts. Alternatively, forests could be used for bioenergy or wood products to replace fossil-fuel use which would obviate the need to consider the possible reversibility of any benefits. Forests also affect the Earth's energy balance through either absorbing or reflecting incoming solar radiation. As forests generally absorb more incoming radiation than bare ground or grasslands, this constitutes an important warming effect that substantially reduces the benefit of C storage, especially in snow-covered regions. Forests also affect other local ecosystem services, such as conserving biodiversity, modifying water and nutrient cycles, and preventing erosion that could be either beneficial or harmful depending on specific circumstances. Considering all these factors, tree plantings may be beneficial or detrimental for mitigating climate-change impacts, but the range of possibilities makes generalisations difficult. Their net benefit depends on many factors that differ between specific circumstances. One can, therefore, neither uncritically endorse tree planting everywhere, nor condemn it as counter-productive. Our aim is to provide key information to enable appropriate assessments to be made under specific circumstances. We conclude our discussion by providing a step-by-step guide for assessing the merit of tree plantings under specific circumstances.
    Type: Article , PeerReviewed
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  • 4
    Publication Date: 2023-11-29
    Description: Seaweed farming contributes substantial amounts of organic carbon to the ocean, part of which can be locked for a long term in the ocean and perform the function of ocean carbon sequestration, and the other part can be converted into inorganic carbon through microbial mineralization and aerobic respiration, affecting the pCO2, pHT and dissolved oxygen of seawater. It is generally believed that seaweed farming will cause the seawater to become a sink of CO2 due to carbon fixation by macroalgal photosynthesis. However, little attention has been paid to the fact that seaweed farming environment may sometimes become a source rather than a sink of CO2. Here, through in-situ mesocosm cultivation experiments and eight field investigations covering different kelp growth stages in an intensive farming area in China, we found that compared with the surrounding seawater without kelps, the seawater at the fast-growth stage of kelp was a sink of CO2 (pCO2 decreased by 17−73 μatm), but became a source of CO2 at the aging stage of kelp (pCO2 increased by 20−37 μatm). Concurrently, seawater pHT experienced a transition from increase (by 0.02−0.08) to decline (by 0.03−0.04). In-situ mesocosm cultivation experiments showed that the positive environmental effects (i.e., pCO2 decrease and pHT increase) induced by kelps at the early growth stage could be offset within only 3 days at the late-growth and aging stages. The release of dissolved organic carbon by kelps at the late growth stage increased significantly, supporting the enhancement in microbial abundance and respiration, which was manifested by the remarkable decrease in seawater dissolved oxygen, ultimately leading to CO2 release exceeding photosynthetic CO2 absorption. This study suggests that mature farmed kelps should be harvested in time to best utilize their carbon sink function and environmental benefits, which has guiding significance for the rational management of seaweed farming.
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  • 5
    Publication Date: 2023-12-06
    Description: Highlights: • Inhibitory potential of eelgrass microbiome against aquatic and fecal pathogens • Isolation of epiphytes and endophytes associated with eelgrass leaves and roots • Particularly leaf epibiotic bacteria exhibit significant antimicrobial activity. • Rich secondary metabolite composition by untargeted metabolomics • Potential involvement of eelgrass microbiome in seagrass ecosystem services Seagrass meadows provide crucial ecosystem services for coastal environments and were shown to reduce the abundance of waterborne pathogens linked to infections in humans and marine organisms in their vicinity. Among potential drivers, seagrass phenolics released into seawater have been linked to pathogen suppression, but the potential involvement of the seagrass microbiome has not been investigated. We hypothesized that the microbiome of the eelgrass Zostera marina, especially the leaf epiphytes that are at direct interface between the seagrass host and the surrounding seawater, inhibit waterborne pathogens thereby contributing to their removal. Using a culture-dependent approach, we isolated 88 bacteria and fungi associated with the surfaces and inner tissues of the eelgrass leaves (healthy and decaying) and the roots. We assessed the antibiotic activity of microbial extracts against a large panel of common aquatic, human (fecal) and plant pathogens, and mined the metabolome of the most active extracts. The healthy leaf epibiotic bacteria, particularly Streptomyces sp. strain 131, displayed broad-spectrum antibiotic activity superior to some control drugs. Gram-negative bacteria abundant on healthy leaf surfaces, and few endosphere-associated bacteria and fungi also displayed remarkable activities. UPLC-MS/MS-based untargeted metabolomics analyses showed rich specialized metabolite repertoires with low annotation rates, indicating the presence of many undescribed antimicrobials in the extracts. This study contributes to our understanding on microbial and chemical ecology of seagrasses, implying potential involvement of the seagrass microbiome in suppression of pathogens in seawater. Such effect is beneficial for the health of ocean and human, especially in the context of climate change that is expected to exacerbate all infectious diseases. It may also assist future seagrass conservation and management strategies.
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  • 6
    Publication Date: 2023-12-18
    Description: Total alkalinity (TA) is an important variable of the ocean carbonate system. In coastal oceans, carbonate system dynamics are controlled by a range of processes including photosynthesis and respiration, calcification, mixing of water masses, continental inputs, temperature changes, and seasonal upwelling. Assessments of diel, seasonal and interannual variations in TA are required to understand the carbon cycle in coastal oceans. However, our understanding of these variations remains underdeveloped due to limitations in observational techniques. Autonomous TA measurements are therefore required. In this study, an in situ TA analyzer (ISA-TA) based on a single-point titration with spectrophotometric pH detection was deployed in Tong'an Bay, Xiamen, China, over a five-month period in 2021 to determine diel and seasonal TA variations. The TA observations were combined with an artificial neural network (ANN) model to construct TA prediction models for this area. This provided a simple method to investigate TA variations in this region and was applied to predict surface water TA between March and April 2021. The in situ TA observations showed that TA values in Tong'an Bay varied within a range from 1931 to 2294 μmol kg−1 over the study period, with low TA in late winter, early summer and late summer, and high TA in early winter. The TA variations in late summer and early winter were mainly controlled by mixing of water bodies. The diel variations of TA were greatly determined by tides, with a diel amplitude of 9 to 247 μmol kg−1. The ANN model used temperature, salinity, chlorophyll, and dissolved oxygen to estimate TA, with a root-mean-square error (RMSE) of ∼14 μmol kg−1, with salinity as the input variable with the greatest weight. The approach of combining ISA-TA observations with an ANN model can be extended to study the carbonate system in other coastal regions.
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  • 7
    Publication Date: 2024-01-17
    Description: Highlights • SPM concentration and organic fractions are analyzed in coastal-offshore gradients • Diagnostic model of SPM allows separating fresh, labile from less reactive PON • Analysis of PON fractions reveals a characteristic area, the transition zone • There, particle settling is enhanced, fostering their transport back to the coast, which controls the fate of organic matter • The transition zone is generally confined to water depths below 20 m Abstract Identifying the mechanisms that contribute to the variability of suspended particulate matter concentrations in coastal areas is important but difficult, especially due to the complexity of physical and biogeochemical interactions involved. Our study addresses this complexity and investigates changes in the horizontal spread and composition of particles, focusing on cross-coastal gradients in the southern North Sea and the English Channel. A semi-empirical model is applied on in situ data of SPM and its organic fraction to resolve the relationship between organic and inorganic suspended particles. The derived equations are applied onto remote sensing products of SPM concentration, which provide monthly synoptic maps of particulate organic matter concentrations (here, particulate organic nitrogen) at the surface together with their labile and less reactive fractions. Comparing these fractions of particulate organic matter reveals their characteristic features along the coastal-offshore gradient, with an area of increased settling rate for particles generally observed between 5 and 30 km from the coast. We identify this area as the transition zone between coastal and offshore waters with respect to particle dynamics. Presumably, in that area, the turbulence range and particle composition favor particle settling, while hydrodynamic processes tend to transport particles of the seabed back towards the coast. Bathymetry plays an important role in controlling the range of turbulent dissipation energy values in the water column, and we observe that the transition zone in the southern North Sea is generally confined to water depths below 20 m. Seasonal variations in suspended particle dynamics are linked to biological processes enhancing particle flocculation, which do not affect the location of the transition zone. We identify the criteria that allow a transition zone and discuss the cases where it is not observed in the domain. The impact of these particle dynamics on coastal carbon storage and export is discussed.
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  • 8
    Publication Date: 2024-01-30
    Description: Coastal German waters contain about 1.6 million tons of dumped munition, mostly left after World Wars. This study investigated the benthic macrofauna around the 'Kolberger Heide' munition dumpsite (Baltic Sea). A total of 93 macrofauna grab samples were obtained in the proximity of the munition dumpsite and in reference areas. Environmental variables analysed included the latitude/longitude, depth, terrain ruggedness, sediment grainsize distribution, TNT concentration in the bottom water and distance to the centre of munition dumpsite. The overall abundance, biomass and diversity varied among these groups, though demonstrated no clear differences regarding the proximity to munition and modelled near-bottom dissolved TNT. Among individual taxa, however, a total of 16 species demonstrated significant correlation with TNT concentration. Moreover, TNT may serve as a predictor for the distribution of three species: molluscs Retusa truncatula, Varicorbula gibba and polychaete Spio goniocephala. Possible reasons for the species distribution including their biological traits are discussed.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 9
    Publication Date: 2024-01-30
    Description: Highlights • Global primitive arc lavas (Mg# ≥60) display notable δ49/47Ti heterogeneity. • Residual rutile imposes high δ49/47Ti of 0.24 ± 0.06 ‰ on hydrous, silicic slab melts. • Primitive Aleutian rhyodacites have the same δ49/47Ti as predicted for slab melts. • A variably diluted signature of slab melts is found in all eight subduction zones. • A slab melt component is required to generate silicic primitive arc lavas. Abstract It is still a matter of intense debate to what extent partial melting of the subducting slab contributes to arc magmatism in modern subduction zones. In particular, it is difficult to differentiate between silicate melts formed by partial melting of the slab, and aqueous fluids released during subsolidus dehydration as the main medium for slab-to-mantle wedge mass transfer. Here we use δ49/47Ti (the deviation in 49Ti/47Ti of a sample to the OL-Ti reference material) as a robust geochemical tracer of slab melting. Hydrous partial melting of subducted oceanic crust and the superjacent sedimentary layer produces silicic melts in equilibrium with residual rutile. Modelling shows that such silicic slab melts have notably higher δ49/47Ti (+0.24 ± 0.06 ‰) than their protolith due to the strong preference of rutile for the lighter isotopes of Ti. In contrast, even highly saline fluids cannot carry Ti from the slab and hence hydrous peridotite partial melts have δ49/47Ti similar to mid-ocean ridge basalts (MORB; ca. 0 ‰). Primitive (Mg# ≥60) arc lavas from eight subduction zones that are unaffected by fractional crystallisation of Fe-Ti oxides show a more than tenfold larger variation in δ49/47Ti than found in MORB. In particular, primitive arc lavas display a striking correlation between SiO2 content and δ49/47Ti that ranges from island arc basalts overlapping with MORB, to primitive rhyodacites with δ49/47Ti up to 0.26 ‰ erupted in the western Aleutian arc. The elevated δ49/47Ti of these primitive arc lavas provides conclusive evidence for partial melts of the slab as a key medium for mass transfer in subduction zones. The Aleutian rhyodacites represent a rare example of slab melts that have traversed the mantle wedge with minimal modification. More commonly, slab melts interact with the mantle wedge to form an array of primary arc magmas that are a blend of slab- and peridotite-derived melt. We identify primitive arc lavas with a clearly resolvable slab melt signature in all eight subduction zone localities, confirming that slab melting is prevalent in modern subduction zones.
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  • 10
    Publication Date: 2024-01-30
    Description: Highlights • An event-scale, complete lithostratigraphic column for the Miocene BFVA was created through extensive field volcanology. • Field volcanology was supplemented by volcanic glass geochemistry to separate the eruptions. • An example is presented how to undertake lithostratigraphy-based classification in poorly preserved, deeply eroded volcanic terrains. • In the ancient BFVA landscape, sea cover during eruptions and terrestrial deposition is evident. Abstract This study documents the volcanic evolution of the Miocene silicic Bükk Foreland Volcanic Area (BFVA), Northern Hungary (Central Europe) at an event-scale. The BFVA is a deeply eroded and dissected volcanic field dominated by multiple, several 10-m thick, valley-filling silicic ignimbrite units, which are chemically and texturally very similar to each other. Hence, establishing lateral correlation is a real challenge due to the sporadic and small-scale outcrops and lack of stratotypes. Detailed field observations allowed us to identify eleven lithological members including fourteen eruption events and establish a nearly complete lithostratigraphic correlation between fifteen outcrops across the BFVA. Primary pyroclastic material of each member was sampled, and volcanic glass was geochemically analyzed for major and trace element composition. The geochemical results confirm the field-based classification of the members and enable the correlation of distinct outcrops. The major and trace element composition of the glassy pyroclasts of each member of the BFVA served as basis to create a field-wide chemical reference database for regional correlational studies. Here, a new lithostratigraphic classification scheme (consisting of one lithostratigraphic formation and eleven members) is presented, which reflects the challenges unraveling the stratigraphy of ancient volcanic terrains. The field-based event-scale lithostratigraphy of the BFVA suggests a wet, partly sea-covered depositional environment in the close vicinity of the eruption centers providing favorable conditions to ‘fuel’ silicic explosive phreatomagmatism. On the contrary, paleosol horizons formed after almost each major eruption event or sequence suggests an overall near-coast terrestrial environment for the BFVA, where the emplacement of the pyroclastic material occurred.
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  • 11
    Publication Date: 2024-02-01
    Description: Regime shifts in the diatom–dinoflagellate composition have occurred in the Baltic Sea (BS) and Bohai Sea (BHS) under eutrophication and have affected the entire coastal ecosystem, damaging the regulatory, provisioning, cultural, and supporting service functions of marine ecosystems. Therefore, finding a solution to restore the balance of phytoplankton community composition and mitigate eutrophication is of utmost importance. In this study, the Driver (per capita gross domestic product)-Pressure (terrestrial inputs)-State (seawater environmental parameters)-Impact (proportions of diatoms and dinoflagellates)-Response (eutrophication governance projects) framework served as a guide for our analysis of the causal relationship among various environmental components in the coastal system. The relevant data in BS and BHS spanning from the 1950s to the 2010s were collected and used to construct a diatom–dinoflagellate composition single index, which allowed us to identify the shifts in regimes (mutation points and phases) of the diatom–dinoflagellate composition and environmental factors using sequential t-test analysis. We also identified key environmental factors that moderated the diatom–dinoflagellate composition using redundancy analysis and analyzed the partial effects of the main environmental factors on the diatom–dinoflagellate composition using a generalized additive model. Finally, the regulation of the eutrophication governance investment on diatom–dinoflagellate composition was investigated. We found that (1) BS is a “time machine,” with coastal eutrophication governance and regime shift of diatom–dinoflagellate composition and environmental factors two decades earlier than that in BHS; (2) in BS, the key moderation factor of diatom proportion is SiO3-Si and those of dinoflagellates are sea surface salinity and N:P ratio; in BHS, the key moderation factors of diatom proportion are PO4-P and Si:N ratio and those of dinoflagellate are dissolved inorganic nitrogen and N:P and Si:P ratios; (3) it is projected that BHS will enter its recovery phase from eutrophication after mid-2020s. In summary, the N/P/Si stoichiometric relationships should be given greater consideration, with the exception of the “dose-response” relationship in both sea areas. Our results indicate an urgent need for an improved mechanistic understanding of how phytoplankton biodiversity changes in response to changes in nutrient load and how we should ultimately deal with the challenges that arise.
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  • 12
    Publication Date: 2024-02-05
    Description: A La Niña condition in the equatorial Pacific began in the early summer of 2020 and has lasted more than two and a half years (referred to as the 2020 La Niña hereafter). Predicting its temporal evolution had attracted a lot of attention. Considering the possible phase-locked impact of the 11-year solar cycle on the tropical Pacific variability, in this study the authors present the possible modulations by the solar cycle 25 (SC25) started from December 2019, on the future temporal evolution of the 2020 La Niña. Based on statistical features of historical solar cycles, the authors propose three possible scenarios of the timing of the SC25 maximum year and discuss its possible impacts on the temporal evolution of the 2020 La Niña in the next two years. The ongoing ascending phase of SC25 dampens the development of a super El Niño condition to some extent in 2023.
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  • 13
    Publication Date: 2024-02-12
    Description: Highlights: • Change in sea urchin species composition from RBC and NRBC habitats. • Sand coverage is an important factor that influences the sea urchin species composition. • The relationship between sea urchins and their habitat is species-specific. Sea urchins are important components of marine ecosystems and can act as bioindicators, reflecting the health of reefs. The spatial patterns of sea urchins are largely shaped by the type of habitat. In Hong Kong, coral communities are divided into two distinct types: reef -building coral habitats and non -reef -building coral habitats. In summer 2020, a qualitative survey was conducted using SCUBA at 56 sites across eastern and western waters, recording a total of 11 species from 6 families of sea urchins. Out of these 56 sites, 14 were selected for a quantitative survey to investigate the relationship between sea urchin assemblages and the two types of coral habitat. We found that the species composition of sea urchins differed significantly between the two habitats, and the presence of sand was a critical factor influencing the species composition of sea urchins. Sand coverage had a positive effect on Salmasic sphaeroides abundance but a negative effect on the abundance of Diadema setosum and Heliocidaris crassispina. The distribution of sea urchins across different degrees of sand coverage may be associated with food availability or species -specific adaptive behaviour, likely due to niche preferences.
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  • 14
    Publication Date: 2024-02-12
    Description: Highlights • East Asian climate evolution was dependent on the latitude of the proto-Tibetan Plateau in the deep past; • Global warming induced wetting at mid-latitude East Asian in the mid-Cretaceous; • The proto-Tibetan Plateau uplift led to drying in the subtropical East Asian in the mid-Cretaceous. Abstract Sedimentary records indicate that subtropical and mid-latitude East Asia exhibited considerable drying and wetting, respectively, during the mid-Cretaceous, which is considered to be relevant to much higher atmospheric carbon dioxide (pCO2) concentrations and/or proto-Tibetan Plateau (proto-TP) uplift. In order to explore and compare their roles on the East Asian climate evolution, we conducted simulations of the mid-Cretaceous climate system with different atmospheric pCO2 levels and varying topographies. The results show that both factors had significant influences on the East Asian climate. As the increase in atmospheric pCO2 levels from ∼560–1120 ppmv to ∼1120–2240 ppmv, the precipitation increases considerably over mid-latitude East Asia, but only small changes in the subtropical portion of East Asia occur. Simultaneously, the effects of the proto-TP uplift are opposite to those of global warming trend during that period. Generally, it leads to a precipitation decrease over subtropical East Asia, but rather minor changes over mid-latitude East Asia. These changes are qualitatively consistent with the deduction based on the geological records, but the magnitudes of the modeled precipitation changes are relatively smaller. Therefore, we can conclude that the subtropical East Asian drying during the mid-Cretaceous can be partly explained by the proto-TP uplift, while the mid-latitude East Asian wetting was partly due to global warming. However, additional factor(s) also played a significant role in the East Asian climate evolution during the mid-Cretaceous.
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  • 15
    Publication Date: 2024-02-12
    Description: Carbon dioxide removal (CDR) – the creation, enhancement, and upscaling of carbon sinks – has become a pillar of national and corporate commitments towards Net Zero emissions, as well as pathways towards realizing the Paris Agreement's ambitious temperature targets. In this perspective, we explore CDR as an emerging issue of Earth System Governance (ESG). We draw on the results of a workshop at the 2022 Earth System Governance conference that mapped a range of actors, activities, and issues relevant to carbon removal, and refined them into research questions spanning four intersecting areas: modeling and systems assessment, societal appraisal, policy, and innovation and industry. We filter these questions through the five lenses of the ESG framework and highlight several key ‘cross-cutting’ issues that could form the basis of an integrated ESG research agenda on CDR.
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  • 16
    Publication Date: 2024-02-12
    Description: Highlights • Cu complexation was measured for the first time in the Fram Strait region. • Cu-binding ligand concentrations and binding strength varied longitudinally in the Fram Strait. • More than 99 % of dCu was organically complexed by strong ligands. • On the Greenland shelf the Transpolar Drift and the coastal processes were the main sources of Cu ligands. Abstract The Fram Strait represents the major gateway of Arctic Ocean waters towards the Nordic Seas and North Atlantic Ocean and is a key region to study the impact of climate change on biogeochemical cycles. In the region, information about trace metal speciation, such as copper, is scarce. This manuscript presents the concentrations and conditional stability constants of copper-binding ligands (LCu and log KcondCu2+L) in the water column of Fram Strait and the Greenland shelf (GEOTRACES cruise GN05). Cu-binding ligands were analysed by Competitive Ligand Exchange-Adsorptive Cathodic Stripping Voltammetry (CLE-ACSV) using salicylaldoxime (SA) as competitive ligand. Based on water masses and the hydrodynamic influences, three provinces were considered (coast, shelf, and Fram Strait) and differences were observed between regions and water masses. The strongest variability was observed in surface waters, with increasing LCu concentrations (mean values: Fram Strait = 2.6 ± 1.0 nM; shelf = 5.2 ± 1.3 nM; coast = 6.4 ± 0.8 nM) and decreasing log KcondCu2+L values (mean values: Fram Strait = 15.7 ± 0.3; shelf = 15.2 ± 0.3; coast = 14.8 ± 0.3) towards the west. The surface LCu concentrations obtained above the Greenland shelf indicate a supply from the coastal environment to the Polar Surface Water (PSW) which is an addition to the ligand exported from the central Arctic to Fram Strait. The significant differences (in terms of LCu and log KcondCu2+L) between shelf and coastal samples were explained considering the processes which modify ligand concentrations and binding strengths, such as biological activity in sea-ice, phytoplankton bloom in surface waters, bacterial degradation, and meltwater discharge from 79NG glacier terminus. Overall, the ligand concentration exceeded those of dissolved Cu (dCu) and kept the free copper (Cu2+) concentrations at femtomolar levels (0.13–21.13 fM). This indicates that Cu2+ toxicity limits were not reached and dCu levels were stabilized in surface waters by organic complexes, which favoured its transport to the Nordic Seas and North Atlantic Ocean and the development of microorganism.
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  • 17
    Publication Date: 2024-02-14
    Description: The increasing global demand for seafood, coupled with the limitations of current fish stocks and aquaculture practices, requires the development of sustainable aquaculture solutions. In this context, this study explores the potential of a novel cage technology - Flow2Vortex - for the cultivation of jellyfish, a low-trophic-level organism with increasing market demand. The unique cage design creates a laminar and circular water flow, providing optimal conditions for cultivating fragile planktonic species. Indoor experiments demonstrated the successful growth of jellyfish in the cage, with growth rates of up to 11.6% per day. In addition, field tests in open waters confirmed the cage's ability to maintain a diffuse and controlled flow inside, even under strong external currents. The cage also maintained significantly higher zooplankton concentrations than the surrounding environment, offering a consistent food source for the cultivated jellyfish. These findings highlight the potential of the Flow2Vortex cage for scalable indoor and outdoor cultivation of low-trophic-level organisms, such as jellyfish, contributing to the diversification and sustainability of aquaculture practices.
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  • 18
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  • 20
    Publication Date: 2024-02-22
    Description: Highlights • More diverse non-native taxa generally include more economically costly species. • Chordates, nematodes and pathogens are among significantly over-represented taxa. • Monetary cost magnitude links positively to numbers of costly invasive species. • Costs are biased towards a few ‘hyper-costly’ invasive species groups. • Future invasion rates will continue to harbour new economically costly species. Abstract A dominant syndrome of the Anthropocene is the rapid worldwide spread of invasive species with devastating environmental and socio-economic impacts. However, the dynamics underlying the impacts of biological invasions remain contested. A hypothesis posits that the richness of impactful invasive species increases proportionally with the richness of non-native species more generally. A competing hypothesis suggests that certain species features disproportionately enhance the chances of non-native species becoming impactful, causing invasive species to arise disproportionately relative to the numbers of non-native species. We test whether invasive species with reported monetary costs reflect global numbers of established non-native species among phyla, classes, and families. Our results reveal that numbers of invasive species with economic costs largely reflect non-native species richness among taxa (i.e., in 96 % of families). However, a few costly taxa were over- and under-represented, and their composition differed among environments and regions. Chordates, nematodes, and pathogenic groups tended to be the most over-represented phyla with reported monetary costs, with mammals, insects, fungi, roundworms, and medically-important microorganisms being over-represented classes. Numbers of costly invasive species increased significantly with non-native richness per taxon, while monetary cost magnitudes at the family level were also significantly related to costly invasive species richness. Costs were biased towards a few ‘hyper-costly’ taxa (such as termites, mosquitoes, cats, weevils, rodents, ants, and asters). Ordination analysis revealed significant dissimilarity between non-native and costly invasive taxon assemblages. These results highlight taxonomic groups which harbour disproportionately high numbers of costly invasive species and monetary cost magnitudes. Collectively, our findings support prevention of arrival and containment of spread of non-native species as a whole through effective strategies for mitigation of the rapidly amplifying impacts of invasive species. Yet, the hyper- costly taxa identified here should receive greater focus from managers to reduce impacts of current invasive species.
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  • 21
    Publication Date: 2024-02-23
    Description: Highlights: • Ca. 418 ka Pauzhetka tephra from South Kamchatka was found in 11 marine sediment cores. • New major and trace element analyses allow identification of tephra glasses. • K/Ti and K/Fe maxima mark the Pauzhetka tephra presence in marine sediments. • The tephra occurs at Marine Isotope Stages 12 to 11c and below the Bermuda excursion. • The revised ash dispersal covers vast areas in the NW Pacific and Okhotsk Sea. Abstract: The distal Pauzhetka tephra, formed by a large caldera-forming volcanic eruption in South Kamchatka, has been identified in eleven recently recovered marine sediment cores based on major and trace element compositions of tephra glass. Ten SO264 cores form a transect along the Emperor Seamount Chain (ESC) in the Northwest (NW) Pacific between ∼50.3° and ∼45°N, 800–1200 km southeast of the Pauzhetka caldera. One additional core LV28-41-4 was retrieved in the Okhotsk Sea, ∼600 km west of the caldera. The Pauzhetka tephra glass shards have a characteristic medium-K rhyolite composition and trace element content compatible with the rear-arc position of the source volcano that ensures their identification. In the NW Pacific SO264 cores, the tephra is preserved as layers in cores 33, 47, 49, 53, 55, 56 and 62, as a lens in core 45, and as cryptotephra in cores 57 and 66. It forms a cryptotephra in the Okhotsk Sea core LV28-41-4. Distinctively high XRF-retrieved K/Ti and K/Fe ratios compared to those for the host sediments help identify the Pauzhetka tephra. According to our refined stable oxygen isotope (δ18O)- and magneto-stratigraphy of two studied and two reference cores, the Pauzhetka tephra occurs within a local δ18O maximum during a transition from marine isotope stage 12 to 11c (Termination V) and below a paleointensity minimum referred to as the Bermuda excursion, at ca. 418 ka. Using the tephra age as an isochron, we show that average linear sedimentation rates decrease southward along a transect of the SO264 cores, except in core 55. It partially reflects an intensification of mid-depth currents causing winnowing, erosion or non-deposition along the ESC over the past 418 kyr. An increased linear sedimentation rate in core 55, recovered from the southern leeward side of the Minnetonka Seamount, appears to record the pelagic accumulation protected from the mid-depth current influence. Our findings expand the former ash dispersal area farther southeast in the NW Pacific and southwest in the Okhotsk Sea. The new data on the tephra thickness supports the axis direction of the fallout zone southeast of the Pauzhetka caldera. Our results suggest the Pauzhetka tephra as a key middle Pleistocene isochron for the stratigraphy and correlation of the NW Pacific and Okhotsk Sea sediments.
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  • 22
    Publication Date: 2024-02-23
    Description: Multiple stressors often act concomitantly on ecosystems but detection of species responses follows the “single species-single driver” strategy, and cumulative impacts are seldom considered. During 1990–2010, multiple perturbations in the Caspian Sea, led to the decline of kilka, sturgeon and Caspian seal populations. Specific causes for their collapse were identified but a cumulative assessment has never been carried out. Using loop analysis, a qualitative modelling technique suitable in poor-data contexts, we show how multiple drivers can be combined to assess their cumulative impact. We confirm that the decline of kilka, sturgeon and Caspian seal populations is compatible with a net effect of the concomitant perturbations. Kilkas collapse was certainly due to the outburst of M. leidyi and overfishing. In addition, the excess nutrient might have conspired to reduce these populations. The interplay between concurrent drivers produces trade-offs between opposite effects and ecosystem management must face this challenge
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  • 23
    Publication Date: 2024-02-23
    Description: Highlights • Four rhyolitic explosive eruption events were distinguished from 13.1 Ma to 11.6 Ma. • Silicic volcanism occurred at termination of subduction in a thinning lithosphere. • Rhyolites show extreme magma differentiation and reduced-dry character. • Zircon trace element and Hf isotope fingerprint is an effective correlation tool. Abstract The Tokaj Mts. volcanism occurred in a thinning continental lithosphere regime at the final stage of the subduction process. Using high-precision zircon U-Pb dating, four major explosive eruption events were distinguished. Among them the 13.1 Ma Sátoraljaújhely and the 12.0 Ma Szerencs eruptions could have yielded large amount of volcanic material (possibly 〉 100 km3) and they were associated with caldera collapse as shown by the several hundred-metre-thick pyroclastic deposits and the long (〉100 km) runout pyroclastic flow in case of the 13.1 Ma eruption. The 12.3 Ma Hegyköz and the 11.6 Ma Vizsoly eruptions were relatively smaller. The volcanic products can be readily distinguished by zircon and glass trace elements and trace element ratios, which can be used for fingerprinting and to correlate with distal deposits. The Rb, Ba, Sr content and strong negative Eu-anomaly of the glasses reflect extreme crystal fractionation, particularly for the Szerencs rhyolitic magma. The silicic volcanic products of the Tokaj Mts. show compositional similarities with the so-called ‘dry–reduced–hot’ rhyolite type consistent with an origin in an extensional environment, where the primary magmas were formed by near-adiabatic decompression melting in the mantle with subordinate fluid flux. In contrast, some of the older Bükkalja rhyolitic magmas evolved via more hydrous evolutionary paths, where amphibole played a role in the control of the trace element budget. The significant increase of zircon ε Hf values from −8.8 to + 0.2 in the rhyolitic pyroclastic rocks of Tokaj Mts. with time implies that mantle-derived magmas became more dominant. This can be explained by the specific tectonic setting, i.e. the final stage of subduction when the descending subducted slab became almost vertical, which exerted a pull in the upper lithosphere leading to thinning and accelerated subsidence as well as asthenospheric mantle flow just before the slab detachment.
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  • 24
    Publication Date: 2024-02-27
    Description: Highlights: • The interactions between vortices in a four-vortex flow field using a rotating water tank. • Driven by the strain field, non-ideal vortices stretch along the centerline, and manifest an asymmetric stretching pattern. • Non-ideal vortices disperse vorticity, accumulate filaments, and exhibit distinctive variations in anti-symmetric vorticity distribution, impacting respective merging efficiency. Abstract: Oceanic vortex merging is an important physical process for the vortex evolution and its impact on marine environment. However, limitation of the in-situ oceanic observational data of vortex merging inhabits its better understanding. This study investigates the interactions between non-ideal vortices in a four-vortex flow field in a rotating tank. We examine the merging stages of anticyclonic vortices, influenced by two other cyclonic vortices and their respective dynamical behaviors and quantify the effects of merging on vortex characteristics. The results indicate a strong shear flow between two counter-rotating vortices, which accelerates the motion of the anticyclonic vortex, while cyclonic ones exhibit greater stability. Subsequently, different stages of non-ideal vortex merging in a co-rotating framework are defined, primarily the encircling stage, rapid approaching stage, and merging vortex stage. In addition, we quantify and compare variations in morphological parameters and anti-symmetric vorticity distribution of non-ideal vortices across these stages. The stretching of vortices primarily occurs along the line connecting their centers due to the strain field exerted by neighboring vortices, resulting in an asymmetric stretching pattern in the interactions among non-ideal vortices. Furthermore, during the merging process, non-ideal vortices disperse vorticity outward and accumulate vortex filaments in the surrounding environment, leading to distinctive variations in anti-symmetric vorticity distribution, affecting their respective merging efficiency.
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  • 25
    Publication Date: 2024-02-28
    Description: Highlights • Present day infiltration conditions in an monsoonal environment are studied. • Noble gas concentrations in groundwater are fixed near the soil surface. • Noble gas temperatures represent seasonal infiltration conditions in the monsoon. • Holocene and modern infiltration conditions are quite similar in southern Oman. Abstract Comparing directly measured soil temperatures with noble gas recharge temperatures (NGTs) inferred from noble gas concentrations indicates that the infiltrating soil water equilibrates with soil air near the soil surface during the rainy season. Therefore, NGTs of groundwater recently recharged by the Indian Summer Monsoon (ISM) in the Dhofar Mountains in southern Oman reflect the soil temperatures of the 3-month period and do not represent an annual mean. This finding highlights the need to account for seasonality when interpreting NGT data in regions with pronounced dry and wet seasons. We extend the observations from the southern flank of the Dhofar Mountains to three wells situated on the northern flank of the Dhofar Mountains. Two of these wells yield water of Holocene age that was recharged by the monsoon, their NGT signals are therefore classified as seasonal. The NGT calculated from a third well for recharge conditions during the Last Glacial Maximum (LGM), when the ISM was absent, is approximately 3 °C lower than that of the two Holocene wells. The lower LGM noble gas temperature corresponds well with the lower annual Sea Surface Temperature (SST) in the nearby Arabian Sea. NGTs from published studies from northern Oman are 1–3 °C higher when compared with our data of the same period in the southern Oman. We explain this regional difference of reconstructed temperatures for the LGM and Holocene groundwater with a more continental climatic influence on the infiltration conditions further to the north. The published NGTs from northern Oman show a large temperature difference between the late Holocene and the LGM. In view of our finding of seasonal NGT signals under monsoonal climate, part of this difference may reflect a change in the precipitation regime rather than in air temperature.
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  • 26
    Publication Date: 2024-02-28
    Description: Marine imaging studies have unique constraints on the data collected requiring a tool for defining the biological scope to facilitate data discovery, quality evaluation, sharing and reuse. Defining the ‘target population’ is way of scoping biological sampling or observations by setting the pool of organisms to be observed or sampled. It is used in survey design and planning, to determine statistical inference, and is critical for data interpretation and reuse (both images and derived data). We designed a set of attributes for defining and recording the target population in biological studies using marine photography, incorporating ecological and environmental delineation and marine imaging method constraints. We describe how this definition may be altered and recorded at different phases of a project. The set of attributes records the definition of the target population in a structured metadata format to enhance data FAIRness. It is designed as an extension to the image FAIR Digital Objects metadata standard, and we map terms to other biological data standards where possible. This set of attributes serves a need to update ecological metadata to align with new remotely-sensed data, and can be applied to other remotely-sensed ecological image data.
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  • 27
    Publication Date: 2024-02-29
    Description: Highlights • Negligible Ba removal observed in the Rainbow hydrothermal system. • Insignificant modification of Ba isotope composition of the vent fluid endmember. • Rainbow vent introduces isotopically light Ba (−0.17) to the deep Atlantic Ocean. • Hydrothermal inputs contribute 4.6 ± 2.2 Gmol/yr Ba to the ocean. Abstract The marine barium (Ba) cycle is closely connected to the short-timescale carbon cycle, and Ba serves as a valuable paleo proxy for export production, ocean alkalinity, and terrestrial inputs. However, the marine Ba budget is poorly constrained, particularly regarding the fluxes of hydrothermally sourced Ba, which hinders our understanding of the Ba cycle and use of Ba-based proxies. Recent studies have suggested a modern source-sink imbalance of Ba isotopes in the global ocean, with sources being overall isotopically heavier than the sinks, and the hydrothermal Ba inputs were considered isotopically heavy sources. In this study, we present the first investigation of Ba and its isotopes in a non-buoyant hydrothermal plume based on dissolved and particulate samples collected from the Rainbow hydrothermal vent field on the Mid-Atlantic Ridge. Our data reveal strong hydrothermal signals at near-field stations, as evidenced by helium isotopes, accompanied by elevated concentrations of dissolved and particulate Ba. Dissolved Ba isotope compositions (δ138Ba) in hydrothermally influenced deep waters (∼0.3 ) are lighter than at similar depths of far-field stations (∼0.45 ) in the Atlantic Ocean. The concentrations and isotopic compositions of dissolved and labile particulate Ba in the non-buoyant hydrothermal plume can be explained by conservative mixing between a Ba-enriched hydrothermal component and North Atlantic Deep Water. By extrapolating the correlations to the vent fluid endmember, our results suggest that there is negligible removal of Ba, and insignificant modification of Ba isotopic signatures, from the vent fluid endmember to the non-buoyant hydrothermal plume. This indicates that the Rainbow hydrothermal system introduces isotopically light Ba (−0.17 ± 0.05 ) to the deep Atlantic Ocean. We estimate that global hydrothermal inputs of Ba are 4.6 ± 2.2 Gmol/yr. These observations highlight the potential of hydrothermal Ba to be an isotopically light source component of the marine Ba isotope budget.
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  • 28
    Publication Date: 2024-03-01
    Description: Highlights: • Transcriptomic immune response assessments in seahorse (Hippocampus erectus). • Seahorses exposed in two phases to heat-killed Vibrio and Tenacibaculum strains. • Adaptive immune memory evidence (double-exposed) and increased naivety to Tenacibaculum. • Upregulated gene expression pertaining to potential innate ‘trained immunity’. • Trained immunity potential compensator for deduced MHC II loss of function. Evolutionary adaptations in the Syngnathidae teleost family (seahorses, pipefish and seadragons) culminated in an array of spectacular morphologies, key immune gene losses, and the enigmatic male pregnancy. In seahorses, genome modifications associated with immunoglobulins, complement, and major histocompatibility complex (MHC II) pathway components raise questions concerning their immunological efficiency and the evolution of compensatory measures that may act in their place. In this investigation heat-killed bacteria (Vibrio aestuarianus and Tenacibaculum maritimum) were used in a two-phased experiment to assess the immune response dynamics of Hippocampus erectus. Gill transcriptomes from double and single-exposed individuals were analysed in order to determine the differentially expressed genes contributing to immune system responses towards immune priming. Double-exposed individuals exhibited a greater adaptive immune response when compared with single-exposed individuals, while single-exposed individuals, particularly with V. aestuarianus replicates, associated more with the innate branch of the immune system. T. maritimum double-exposed replicates exhibited the strongest immune reaction, likely due to their immunological naivety towards the bacterium, while there are also potential signs of innate trained immunity. MHC II upregulated expression was identified in selected V. aestuarianus-exposed seahorses, in the absence of other pathway constituents suggesting a possible alternative or non-classical MHC II immune function in seahorses. Gene Ontology (GO) enrichment analysis highlighted prominent angiogenesis activity following secondary exposure, which could be linked to an adaptive immune process in seahorses. This investigation highlights the prominent role of T-cell mediated adaptive immune responses in seahorses when exposed to sequential foreign bacteria exposures. If classical MHC II pathway function has been lost, innate trained immunity in syngnathids could be a potential compensatory mechanism.
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  • 29
    Publication Date: 2024-03-05
    Description: In the past three decades, altimeter-based remote sensing has been a widely used system to estimate ocean surface currents. However, it remains a great challenge to effectively resolve scales below ∼100 km at high latitudes and ∼ 300 km at mid-latitudes. In this study, we propose a scheme that utilizes geostrophic equilibrium and surface quasigeostrophy theory (SQG) to improve surface current resolution by incorporating remote sensing sea surface temperature (SST), sea surface height (SSH), and sea surface salinity (SSS) observations. The scheme separately characterizes the larger-scale flows and smaller-scale motions of surface currents. A case study encompassing the Agulhas surface current demonstrates that the smaller-scale motions associated with temperature fronts are well captured by introducing high spatial-temporal resolution SST data. Furthermore, the reconstructed surface current is systemically evaluated by using surface drogued drifters and a Lagrangian synthetic particle tracking tool throughout the South Indian Ocean (SIO) for 2011–2015. Notably, the reconstructed zonal velocity component is closer to the drifter observations than the meridional counterpart and corresponding velocity phase. Regionally, the Antarctic Circumpolar Current (ACC) showcases superior reconstruction performance, with higher skill scores and lower Lagrangian separation distances. However, a relatively large uncertainty is observed around the Agulhas Retroflection (AR) and Greater Agulhas System (GAS), which are linked to complicated regional dynamic regimes. We finally conduct four simulation experiments to explore the effect of different SST products on surface current reconstruction within the subdomain AR. The results indicate the varying potentials of the four evaluated SST products for informing surface current applications. Specifically, the MWIRSST enhances the likelihood of particles reaching the target field, while DMI OI shortens the average deviation distance of the arrived particles.
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  • 30
    Publication Date: 2024-03-05
    Description: Highlights • Mercury methylation in sediment rapidly transported into water and diatoms. • CH3Hg flux was highest for sediments with higher sulfide and organic content. • Mineral and compressed sediment released minor Hg and CH3Hg. • Higher sediment Hg species flux does not correlate with high sediment content. • Stable isotope incubations provide substantial insight to environmental Hg cycling. Abstract Mercury (Hg) is a conspicuous and persistent global pollutant. Ionic Hg can be methylated into noxious methylmercury (CH3Hg), which biomagnifies in marine tropic webs and poses a health risk to humans and organisms. Sediment Hg methylation rates are variable, and the output flux of created CH3Hg are dependent on sediment characteristics and environmental factors. Thus, uncertainties remain about the formation and flux of CH3Hg from sediment, and how this could contribute to the bioaccumulative burden for coastal organisms in shallow ecosystems. Cores were collected from 3 estuarine locations along the Eastern USA to examine how sediments characteristics influence the introduction of Hg and CH3Hg into the base of the food chain. Stable isotopes of inorganic 200Hg and CH3199Hg were injected into sediments of individual cores, with cultured diatoms constrained to overlying waters. Five different treatments were done on duplicate cores, spiked with: (1) no Hg isotopes (control); (2) inorganic 200Hg; (3) CH3199Hg; (4) both 200Hg and CH3199Hg isotopes, (5) both 200Hg and CH3199Hg into overlying waters (not sediment). Experimental cores were incubated for 3 days under temperature and light controlled conditions. These results demonstrate that upper sediments characteristics lead to high variability in Hg cycling. Notably, sediments which contained abundant and peaty organic material (∼28 %LOI), had the highest pore water DOC (3206 μM) and displayed bands of sulfur reducing bacteria yielded the greatest methylation rate (1.97 % day−1) and subsequent diatom uptake of CH3200Hg (cell quota 0.18 amol/cell) in the overlying water.
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  • 31
    Publication Date: 2024-03-05
    Description: Highlights • Solutions to the climate crisis are not ahistorical. • Both social and technical processes explain their rise (or fall) on the agenda. • Thinking about ocean CDR closely co-evolved with scientific understandings of global climate change. • Ocean CDR methods have followed cycles of hype, controversy and disappointment. • Key sociotechnical configurations and narrative changes explain the new hype around ocean CDR. Abstract While the ocean has long been portrayed as a victim of climate change, threatened by ocean warming and acidification, it is now increasingly framed as a key solution to the climate crisis. In particular, the promising carbon sequestration potential of the ocean is being emphasised. In this paper, we seek to historicise the practices, discourses and actors that have constructed the ocean as a climate change solution space. We conceptualise the debate about the mitigation potential of the ocean as a contested site of governance, where varying actors form alliances and different sociotechnical narratives about climate action play out. Using an innovative quali-quantitative methodology which combines scientometrics with document analysis, observational fieldwork, and interviews, we outline three historical phases in the history of ocean carbon sequestration that follow recurring cycles of hype, controversy and disappointment. We argue that the most recent hype around ocean carbon sequestration was not triggered by a technological breakthrough or a reduction in scientific uncertainty, but by new socio-technical configurations and coalitions. We conclude by showing that how climate change solutions are put on the agenda and become legitimised is both a scientific and political process, linked to how science frames the climate crisis, and ultimately, its governance.
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  • 32
    Publication Date: 2024-03-04
    Description: Climate change is driving compositional shifts in ecological communities directly by affecting species and indirectly through changes in species interactions. For example, competitive hierarchies can be inversed when competitive dominants are more susceptible to climate change. The brown seaweed Fucus vesiculosus is a foundation species in the Baltic Sea, experiencing novel interactions with the invasive red seaweed Gracilaria vermiculophylla, which is known for its high tolerance to environmental stress. We investigated the direct and interactive effects of warming and co-occurrence of the two algal species on their performance, by applying four climate change-relevant temperature scenarios: 1) cooling ) 2 °C below ambient – representing past conditions), 2) ambient summer temperature (18 °C), 3) IPCC RCP2.6 warming scenario (1 °C above ambient), and 4) RCP8.5 warming (3 °C above ambient) for 30 days and two compositional levels (mono and co-cultured algae) in a fully-crossed design. The RCP8.5 warming scenario increased photosynthesis, respiration, and nutrients' uptake rates of mono- and co-cultured G. vermiculophylla while growth was reduced. An increase in photosynthesis and essential nutrients' uptake and, at the same time, a growth reduction might result from increasing stress and energy demand of G. vermiculophylla under warming. In contrast, the growth of mono-cultured F. vesiculosus significantly increased in the highest warming treatment (+3 °C). The cooling treatment (−2 °C) exerted a slight negative effect only on co-cultured F. vesiculosus photosynthesis, compared to the ambient treatment. Interestingly, at ambient and warming (RCP2.6 and RCP8.5 scenarios) treatments, both F. vesiculosus and G. vermiculophylla appear to benefit from the presence of each other. Our results suggest that short exposure of F. vesiculosus to moderate or severe global warming scenarios may not directly affect or even slightly enhance its performance, while G. vermiculophylla net performance (growth) could be directly hampered by warming.
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  • 33
    Publication Date: 2024-03-08
    Description: Marine heatwaves (MHWs) are widely recognized as prolonged periods of significantly elevated sea surface temperatures, leading to substantial adverse impacts on marine ecosystems. However, a comprehensive understanding of their characteristics and potential changes under climate change in the South China Sea (SCS, 0 ∼ 25°N, 105 ∼ 125°E) remains insufficient. Here, utilizing the OISST V2.0 reanalysis dataset, our study first examines MHW characteristics and their trends in the SCS during the historical period (1982 ∼ 2014). Then, in accordance with the criteria established in this study, GFDL-ESM4, EC-Earth3-Veg, NESM3, EC-Earth3, and GFDL-CM4 are identified from the CMIP6 ensemble of 19 models for their enhanced simulations of historical MHW characteristics. Moreover, considering that the fixed and sliding threshold methods offer distinct perspectives on the future evolution of MHWs, we employ both approaches to evaluate MHW characteristics under projected scenarios for the future period (2015 ∼ 2100) and subsequently compare the disparities between the two methodologies. The outcomes obtained using these methods consistently indicate that MHWs in the SCS are anticipated to intensify and persist for longer durations in the future. Besides, addressing seasonal variability, the peak intensity of MHWs falls in May during both the historical period and the four projected future scenarios. This study provides valuable insights into the behavior of MHWs in the SCS within the context of climate change, underscoring the urgency of adopting effective mitigation strategies. Especially, the use of two definition methods provides a more comprehensive set of information for understanding the future changes of MHWs in the SCS.
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  • 34
    Publication Date: 2024-03-14
    Description: Highlights • This study simulates the sedimentation-driven development of multiple stacked BSRs in the Danube paleo-delta, Black Sea. • Formation of multiple BSRs in the Black Sea is controlled by the sequence of sedimentation events of the levees induced by sea-level changes. • Kinetics of phase transitions plays a key role in the coexistence, location, and timing of the multiple BSRs. • Development of multiple stacked BSRs is possible only under a narrow range of parameters, unique for the Danube delta setting. Abstract The gas hydrate stability zone (GHSZ) is defined by pressure-temperature-salinity (pTS) constraints of natural gas hydrate (GH) system. It refers to a depth interval which usually extends several hundred meters into the sediment column at sufficient water depths. The lower boundary of the GHSZ often coincides in seismic reflection data with a bottom simulating reflector (BSR), which indicates the transition between the underlying free gas and the overlying no-free gas zone at the thermodynamic stability boundary. The GHSZ in geological systems is dynamic and can shift in response to sedimentation processes and/or changes in environmental conditions such as bottom water temperatures, hydrostatic pressure, and water salinity. The appearance of multiple BSRs has been interpreted as remnants of former GHSZ shifts which have persisted over geological timescales. In this study, we numerically simulate the sedimentation-driven development of multiple stacked BSRs in the Danube deep-sea fan in the Black Sea. We show that in this dynamic sediment depositional regime sufficient amounts of residual gas remain trapped in the former GHSZ, given sufficiently high initial gas hydrate saturations, so that paleo-BSRs could persist over long time scales ( kyr). In particular, the formation and persistence of multiple BSRs in the Danube Delta is controlled by the sequence of sedimentation events of the levees induced by sea-level change. The kinetics of methane phase transitions between gas hydrate, dissolved methane, and free gas plays a key role in the coexistence, location and timing of the multiple BSRs. Thus, For a given permeability, distinct multiple BSRs appear only for a narrow range of GH formation ( 14 2 12 10 〈 / 10 f k mol m Pa s        ) and dissociation rates ( 16 2 14 10 〈 / 〈 10 d k mol m Pa s       ).
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  • 35
    Publication Date: 2024-03-18
    Description: Highlights: • Huidobria chilensis is an endemic shrub distributed in the south of the Atacama Desert with a disjunct population at the northern coast. • Population and genetic structure correlate with geographic distance and geological factors. • Rain fall and fog, as well as ground water, must be regarded as important factors for populations at the coast and the Andean valleys, respectively. • A combination of different software tool to analyze GBS data allowed a good understanding of the population structure and genetic diversity. Abstract: Survival in hyperarid deserts is a major challenge for life in general and for plants in particular. The Atacama Desert presents harsh conditions such as limited rainfall, crusted soils, high soil salinity, high altitude, and intense solar radiation. These conditions, together with paleoclimatic variations over the last 10 million years, have influenced the genetic structure and connectivity of plant populations, resulting in a diverse flora with high endemism. However, the diversification of most lineages appears to be relatively recent, in contrast to the reported age of the Atacama Desert and the onset and expansion of hyperarid conditions since the late Oligocene and early Miocene. A prominent exception is Huidobria chilensis (Loasaceae), which is thought to be endemic to the Atacama since the Eocene. However, it is still not understood why this plant has been successful in adapting to the harshening environmental conditions. To investigate its genetic structure in relation to the history of the Atacama Desert, we studied 186 individuals from 11 populations using genotyping-by-sequencing (GBS). A total of nearly 56 k genome-wide single nucleotide polymorphisms (SNPs) were analyzed for population structure and genetic diversity. We identified four genetic clusters corresponding to geographic regions: the coastal region south of Tocopilla, the Cordillera de la Costa around Chañaral, and the Copiapó catchment 1 and 2. Genetic diversity within and between these clusters was analyzed along with rainfall, altitude, and landscape data. Although the genetic data support `isolation by distance’ as a major factor for genetic divergence between populations, the study also reveals the influence of topography on the distribution of H. chilensis and highlights the role of hydrologically connected watersheds and rivers in plant migration and colonization. This shapes the species' evolutionary trajectory and genetic diversity. Understanding these patterns in H chilensis lets one draw general conclusions about adaptation and survival strategies of plants in extreme desert environments such as the Atacama.
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  • 36
    Publication Date: 2024-03-15
    Description: Highlights: • Microphytobenthos contributed to the particulate organic matter in both beaches. • Allochthonous materials provide relevant contributions to the POM in surf zones. • Estuarine subsidies' availability determines changes in consumers' isotopic niches. • Higher estuarine trophic subsidies resulted in narrower niches of dominant species. Abstract: Benthic invertebrates in the surf zone of exposed sandy beaches represent important links for energy circulation between benthic and pelagic food webs. This work assesses the trophic ecology of co-occurring epi- and hyper-benthic invertebrates inhabiting the surf zone of sandy beaches located close to an estuarine mouth. It illustrates that different sources of organic matter induce changes in resource utilization. The trophic positions, and the niche width and overlap of species were described using δ13C and δ15N stable isotope analysis. The contribution of different sources to the particulate organic matter was quantified through stable isotopes analysis and fatty acids profiles. Shifts in the trophic niches of dominant species reflected a decrease in the contribution of estuarine carbon to the diets along the coast. This change in contribution of estuarine carbon also influenced trophic niche properties: more diverse resources availability resulted in narrower niches without overlap while less diverse resources resulted in broad isotopic niches and a highest overlap. Results show that spatial variations in the availability of resources can modify carbon pathways and trophic interactions in coastal food webs. Whenever resources are abundant, species display a more specialized diet while food scarcity leads to broader diets, a pattern consistent with the optimal foraging theory. This resource maximization behavior commonly observed in nature is also occurring in surf zone ecosystems.
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  • 37
    Publication Date: 2024-03-22
    Description: High dissolved iron (dFe) concentrations of the order of 10-100 nmol L-1 are a feature of waters influenced by sedimentary inputs in oxygen minimum zones (OMZ). However, the temporal development of dFe concentrations is poorly defined due to a general reliance on snapshot cross-shelf sections to study marine trace metal dynamics. Multiple cruise campaigns since the 1980s have investigated Fe dynamics over the Peruvian shelf, particularly between 9-17°S where the shelf is broad, extremely productive and known to feature benthic dFe effluxes which are amongst the highest measured globally. This extensive long-term dataset uniquely allows us to study the interannual variability in dFe concentrations and their response to El Niño–Southern Oscillation (ENSO) events. By combining data from 11 cruises during the period 1984-2017 we are able to evaluate dFe dynamics on interannual timescales in a major OMZ. The region where average dFe concentrations are sensitive to variations in ENSO is confined to a subsurface layer at depths between 50-150 m, particularly in the narrow coastal region within 50 km of the coastline. Subsurface dFe concentrations were generally low during El Niño events (0.7-15.4 nmol L-1) and relatively high with a wider range of variability during the cold ENSO phase (1.1-52.1 nmol L-1). Inverse relationships between wind speed and surface/subsurface dFe were evident. In the subsurface layer, this may be attributable to enhanced dFe offshore transport along isopycnals when upwelling-favorable winds relax in accordance with previously outlined theories. Surface layer (〈40 m) dFe variability was likely associated with a dilution and/or oxidation effect depending on the strength of wind driven water column mixing. Upwelling brings macronutrient-rich water into the euphotic zone, but its intensity had a limited impact on upper layer dFe concentrations possibly due to the influence of an onshore geostrophic flow. Interannual variability in surface chlorophyll-a (Chl-a) was found to correlate with dFe concentration in the offshore zone of northern Peru. This is consistent with bioassay experiments and climatological residual nitrate concentrations which both indicate proximal Fe limitation of phytoplankton growth over and beyond the northern Peruvian shelf. Overall, our work highlights the importance of physical factors driving short-term variations in Fe availability in one of the world’s most economically important fishery regions and suggests that, despite pronounced spatial and temporal variability in dFe concentrations, the ENSO phase has an impact on dFe availability.
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  • 38
    Publication Date: 2024-03-22
    Description: Underwater image restoration has been a challenging problem for decades since the advent of underwater photography. Most solutions focus on shallow water scenarios, where the scene is uniformly illuminated by the sunlight. However, the vast majority of uncharted underwater terrain is located beyond 200 meters depth where natural light is scarce and artificial illumination is needed. In such cases, light sources co-moving with the camera, dynamically change the scene appearance, which make shallow water restoration methods inadequate. In particular for multi-light source systems (composed of dozens of LEDs nowadays), calibrating each light is time-consuming, error-prone and tedious, and we observe that only the integrated illumination within the viewing volume of the camera is critical, rather than the individual light sources. The key idea of this paper is therefore to exploit the appearance changes of objects or the seafloor, when traversing the viewing frustum of the camera. Through new constraints assuming Lambertian surfaces, corresponding image pixels constrain the light field in front of the camera, and for each voxel a signal factor and a backscatter value are stored in a volumetric grid that can be used for very efficient image restoration of camera-light platforms, which facilitates consistently texturing large 3D models and maps that would otherwise be dominated by lighting and medium artifacts. To validate the effectiveness of our approach, we conducted extensive experiments on simulated and real-world datasets. The results of these experiments demonstrate the robustness of our approach in restoring the true albedo of objects, while mitigating the influence of lighting and medium effects. Furthermore, we demonstrate our approach can be readily extended to other scenarios, including in-air imaging with artificial illumination or other similar cases.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 39
    Publication Date: 2024-03-25
    Description: The impact of oxygen on the preservation of organic matter in marine surface sediments is still controversial. We revisited this long-standing debate by determining the burial efficiency of sedimentary organic matter in the Black Sea, the largest anoxic and euxinic basin in the modern ocean. Surface sediments were sampled in the Danube paleodelta on the northwestern margin of the Black Sea at 420–1550 m water depth. Steady-state modeling of solid species (particulate organic carbon and nitrogen) and solutes (ammonium, sulfate, and total alkalinity) in sediments was performed to quantify rates of mass accumulation, particulate organic matter (POM) degradation, and POM burial. We develop a novel analytical model to quantify these rates applying an inverse modelling approach to down core data accounting for molecular diffusion, sediment burial and compaction. Our model results indicate that 56.7 ± 6.6 % of the particulate organic matter deposited in the study area is not degraded in surface sediments but accumulates below 10 cm sediment depth. This burial efficiency is substantially higher than those previously derived for seafloor areas underlying oxygenated bottom waters. Hence, our study confirms previous studies showing that euxinic bottom water conditions promote the preservation of particulate organic matter in marine sediments.
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  • 40
    Publication Date: 2024-03-25
    Description: The TetraEther indeX of 86 carbon atoms (TEX86) is widely used as a proxy to reconstruct past sea surface temperatures. Most current applications of TEX86 are primarily based on analyzing the composition of isoprenoid glycerol dialkyl glycerol tetraethers (isoGDGTs) that comprise TEX86 in sediments, with the assumption that the sedimentary isoGDGTs are mainly derived from the surface mixed layer. Here we report on the variations in the isoGDGT distribution, archaeal abundance and community through the water column of the Western Pacific Ocean, directly testing the export depth of isoGDGTs and constraining the temperature records of TEX86. Our data show that maximum isoGDGT concentrations occurred in subsurface waters (150–200 m) with maximum archaeal abundances. The ratio between isoGDGTs bearing 2 vs. 3 cyclopentane moieties, i.e. [2/3] ratio, increased with depth, which is likely related to the shift of the archaeal community from Ca. Nitrosopelagicus-dominance to norank_f__Nitrosopumilaceae-dominance. Models based on the [2/3] ratios in the water column predicted an average export depth of isoGDGTs to sediments of around 150–200 m, consistent with the robust relationship between the compiled sedimentary TEX86 and the annual mean subsurface temperature. Taken together, our findings support that TEX86 records subsurface rather than surface temperatures in the open ocean.
    Type: Article , PeerReviewed
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  • 41
    Publication Date: 2024-03-25
    Description: Cadmium (Cd) has a nutrient-like distribution in the ocean, similar to the macronutrient phosphate. Significant isotope fractionation induced by the biological cycling of Cd makes it a potential tracer for nutrients and productivity. However, the Cd flux and Cd isotope composition of marine sediments can also be influenced by local redox conditions and partial remineralization of organically hosted Cd. These confounding factors are under-constrained and render it challenging to use Cd as a reliable paleoproxy. To understand the relative importance of each of these processes, we examined the Cd isotope systematics of 69 modern sediments deposited across a wide range of environments. We complement these data with four profiles of particulate Cd isotope compositions from the Southern Ocean. We report three main results. First, we show that the sedimentary flux of Cd is tightly coupled to that of organic matter. Second, most Cd burial occurs in regions with some bottom-water oxygen, and the flux of CdS to anoxic regions is, globally, minor. Finally, we find that remineralization can substantially modify sedimentary Cd isotope compositions, though it is challenging to relate pelagic and sedimentary processes. For example, we find that the relationship between sedimentary Cd isotope compositions and surface seawater [Cd] is the reverse of that predicted by isotope reactor models. Likewise, sedimentary Cd isotope compositions are anti-correlated with bottom-water oxygen. While this pattern is consistent with preferential remineralization of isotopically heavy Cd, profiles of marine particulate matter reveal the reverse, whereby the Cd isotope composition of large particles, which are most likely to reach the seafloor, becomes increasingly ‘heavy’ with depth. These results highlight how productivity, redox, and remineralization all influence the flux and isotope composition of Cd to marine sediments. While our study suggests that there is no simple way to relate sedimentary Cd isotopes to surface nutrient utilization, our data point toward several potential controls that could form the basis of novel proxies for local redox conditions and remineralization.
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  • 42
    Publication Date: 2024-03-25
    Description: Highlights • Developed an innovative weighted outlier detection function that adaptively selects the best outlier detection technique, markedly improving precision and robustness in multibeam echosounder data analysis. • Demonstrated superior performance of the weighted function over traditional methods, achieving higher precision, recall, and F1 scores, pivotal for accurate seafloor mapping. • Enhanced data quality for geoscientific applications by effectively identifying and removing outliers without introducing data voids, preserving the integrity of multibeam sonar data. • The function’s significance extends to supporting sustainable environmental and resource management practices through improved accuracy in seabed mapping. • Discussed the adaptability of the method to various outlier patterns and its limitations, highlighting the need for further research and validation across different marine environments and data types. Abstract Multibeam sonar data are a valuable tool for seafloor mapping and geological studies. However, the presence of outliers in multibeam data can distort the results of analyses and reduce the accuracy of seafloor maps. In this paper, we define a weighting function based on the performance of various outlier detection techniques (OTDs) for detecting outliers in multibeam data, which calculates an outlier probability score for each sounding. Our results show that each OTD has its own strengths and weaknesses, and that a combination of outlier detection techniques is promising to improve reproducibility, explainability and the accuracy of the detection process. To address the challenge of detecting outliers in multibeam data, we propose a weighted outlier detection function that outperforms individual outlier detection techniques in terms of precision, recall and F1 scores by considering their strengths and combining them in a way that accounts for variations in the data. The function detects various types of outliers with high precision and recall values, resulting in valuable improvements in outlier detection performance for multibeam data. Overall, our proposed workflow has the potential to significantly improve the way multibeam data cleaning is performed, with the weighted outlier detection function being applied first, detecting most of the outlier automatically, followed by a domain-expert review of a small group of soundings whose automatic outlier labelling is not unequivocal.
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  • 43
  • 44
    Publication Date: 2024-03-25
    Description: The ocean region along the latitude of 40oS in the South Atlantic, characterized by enhanced primary productivity, forms a transition zone between the nutrient replete but iron depleted Southern Ocean, and the nitrate and iron depleted Subtropical Gyre. Here, we present distributions of nutrient-type dissolved and particulate trace metals (dTMs and pTMs) including cadmium (Cd), nickel (Ni), copper (Cu), and zinc (Zn) in the South Atlantic from the GEOTRACES GA10 cruises. Phytoplankton uptake, riverine and atmospheric inputs shaped dTM and pTM concentrations in surface waters (dCd 27.8±36.0 pmol kg-1, n=222; dCu 0.732±0.429 nmol kg-1, n=222; dNi 3.38±0.52 nmol kg-1, n=219; dZn 0.332±0.398 nmol kg-1, n=214). Subsurface nutrients and dTMs (dCd 563±184 pmol kg-1, n=335; dCu 1.819±0.773 nmol kg-1, n=334; dNi 6.19±1.06 nmol kg-1, n=330; dZn 3.71±2.10 nmol kg-1, n=333) were controlled by the mixing of Antarctic origin waters and North Atlantic Deep Waters (NADW) with negligible contributions from local remineralization. Dissolved and particulate TMs in the Argentine Basin showed elevated concentrations towards the seafloor because of benthic inputs. Direct hydrothermal inputs of dTMs and pTMs to deep waters were not observed along the transect. The Cd-Cu-Zn-phosphate stoichiometries of Antarctic origin waters were set by a combination of dynamic physical circulation and preferential uptake of Cd, Cu, and Zn relative to phosphate in surface waters because of a dominance by diatoms in the Southern Ocean. Water mass mixing subsequently produced convoluted dCu-P and dZn-P relationships and apparent linear dCd-P and dNi-P relationships in the South Atlantic. More importantly, endmember characteristics of Antarctic waters and NADW are largely fixed in their formation regions in high latitude oceans. Therefore, the highly dynamic high latitude oceans are key regions that supply nutrients and TMs at specific ratios to low latitude oceans via the thermohaline circulation. Changes to processes in the high latitude oceans may have consequences for marine primary productivity downstream, and hence the global carbon cycle.
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  • 45
    Publication Date: 2024-03-25
    Description: Highlights • Investigation into the potential of Porites microatolls for SST reconstruction. • Comparison between recent and more conventional coral paleoclimatology methods. • Application of Srsingle bondU and Li/Mg paleothermometer. • Accuracy and reproducibility of Sr/Ca proved to be the most suitable proxy for SST reconstruction. Abstract Massive dome-shaped coral Porites are the predominant choice for paleoclimate studies due to their consistent and reliable growth. When growing close to sea level, they become limited in their vertical growth and form so-called ‘microatolls’. Microatolls have not yet been extensively explored for paleoclimate reconstruction. Here, we investigate how reliable modern Porites microatolls are against empirical sea-surface temperature using Sr/Ca, δ18O, Li/Mg and Srsingle bondU paleothermometry methods on samples from the Society Islands, French Polynesia. Our results show Sr/Ca ratios have the lowest Standard Error of the Inverse Prediction (SEIP) at 0.415 °C (N = 41) with a calibration of Sr/Ca (mmol mol−1) = −0.082 ± 0.006 SST (°C) + 11.256 ± 0.170 and with high reproducibility across multiple corals. The reproducibility of δ18O was less good, with SEIP increasing to 0.829 °C (N = 41). Considering methods directly from the literature, Li/Mg ratio empirically corrected for Sr/Ca had the best balance between bias and precision where no local calibration could be available. This study independently evaluates and confirms the suitability of Porites microatolls from well-flushed environments for paleoclimate studies. Fossil dome-shaped Porites grow anywhere between near-surface and roughly 20 m depths which inherently incorporates uncertainty into any sea surface temperature reconstruction. This uncertainty is significantly reduced for microatolls due to their well-constrained bathymetry. The study represents a fundamental step in paleoclimate research targeting consistently near the water-air interface bringing reliability and, especially when combined with their ability to reconstruct past sea-level changes, microatolls have the potential to be central for future paleoenvironmental studies.
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  • 46
    Publication Date: 2024-03-26
    Description: This review has been undertaken to understand the effectiveness of ocean acidification on oceanic micronutrient metal cycles (iron, copper and zinc) and its potential impacts on marine biota. Ocean acidification will slow down the oxidation of Fe(II) thereby retarding Fe(III) formation and subsequent hydrolysis/precipitation leading to an increase in iron bioavailability. Further, the increased primary production sustains enzymatic bacteria assisted Fe(III) reduction and subsequently the binding of weaker ligands favours the dissociation of free Fe(II) ions, thus increasing the bioavailability. The increasing pCO2 condition increases the bioavailability of copper ions by decreasing the availability of free CO32− ligand concentration. The strong complexation by dissolved organic matter may decrease the bioavailable iron and zinc ion concentration. Since ocean acidification affects the bioavailability of essential metals, studies on the uptake rates of these elements by phytoplankton should be carried out to reveal the future scenario and its effect on natural environment.
    Type: Article , PeerReviewed
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  • 47
    Publication Date: 2024-01-08
    Description: Several empirical formulations used over time to estimate the fundamental ionospheric parameter hmF2 have been compared in this study. These are the first formulation proposed by Shimazaki (1955) (SHI-1955) as a function of the propagation parameter M(3000)F2, the more accurate BSE-1979 formula proposed by Bilitza et al. (1979) and firstly adopted by the International Reference Ionosphere (IRI) model, and the newest Altadill-Magdaleno-Torta-Blanch (AMTB-2013) (Altadill et al., 2013) and SHU-2015 (Shubin, 2015) models, obtained with a different approach with no explicit dependence on any ionospheric parameter and added as alternative options in the IRI-2016. The evaluation of the accuracy of the available formulation is performed by comparing the modeled values of hmF2 with those simultaneously obtained with independent measurements from the Incoherent Scatter Radar (ISR) installed at the Millstone Hill ionospheric station. The database considered consists of 3626 measurements, thus allowing the evaluation of the results for different heliogeophysical conditions. SHI-1955 and BSE-1979 formulations are evaluated also using input data manually scaled from ionograms recorded at the same location, with the aim of evaluating their accuracy when updated with validated data rather than modeled ones. The SHU-2015 is confirmed the best option in any condition, while AMTB-2013 turns out to perform poorly during night, when SHI-1955 and BSE-1979 fed by validated data can be used for trend analyses due to the high correlation with ISR data. Despite this, BSE-1979 performs better with modeled parameters as input, in terms of RMSE and mean deviation from ISR data. The use of SHI-1955 with CCIR-modeled M(3000)F2 is discouraged under daytime conditions even for long trend analyses.
    Description: Published
    Description: 3202-3211
    Description: OSA3: Climatologia e meteorologia spaziale
    Description: JCR Journal
    Keywords: hmF2 ; IRI-2020 ; ISR ; Ionosonde ; 01.02. Ionosphere ; 05.07. Space and Planetary sciences
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 48
    Publication Date: 2024-01-08
    Description: Experimental data are publicly available here: https://data.mendeley.com/datasets/f78bmhr628/1
    Description: Temperature is a major source of inaccuracy in high-sensitivity accelerometers and gravimeters. Active thermal control systems require power and may not be ideal in some contexts such as airborne or spaceborne applications. We propose a solution that relies on multiple thermometers placed within the accelerometer to measure temperature and thermal gradient variations. Machine Learning algorithms are used to relate the temperatures to their effect on the accelerometer readings. However, obtaining labeled data for training these algorithms can be difficult. Therefore, we also developed a training platform capable of replicating temperature variations in a laboratory setting. Our experiments revealed that thermal gradients had a significant effect on accelerometer readings, emphasizing the importance of multiple thermometers. The proposed method was experimentally tested and revealed a great potential to be extended to other sources of inaccuracy, such as rotations, as well as to other types of measuring systems, such as magnetometers or gyroscopes.
    Description: This work was funded by “Regione Lazio” (Italy) with European Regional Development Fund (Italy, Lazio) through the call “Gruppi di Ricerca 2020 (POR FESR LAZIO 2014 – 2020), project number: A0375-2020-36674
    Description: Published
    Description: 114090
    Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio
    Description: JCR Journal
    Keywords: gravimeter ; gravimetry ; 05.04. Instrumentation and techniques of general interest ; 04.02. Exploration geophysics
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  • 49
    Publication Date: 2024-01-08
    Description: This study is focused on fluids characterization and circulations through the crust of the Irpinia region, an active seismic zone in Southern Italy, that has experienced several high-magnitude earthquakes, including a catastrophic one in 1980 (M = 6.9 Ms). Using isotopic geochemistry and the carbon‑helium system in free and dissolved volatiles in water, this study aims to explore the processes at depth that can alter pristine chemistry of these natural fluids. Gas-rock-water interactions and their impact on CO2 emissions and isotopic composition are evaluated using a multidisciplinary model that integrates geochemistry and regional geological data. By analyzing the He isotopic signature in the natural fluids, the release of mantle-derived He on a regional scale in Southern Italy is verified, along with significant emissions of deep-sourced CO2. The proposed model, supported by geological and geophysical constraints, is based on the interactions between gas, rock, and water within the crust and the degassing of deep-sourced CO2. Furthermore, this study reveals that the Total Dissolved Inorganic Carbon (TDIC) in cold waters results from mixing between a shallow and a deeper carbon endmember that is equilibrated with carbonate lithology. In addition, the geochemical signature of TDIC in thermal carbon-rich water is explained by supplementary secondary processes, including equilibrium fractionation between solid, gas, and aqueous phases, as well as sinks such as mineral precipitation and CO2 degassing. These findings have important implications for developing effective monitoring strategies for crustal fluids in different geological contexts and highlight the critical need to understand gas-water-rock interaction processes that control fluid chemistry at depths that can affect the assessment of the CO2 flux in atmosphere. Finally, this study highlights that the emissions of natural CO2 from the seismically active Irpinia area are up to 4.08·10+9 mol·y-1, which amounts is in the range of worldwide volcanic systems.
    Description: Published
    Description: 165367
    Description: OST3 Vicino alla faglia
    Description: OST5 Verso un nuovo Monitoraggio
    Description: JCR Journal
    Keywords: CO(2) output; Carbon isotopes; Degassing; Earthquakes; Noble gases; Precipitation ; 04.04 Solid Earth ; 01.01. Atmosphere ; 03.01. General ; 03.02. Hydrology ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 50
    Publication Date: 2024-01-08
    Description: A new method to define a background for the ionospheric electron density (Ne) is proposed, making use of mid-latitude measurements under different solar conditions from the Langmuir Probes onboard CHAMP and three identical Swarm satellites. In particular, CHAMP measurements during the years 2004 and 2009, and Swarm observations during 2016 and 2017 have been considered in the 15°-wide latitudinal belt from 35°N to 50°N, and from 0° to 360° in longitude. CHAMP/Swarm in-situ Ne measurements have been then used to check and compare this new defined background with the one computed directly from IRI-2016 Ne output at satellite altitude. The distributions of the relative deviations between the two backgrounds, and of positive and negative anomalies (i.e., Ne variations from each background greater than 30%) with respect to the geomagnetic activity levels have been evaluated under each investigated condition, namely year/satellite, season, night-time or noon hours. Results of this comparison highlight a general overestimation of Ne from IRI during noon hours, while a better agreement between the two backgrounds is found during night-time. However, an underestimation of IRI with respect to Swarm-derived background is found for 2017 data. Finally, the analysis of 2004 plasma data suggests that the IRI-2016 model can be used as a background during periods characterized by high levels of geomagnetic activity. Due to the difficulties to construct a background for satellite data, the proposed method can be considered an useful tool for analyses of electron density variations at the heights of the satellites in Low Earth Orbits (LEO).
    Description: Published
    Description: 1183-1195
    Description: OSA3: Climatologia e meteorologia spaziale
    Description: JCR Journal
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  • 51
    Publication Date: 2024-01-08
    Description: The Campo Felice basin, in the central Apennines seismic belt (Italy), developed in the hangingwall of a 30 km-long system of NW-trending normal faults with Holocene paleoseismic activity and potential sources of M 6–7 earthquakes. We provide the first subsurface images of a key portion of the basin bounded by the Mt. Cefalone fault along two intersecting profiles trending NNE-SSW (CF-Dip, 1195 m-long) and WNW-ESE (CF-Strike, 1315-m long). We combined high-resolution depth-migrated reflection sections with P-wave velocity and electrical resistivity tomography models. CF-Dip profile displays a wedge-like syn-tectonic sedimentary sequence of alluvial and glacial deposits with Vp ∼ 2500–3000 m/s and resistivity 〉 500 Ωm in the hangingwall of Mt. Cefalone fault, overlying a high-Vp (〉4000 m/s) limestone bedrock ∼ 300 m deep. The whole sequence displays reflectors truncated by the Mt. Cefalone fault zone and subsidiary antithetic faults. CF-Strike profile, tied to three 80–110 m-deep boreholes, shows a thick fluvio-lacustrine sequence with low-Vp (〈2000 m/s) and low resistivity (〈100 Ωm), and a bedrock that deepens to the southeast (〉450 m). Single-station ambient noise measurements display Horizontal to Vertical Spectral Ratios with peaks at ∼1 Hz, decreasing to ∼0.8 Hz to the southeast in agreement with the bedrock deepening indicated by seismic profiling. According to our results, the Campo Felice basin is a deep asymmetric half-graben controlled by faulting whose activity likely started before the Middle Pleistocene. Our minimum displacement estimate accrued in the past 0.5 Ma by the Mt. Cefalone fault is in the range of ∼100–250 m.
    Description: Published
    Description: 230170
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: OST3 Vicino alla faglia
    Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio
    Description: JCR Journal
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  • 52
    Publication Date: 2024-01-09
    Description: A common practice of seismology is to analyze earthquake occurrence in terms of events catalogues, with the aim to either find useful correlations between internal mechanisms under study and their outcome in the spatial/temporal series of the events or, more directly, to assess some statistical rules from observations. With this approach, catalogues are often searched for some recognizable patterns or behaviors: in this work we present a software tool created to reveal a particular kind of events sequences. The idea follows from the concept of multiplets, a well known events pattern often found in seismic series. A multiplet is defined as a sequence of events, all near in space and time and exhibiting similar magnitudes. The amount of multiplets in seismic series is related, as it is for other clustering mechanisms, to underlying correlations in the physics of the events. The software, built from scratch, scans seismic catalogues in search of events clustered as “multiplets”: this is done through the thorough application of comparison tests whose parameters thresholds are both user defined and semi-automated. The tool is however more “general” in the sense that by varying values of the filtering parameters it can reveal other kind of patterns too. While we think that this tool can be thought as a general purpose space–time series analyzer, we have found it particularly useful when applied to the results of a seismic simulator with the purpose of assessing their adherence with the observed seismicity. It can be used as a sort of metric to quantify the simulation predictions effectiveness in terms of presence of similar multiplets distributions in simulated vs. real catalogues. The software has been entirely developed in the Wolfram Language (Mathematica), a commercial powerful environment for scientific calculus and results report, but the main computational routine has been also ported to python for open-source, copyleft usage.
    Description: Published
    Description: 105496
    Description: OST5 Verso un nuovo Monitoraggio
    Description: JCR Journal
    Keywords: seismic multiple events ; 05.01. Computational geophysics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 53
    Publication Date: 2024-01-09
    Description: We present the first high-resolution ultrashallow seismic image of a normal fault segment that ruptured the surface during the Mw 6.5 2016 Norcia earthquake (central Italy). This is the only fault, in the entire activated 25 km-long system, cutting a thick succession of Quaternary deposits, with an associated 3-m-high cumulative scarp. A 190-m-long profile crossing the fault was acquired and analyzed combining reflection seismic, non-linear multiscale refraction P-wave tomography and multi-channel analysis of surface waves. The joint interpretation of the seismic reflection, P- and S-wave velocity images unravels a 100-m-thick sequence of sandy-gravel alluvial fans, disrupted by a main normal fault zone, named as Valle delle Fonti fault (Vf1), which branches upward into three splays. The eastern splay of Vf1 matches with the 2016 coseismic surface rupture. Near-surface truncated reflections and growth strata in the hanging wall of the western and intermediate splays attest to their activity in Late Pleistocene-Holocene times. We also detect an additional normal fault in the footwall of Vf1, probably inactive since the Late Pleistocene. Comparing the seismic images with the Poisson's coefficient model and with the results of a previous electrical resistivity tomography, we constrain the lithology and the hydraulic behavior of the uppermost 50 m of the fault. A steep, W-dipping zone with high-Vp, very high Poisson's coefficient and low resistivity correlates with the eastern splay of Valle delle Fonti fault and unravels a water-saturated region. These results suggest that the fault zone may act as a partial barrier for horizontal fluid flow. Our findings indicate that the active fault zone detected by seismic imaging is much wider than what previously estimated from surface geological analyses. In terms of surface faulting hazard, this study confirms the effectiveness of high-resolution seismic surveys in defining the geometry and physical properties of active fault zones.
    Description: Published
    Description: 229733
    Description: OST3 Vicino alla faglia
    Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio
    Description: JCR Journal
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  • 54
    Publication Date: 2024-01-09
    Description: In this paper we present the new high-resolution magnetic anomaly map of the La Fossa Caldera system and Lipari island (Southern Italy), obtained by merging two low-altitude aeromagnetic surveys. In these islands a variegated ensemble of magnetic anomalies develops in the north-south direction. The La Fossa Caldera is characterized by very high-intensity and short-wavelength magnetic anomalies, related to mafic intrusive/effusive sources, mainly aligned along the NNW-SSE and NS faults. Instead, the Lipari island is characterized by lower intensity anomalies related to sources with more evolved chemistry, elongated in the NE-SW, NNE-SSW and EW of the subordinate faults. Both the two sets of structures belong to the Tindari-Letojanni strike slip fault-system, a regional lineament along which the southern side of the Aeolian Archipelago is emplaced. The study identifies three distinctive magnetic zones on the Lipari island: the southern, the central, and the north-western ones. The southern zone is characterized by negative magnetic monopoles in correspondence with the younger rhyolitic domes and a Curie Isotherm upwelling. The central part of the island has an average lower intensity of positive anomalies, corresponding to the less evolved products of the intermediate Lipari volcanic epochs. The north-western side is characterized by higher intensity anomalies related to older volcanic epochs. The interplay among strike-slip tectonics, chemistry of the uprising magmas, and the thermal setting has contributed to the overall anomaly pattern in this sector of the Aeolian Archipelago. This interpretation is supported by the application of digital enhancement to the total intensity magnetic anomaly field and by the spatial correlation analysis of the magnetic and volcano-tectonic features. The obtained insights are useful to better understand the relationship between arc volcanism and tectonics. Moreover, they can also outline new inferences to forecast future eruptions of the active La Fossa volcanic system. In fact, recent unrest signals were registered at La Fossa Cone, which is one of the present-day active volcanoes of the Aeolian Archipelago, along with Stromboli island.
    Description: Published
    Description: 107823
    Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio
    Description: JCR Journal
    Keywords: Aeolian Archipelago ; Magnetic anomalies ; Strike slip Tectonics ; 04.05. Geomagnetism
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 55
    Publication Date: 2024-01-12
    Description: Subsurface geological reservoirs of natural hydrogen gas (H2), a clean fuel and energy vector, are currently a target for energy resource exploration. Such reservoirs can be revealed by the presence of H2 within soil, analogous to hydrocarbon seepage in petroleum systems. Nevertheless, defining the level of soil H2 that can indicate a potentially economic resource is currently impossible, and identifying geological H2 within soil-gas is challenging because H2 concentrations and the isotopic composition (δ2H) may overlap with the in-situ biological signature. In spite of these limitations, analogies to conventional hydrocarbon systems suggest that the presence of surface advective gas flows can reveal (unlike diffusion) a subsoil source and even pressurised gas accumulations of H2. Here, a massive release of H2 is reported from a CH4–H2 rich seep in Turkey, known as Chimaera, an emblematic example of H2 advection. The site represents the first case where a closed-chamber flux method was applied for H2 seepage. H2 advection at the site was clearly indicated by numerous gas vents and flames, and by the heterogeneous spatial distribution of pervasive, invisible exhalation (miniseepage), inducing rapid H2 concentration build-up within the chamber. H2 emission (∼10 ± 3 kg day−1, with the highest H2 emission factor reported, thus far, of ∼5000 kg km−2 day−1) is continuous and long lasting (flames have been documented for millennia) and, using an analogy for hydrocarbon seeps, may stem from pressurised accumulations. The Chimaera case is illustrative of how detecting soil H2 advection may help unravel surface (biological) vs. subsoil (geological) gas origins in cases where, in the absence of significant gas seepage, soil H2 concentrations are within the range of biological production (100-103 ppmv, e.g., as for “fairy circles” observed in several countries). Interpretations must, however, be supported by additional geochemical data and evaluations of potential biological H2 production within the surface ecosystem.
    Description: Published
    Description: 9172-9184
    Description: OSA5: Energia e georisorse
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 56
    Publication Date: 2024-01-12
    Description: Submarine methane-rich gas hydrates in ocean sediments are a potential atmospheric greenhouse gas and energy source. It is considered that microbial methane is generally autochthonous, produced in situ within the gas hydrate stability zone with low gas flux and pressure, while thermogenic gas is allochthonous, migrated from a deeper petroleum system, with higher gas flux and pressure and therefore potentially higher energy resource and environmental impact. Here, we report on the allochthonous nature of large microbial gas hydrate deposits in the Rakhine Basin, Bay of Bengal. An innovative and automatic tool, developed to analyze high-resolution three-dimensional seismic data, allowed to detect hundreds of thousands gas occurrences throughout a 2 km thick Pliocene-Pleistocene sedimentary sequence extending below the gas hydrate stability zone. A supercharged section matching the present-day optimum temperature for microbial methanogenesis was identified. Combining seismic and geochemical data of the Rakhine Basin gas system points to a dominant microbial nature of the gas. Stacked amplitude anomalies and vertical anomaly clusters demonstrate active free-phase gas migration towards the shallow gas hydrate stability zone. The Rakhine Basin gas hydrates are the ultimate seal for the entire petroleum system and represent a case of “frozen seepage” of microbial gas with relatively high flux and pressure.
    Description: Published
    Description: 106100
    Description: OSA5: Energia e georisorse
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 57
    Publication Date: 2024-01-12
    Description: The study of the oxidation state of lithospheric mantle-derived rocks allows modelling the deep cycle of volatiles (e.g., C, H, O, N and S) in the Earth’s interior, which in turn plays a role in magma genesis, metasomatism and volcanic degassing. At the oxygen fugacity (i.e., fO2) recorded by residual abyssal peridotites, volatile elements like carbon are predicted to be in the immobile form of graphite. However, the compilation of the redox state of worldwide-distributed continental xenoliths shows evidence of their oxidation and refertilization through time by deeply formed subduction-related metasomatic fluids. The analyses of fluid inclusions in mantle-derived minerals like olivine (or pyroxenes) represent a snapshot of the volatile circulation in depth, whose noble gases signature (He, Ar, Ne) is used to identify their possible source. This study aims to reconstruct the origin of mantle metasomatism underneath the Hyblean Plateau (Sicily, Italy) and its redox history through the investigation of spinel-peridotite nodules, combining fO2 estimates with noble gases and fluid inclusions chemistry from hand-picked olivine grains. We analyzed eight mantle xenoliths classified as spinel lherzolites and spinel harzburgites from the Valle Guffari (Hyblean Plateau, Sicily). The calculated logfO2 is higher than that of most cratonic xenoliths worldwide ranging between 0.28 and 1.27 log units above to the fayalite-magnetite-quartz (FMQ) reference buffer. Micro-Raman measurements on olivine grains with dendritic trails of (metasomatic) fluid inclusions reveal an assemblage made of Mg-Ca carbonates ± sulfide ± elemental sulfur ± CO2 in the most reduced sample, and Mg-Ca carbonates ± sulfates ± CO2 in the most oxidized sample, the latter associated with a silicate glass and (secondary) hydrous phases. Both assemblages are taken as evidence of the product of crystallization of deeply originated volatile-bearing silicate melts. Analyses of He, Ar, and Ne in olivine grains confirm the evidence of a mantle source reworked by metasomatic processes. Our data suggest that an initially residual Hyblean lithospheric mantle was affected by extensive oxidizing events at several depths caused by the interaction with slab-derived CO2-rich silicate metasomatic liquids.
    Description: Published
    Description: 107337
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Redox state ; Raman ; M¨ossbauer spectroscopy ; Noble gases ; Abyssal peridotites
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 58
    Publication Date: 2024-01-12
    Description: Petrology and fluid inclusions (FI) geochemistry are increasingly used in tandem to constrain the compositional features and evolution of the lithospheric mantle. In this study, we combine petrography and mineral chemistry with analyses of noble gases (He, Ne and Ar) and CO2 in olivine, orthopyroxene- and clinopyroxene-hosted FI, as well as radiogenic isotope (Sr-Nd-Pb) systematics of ultramafic xenoliths collected at La Grille volcano in Grande Comore Island, aiming at better characterizing one of the most enigmatic and controversial portions of the western Indian Ocean lithospheric mantle. Xenoliths have been divided in three groups on the basis of their textural features: Group 1 (Opx-bearing), Group 2 (Opx-free) and Group 3 (Cumulate). Overall, petrographic observations and mineral phase compositions indicate that the sampled lithospheric portion experienced variable degrees of melting (from 5% to 35%), recorded by Group 1 most refractory harzburgites and lherzolites, as well as modal metasomatic processes as evidenced by the crystallization of cpx at the expense of opx in Group 1 fertile lherzolites and wehrlite and by Group 2 xenoliths. Crystallization of slightly oversaturated basic silicate melts seems also to have occurred, as shown by Group 3 xenoliths. A positive trend between temperature and ƒO2 is evident, with Group 2 and 3 xenoliths testifying for hotter and more oxidised conditions than Group 1. The variability of the 4He/40Ar* ratio (0.02–0.39) in Group 1, significantly below typical values of a fertile mantle (4He/40Ar* = 1–5), can be explained by the variable degrees of partial melting coupled to metasomatic enrichment that may account for modifying 4He/40Ar*, as also indicated by the mineral composition. He-Ar-CO2 relationships support the presence of a metasomatic CO2-rich process post-dating the melt extraction and the cumulate formation. The air-corrected 3He/4He isotopic ratios (6.30 to 7.36 Ra) are intermediate between the MORB mantle signature (8 ± 1Ra) and the SCLM (6.1 ± 0.9 Ra). The Ne and Ar isotopic signatures (20Ne/22Ne, 21/Ne/22Ne and 40Ar/36Ar) are consistent with mixing between an air-derived component and a MORB-like mantle, supporting the hypothesis for a lithospheric origin of the Comoros magmas, and arguing against any deep mantle plume-related contribution. This is also corroborated by combining Ne with He isotopes, showing that La Grille ultramafic xenoliths are far from the typical plume-type compositions. Sr-Nd-Pb isotope systematics in opx and cpx from La Grille additionally support a MORB-type signature for the lithospheric mantle beneath the area.
    Description: Published
    Description: 107406
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Mantle xenoliths ; Noble gases ; Fluid inclusions ; Radiogenic isotopes
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 59
    Publication Date: 2024-01-12
    Description: In serpentinised peridotite and ultramafic rock systems, methane (CH4) origin is frequently considered abiotic, but variable microbial and thermogenic components can also exist. Typically, the origin of CH4 is studied using bulk, 13C/12C and 2H/H isotopic composition, molecular gas composition, occasionally radiocarbon (14C), microbiology and geological context. Recent advances in CH4-clumped isotope methods have yielded novel insights into the formation of CH4: nonetheless, their interpretation in natural gas samples is often uncertain and requires additional research. Here, we study the origin of the gas released in hyperalkaline (pH 〉 10) springs in the Ronda Peridotite Massifs (southern Spain), combining bulk and clumped CH4 isotopes with molecular gas composition, hydrochemical (Total Organic Carbon and Platinum Group Elements in water), geothermal and geo-structural data. Five springs analysed in 2014 have been re-examined for changes in gas chemistry over time, and three newly discovered gas-bearing springs are analysed for the first time. Regardless of whether springs have microbial or abiotic isotopic fingerprints, we find that bulk CH4 isotopes are fairly stable over a seven-year period. This suggests that the CH4 source(s) or postgenetic processes (such as oxidation and diffusion) have not undergone significant temporal changes. Major variations in H2 and CH4 concentrations in certain springs may be the result of changes in gas pressure and migration intensity. Paired CH4 clumped isotopes (Δ12CH2D2 - Δ13CH3D) were analysed in two bubbling springs, where the presence of CH4 can be interpreted as non-microbial based on 13C enrichment, absence of 14C, and the presence of ethane and propane. However, these isotopes are in disequilibrium, which prevents the quantification of the gas formation temperature. Within the Δ12CH2D2 - Δ13CH3D diagram, the data lie within both the microbialgenic zone, suggested by previous authors, and the abiotic zone that results combining data from laboratory gas synthesis and other natural gas samples. Therefore, attributing a microbial origin to CH4 based only on clumped isotopes is less definite than previously assumed. The amount of Total Organic Carbon appears to be correlated with the origin of CH4, as it is higher in 13C-depleted CH4 samples and lower in 13C-enriched samples. Palladium (Pd) and Rhodium (Rh) dissolved in water (the more soluble Platinum Group Elements) can be a proxy for the chromitite ore deposits contained in plagioclase tectonite layers throughout the investigated area, which may act as catalysts for abiotic CO2 hydrogenation. Clumped isotope disequilibrium and the reported absence of diffuse CH4-bearing fluid inclusions in the peridotites appear to rule out high temperature gas genesis in post-magmatic inclusions. These observations, along with the moderate temperatures at the base of the peridotite massifs and the consistent occurrence of gas along tectonic contacts between serpentinised (H2-bearing) peridotite and carbon-bearing rocks, are compatible with the theory of low-temperature CO2 hydrogenation.
    Description: Published
    Description: 121799
    Description: OSA5: Energia e georisorse
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 60
    Publication Date: 2024-01-19
    Description: The complex tectonic evolution of the Alps-Apennines transition zone in NW Italy is still a matter of debate. In this work, we analyze the 2021–2022 seismic sequences around Genoa to understand how convergence between Africa and Europe is presently accommodated across the Alps-Apennines transition zone. The map-view distribution of HypoDD-relocated seismic events reveals a NE-SW alignment for the Savignone seismic sequence, and NNW-SSE alignments for the Borzonasca and Bargagli sequences. The Borzonasca seismic sequence plots in correspondence of the Villalvernia-Varzi-Ottone Fault, which is often considered as the boundary between the Alps and the Apennines, whereas no seismicity is documented along the Sestri-Voltaggio Fault. The main-shock focal solutions are invariably strike-slip, with near-vertical NNW-SSE and NE-SW to ENE-WSW nodal planes. The evident earthquake alignments in the study area mark active, km-scale fault planes in the upper crust, pointing to a scenario of distributed strike-slip deformation in the transition zone between the Alps and the Apennines. The NE-SW faults are inherited structures that underwent major Neogene rotations and are no longer suitably oriented to accommodate the northward motion of Adria relative to Europe. The Bargagli seismic sequence may reflect the formation of new NNW-SSE strike-slip faults in the upper crust that are more suitably oriented to accommodate the present-day stress field, consistent with the seismotectonic framework outlined by recent works in the nearby regions of the Adria-Europe plate-boundary zone. Our results highlight the important role of strike-slip faulting in the Adria-Europe plate boundary zone not only in the past, but also during its present-day evolution.
    Description: Published
    Description: 230101
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 61
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    Elsevier
    Publication Date: 2024-01-19
    Description: Stress fields may exhibit variegated patterns, especially in volcanic areas where several processes superimpose their effects in space and time. The comprehension of such patterns may not be straightforward to investigate. This work investigates the pattern of the crustal stress in the area of Mt. Etna Volcano (Sicily, Italy). This has been possible through a collection of more than 800 stress indicators derived from seismological and volcanological/geological information. In particular, the type of collected data allows to consider, for the first time in this area, two different temporal steps in the evolution of Etna volcano: the present-day and the previous volcanic phase at 15 ka. Results indicate a transition between a background shallow NW-SE tensional regime and a deep SW-NE compressional one that occurs between 6 and 16 km depth and which well fits with the present-day geodynamic framework of the area. The occurrence of small-scale lateral variations is interpreted as the second-order effect of the structures of the active front buried beneath the volcano, to the volcano loading, and to the feeding system. The temporal variations in the area surrounding the volcano suggest a major rearrangement of the background stress field evidenced by the swap between minimum and maximum horizontal stress directions. Conversely, during the same period, the stress pattern in the exact correspondence of the volcanic edifice showed to be stable and with a radial arrangement. Such coherence would support the literature which suggests a long-term inflation process started at least 15 kyr ago.
    Description: Published
    Description: 102017
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 62
    Publication Date: 2024-01-19
    Description: In this study, we discuss the extra-value of polarimetric information in observing the lava flow. Dualpolarimetric Synthetic Aperture Radar (SAR) measurements are processed using a polarimetric change detector that, instead of looking at the variation of the backscatter intensity between a pair of images collected before and after the event, looks at changes in the polarimetric scattering behavior. We demonstrate that the scattering changes detected by the proposed polarimetric approach well-correlate with the footprint of the lava flow provided by external sources. In addition, we also compare the performance of the polarimetric change detector with conventional single-polarization metrics showing that the former one always outperforms the incoherent single-polarization measurements. To further demonstrate the robustness of the polarimetric change detectors, we selected two test cases that refer to vulcanic eruptions calling for completely different environments. The first one, related to the Etna volcano, calls for a lava flow over a vegetation-free environment; the second one is related to the Nyiragongo volcano and calls for a lava flow in a vegetated environment. Experimental results show that the polarimetric change detectors automatically adapt to the changing environment outperforming the single-polarization detectors.
    Description: Published
    Description: 103471
    Description: OSV3: Sviluppo di nuovi sistemi osservazionali e di analisi ad alta sensibilità
    Description: JCR Journal
    Keywords: Lava flow ; Change detection ; Polarimetric SAR ; Sentinel-1
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 63
    Publication Date: 2024-01-19
    Description: We investigate the response of the topside ionosphere, auroral and polar sectors, to the forcing of the geospace during September 2017. Specifically, we aim at characterizing such a response in terms of the involved spatial scales and of their intensification during the different auroral and polar cap activity conditions experienced in the selected month, that is characterized by severe geomagnetic storm conditions. For our purposes, we leverage on and compare various in situ plasma density data products provided by the Swarm constellation of the European Space Agency (ESA). The spatio-temporal variability of the involved scales in the plasma density observation is featured through the application of the Fast Iterative Filtering (FIF) signal decomposition technique and, for the first time in the ionospheric field, of a FIF-derived dynamical spectrum called ‘‘IMFogram”. The instantaneous time-frequency representation provided through the IMFogram illustrates the time development of the multi-scale processes with spatial and temporal resolutions higher than those obtained with traditional signal processing techniques. To demonstrate this, the IMFogram is tested against Fast Fourier and Continuous Wavelet Transforms. With our fine characterization, we highlight how scale cascading and intensification processes in the plasma density observations follow the ionospheric currents activity, as depicted through the auroral activity and polar cap indices, and through the field-aligned currents data product provided by Swarm.
    Description: Published
    Description: 5490-5502
    Description: OSA3: Climatologia e meteorologia spaziale
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 64
    Publication Date: 2024-01-17
    Description: We have found a previously unreported later seismic phase in seismograms of European seismic stations from intermediate-depth and deep earthquakes of the Southern Tyrrhenian subduction zone. We observe this phase at stations from 6 to 9◦ from the epicentre, towards north. Only seismograms of earthquakes located in a welldefined region of the slab, in the depth range of 215–320 km, show the later x-phase. In this work, we describe the nature and possible origin of this phase, and we provide a simple 2D model to explain the observed arrival times. Our analyses reveal that the x-phase propagates downward in a high velocity layer, possibly located within the deepest part of the slab. We suggest that this layer reveals the presence of the dense hydrous magnesium silicate phase A, introduced from petrological laboratory experiments, inferred to carry water in the upper mantle and predicted to be found in cold subduction zones.
    Description: Published
    Description: 229919
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: Southern Tyrrhenian subduction zone ; Mineral phase A ; Intermediate and deep seismicity ; Waveforms analyses ; Later seismic arrival/phase ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 65
    Publication Date: 2024-01-18
    Description: Changes in seismicity with time and location are diagnostic signals for understanding the dynamics of volcanic unrest. We used these signals at the Campi Flegrei caldera, in southern Italy, to investigate how structural changes have determined three styles of unrest since 1982, distinguished by a ground uplift (measured at Pozzuoli, near the centre of the caldera) of 178 cm in 1982–84; a subsidence of 93 cm in 1985–2005; and an uplift of 118 cm between 2005 and November 2023. Double-difference seismic locations and concentrations of seismic energy release have revealed impermeable horizons that correspond to the cap rock and self-sealed base of the geothermal system at depths of 1.5 and 3 km, respectively. Most earthquakes have been shallower than 3 km, consistent with the brittle upper crust being stretched over a zone of pressurization below the geothermal system. The 1982–84 uplift decayed after a major seismic swarm on April 1st, 1984, breached the lower impermeable horizon, which increased the flux of escaping gas and reduced the source pressure. Continued gas escape promoted subsidence until the lower horizon had resealed itself and initiated a new episode of uplift while gas from depth re-accumulated beneath. Compared with 1982–84, a greater proportion of recent seismicity has occurred at shallower depths below the actively degassing fumaroles of Solfatara-Pisciarelli, north-east of Pozzuoli. The associated high seismic b-values, between 1 and 2, are consistent with high fluid pressures and, hence, with locations more favourable to fracturing. Continued uplift may thus persist until fracturing of the shallow crust allows faster rates of gas release and depressurization of the pressure source.
    Description: Published
    Description: 118530
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Campi Flegrei caldera ; Hydrothermal system ; Volcanic unrest ; Seismicity ; Fluid circulation ; Brittle/ductile transition
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 66
    Publication Date: 2024-01-22
    Description: Biomagnetostratigraphic studies carried out at the Ypresian/Lutetian (Eocene) Gorrondatxe section solved major chronostratigraphic calibration discrepancies that had existed for several decades. The new calibration resulted in the definition of the Global Stratotype Section and Point (GSSP) for the Lutetian Stage at the Gorrondatxe layer containing the lowest occurrence (LO) of the calcareous nannofossil Blackites inflatus (base of Subzone CP12b). However, subsequent studies cast some doubt on the reliability of the Gorrondatxe biomagnetostratigraphic data and, consequently, the appropriateness of the criterion used for the definition of the Lutetian GSSP. In order to address the issues raised, the biomagnetostratigraphy of the Gorrondatxe section was revisited and an additional cyclostratigraphic analysis was undertaken using magnetic susceptibility data series. The present study shows that the Gorrondatxe biomagnetostratigraphy is reliable. The spectral analyses showed the dominance of precession (~20 ky) and short (~100 ky) eccentricity forcing on sedimentation, but the influence of obliquity (~38 and ~55 ky) cycles was also detected and modulation by long (405 ky) eccentricity cycles was deduced. The succession was tuned to the 49.122-48.084 Ma interval and the astronomical ages obtained for a significant number of biomagnetostratigraphic events compared well with those derived from other studies. One of the exceptions is the LO of B. inflatus, which seems to be older in Gorrondatxe than in the Mediterranean and Western Atlantic areas. This diachrony most likely also delayed the LO of B. inflatus in historical reference sections of the North Sea area, rendering previous claims that the Lutetian GSSP caused some historical Lutetian sections to be Ypresian in age invalid. In fact, the definition of the base of the Lutetian Stage by the LO of B. inflatus at Gorrondatxe, now astronomically age dated at 48.455 Ma, best guarantees that the original concepts of the Ypresian and Lutetian historical stratotypes are maintained. Combined with secondary biomagnetostratigraphic marker events and an astronomically tuned cyclostratigraphy, the Ypresian/Lutetian Gorrondatxe section provides the globally significant chronostratigraphic reference model expected of any GSSP.
    Description: Published
    Description: 111669
    Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 67
    Publication Date: 2024-01-22
    Description: The Tibetan Plateau is growing by both vertical uplift and horizontal extension. It is a continuing debate how the Tibetan Plateau interacts with its surrounding plates and blocks. Due to intense tectonic activity, which produced catastrophic earthquakes, the tectonic zone between the northeast margin of the horizontal extending Tibetan Plateau and the stable Ordos Block has garnered considerable interest. This study investigated the spatial distribution of gas geochemical anomalies (e.g., high flux of CO2 in correspondence of the main faults) at regional scale together with the seismic tomography in correspondence of this tectonic zone with the aim to figure out the domain of convergent boundary between the Ordos block and Tibetan plateau, and trace the tectonic discontinuities which are able to transfer fluids through the crustal layers between the two main geological units. From northwest to southeast, obvious difference of spatial distributions of geochemical and geophysical features in the tectonic zone between the northeast margin of the Tibetan Plateau and the Ordos Block is inferred. The northeast area (Zone A) is dominated by thrust and strike-slip faults with clear velocity boundary underneath, where low crack density (ε), saturation rate (ξ) and Poisson’ ratio (σ) in the middle-lower crust coincided with the low values of heat flow and CO2 emissions, tectonic compression and regional locked-fault can be inducements. The southeast area (Zone C) is dominated by extensional tectonics with roughly E-W fast-velocity direction (FVD) of P-wave azimuthal anisotropy, where high permeability and porosity can be deduced from crustal high ε, ξ and relatively high σ anomalies, resulting in high heat flow, CO2 concentrations and fluxes at the surface, and predominantly crustal-derived gases. The intermediate area (Zone B) also dominated by thrust and strike-slip faults is an extraordinary zone, where intensely locked-fault were clearly revealed, while the predominant anisotropic FVDs in the middle crust changed obviously, more contribution of shallow gas component was detected, and CO2 flux, heat flow, and regional ε, ξ, and σ in the upper crust were higher, compared with those in Zone A, which indicated the regional crushing fragmentation underneath Zone B. The adopted multidisciplinary approach demonstrated that Zone B is the convergent boundary between the Tibetan Plateau and the Ordos Block.
    Description: Published
    Description: 121386
    Description: OST3 Vicino alla faglia
    Description: JCR Journal
    Keywords: fluids ; earthquakes ; helium ; Tibetan plateau
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 68
    Publication Date: 2024-01-22
    Description: The recently selected missions to Venus have opened a new era for the exploration of this planet. These missions will provide information about the chemistry of the atmosphere, the geomorphology, local-to-regional surface composition, and the rheology of the interior. One key scientific question to be addressed by these future missions is whether Venus remains volcanically active, and if so, how its volcanism is currently evolving. Hence, it is fundamental to analyze appropriate terrestrial analog sites for the study of possibly active volcanism on Venus. To this regard, we propose Mount Etna - one of the most active and monitored volcanoes on Earth - as a suitable terrestrial laboratory for remote and in-situ investigations to be performed by future missions to Venus. Being characterized by both effusive and explosive volcanic products, Mount Etna offers the opportunity to analyze multiple eruptive styles, both monitoring active volcanism and identifying the possible occurrence of pyroclastic activity on Venus. We directly compare Mount Etna with Idunn Mons, one of the most promising potentially active volcanoes of Venus. Despite the two structures show a different topography, they also show some interesting points of comparison, and in particular: a) comparable morpho-structural setting, since both volcanoes interact with a rift zone, and b) morphologically similar volcanic fields around both Mount Etna and Idunn Mons. Given its ease of access, we also propose Mount Etna as an analog site for laboratory spectroscopic studies to identify the signatures of unaltered volcanic deposits on Venus.
    Description: Published
    Description: 115959
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 69
    Publication Date: 2024-01-22
    Description: Tetrapod diversity in Permian terrestrial ecosystems of southwestern Europe is poorly recorded by bone specimens, but it is better represented by an important tetrapod ichnological record that is relevant to our understanding of vertebrate communities in the equatorial Pangaea. Herein, two tetrapod ichnoassociations from three new ichnosites, within Cisuralian and Guadalupian volcanosedimentary terrestrial successions (the Lower Red Unit and the Upper Red Unit deposits) of the Castellar de n’Hug sub-basin (Catalan Pyrenees, NE Iberian Peninsula) are presented. Tetrapod ichnology in combination with stratigraphic and facies analyses permit a characterisation of these ecosystems. The sedimentary deposits show an evolution from fluvial meandering systems to playa-lake floodplains, denoting increased aridification and seasonality under a monsoonal regime. The ichnofossil record shows how tetrapod assemblages shifted from a prevalence of non-amniotes and eureptiles to a dominance of therapsids, eureptiles and parareptiles. The reported ichnotaxa are distributed in two ichnoassociations. The first preserves Batrachichnus, Dromopus, Hyloidichnus, Characichnos and an indeterminate tetrapod morphotype, whereas the second is defined by the presence of Dromopus, Hyloidichnus, Brontopus antecursor and Pachypes. The stratigraphically older ichnoassociation, preserved in volcaniclastic and fluvial deposits, presents features of the early Erpetopus biochron, whereas the stratigraphically younger one, preserved in playa-lake deposits, is constrained to the Brontopus sub-biochron. Biostratigraphic and magnetostratigraphic data suggest a late Cisuralian to middle Guadalupian age for the whole succession. The ichnoassemblage highlights a palaeobiogeographical connection between the Pyrenean Basin and other peri-Tethyan basins, which allows us to expand our knowledge about the palaeoecology and palaeobiodiversity of the Cisuralian to Guadalupian terrestrial ecosystems.
    Description: Published
    Description: 111837
    Description: OSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territorio
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 70
    Publication Date: 2024-01-31
    Description: Thousands of artificial (‘human-made’) structures are present in the marine environment, many at or approaching end-of-life and requiring urgent decisions regarding their decommissioning. No consensus has been reached on which decommissioning option(s) result in optimal environmental and societal outcomes, in part, owing to a paucity of evidence from real-world decommissioning case studies. To address this significant challenge, we asked a worldwide panel of scientists to provide their expert opinion. They were asked to identify and characterise the ecosystem effects of artificial structures in the sea, their causes and consequences, and to identify which, if any, should be retained following decommissioning. Experts considered that most of the pressures driving ecological and societal effects from marine artificial structures (MAS) were of medium severity, occur frequently, and are dependent on spatial scale with local-scale effects of greater magnitude than regional effects. The duration of many effects following decommissioning were considered to be relatively short, in the order of days. Overall, environmental effects of structures were considered marginally undesirable, while societal effects marginally desirable. Experts therefore indicated that any decision to leave MAS in place at end-of-life to be more beneficial to society than the natural environment. However, some individual environmental effects were considered desirable and worthy of retention, especially in certain geographic locations, where structures can support improved trophic linkages, increases in tourism, habitat provision, and population size, and provide stability in population dynamics. The expert analysis consensus that the effects of MAS are both negative and positive for the environment and society, gives no strong support for policy change whether removal or retention is favoured until further empirical evidence is available to justify change to the status quo. The combination of desirable and undesirable effects associated with MAS present a significant challenge for policy- and decision-makers in their justification to implement decommissioning options. Decisions may need to be decided on a case-by-case basis accounting for the trade-off in costs and benefits at a local level.
    Repository Name: EPIC Alfred Wegener Institut
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  • 71
    Publication Date: 2024-01-26
    Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Erosion of permafrost coasts due to climate warming releases large quantities of organic carbon (OC) into the Arctic Ocean. While burial of permafrost OC in marine sediments potentially limits degradation, resuspension of sediments in the nearshore zone potentially enhances degradation and greenhouse gas production, adding to the “permafrost carbon feedback.” Recent studies, focusing on bulk sediments, suggest that permafrost OC derived from coastal erosion is predominantly deposited close to shore. However, bulk approaches disregard sorting processes in the coastal zone, which strongly influence the OC distribution and fate. We studied soils and sediments along a transect from the fast‐eroding shoreline of Herschel Island—〈jats:italic〉Qikiqtaruk〈/jats:italic〉 (Yukon, Canada) to a depositional basin offshore. Sample material was fractionated by density (1.8 g cm〈jats:sup〉−3〈/jats:sup〉) and size (63 μm), separating loose OC from mineral‐associated OC. Each fraction was analyzed for element content (TOC, TN), carbon isotopes (δ〈jats:sup〉13〈/jats:sup〉C, Δ〈jats:sup〉14〈/jats:sup〉C), molecular biomarkers (〈jats:italic〉n〈/jats:italic〉‐alkanes, 〈jats:italic〉n〈/jats:italic〉‐alkanoic acids, lignin phenols, cutin acids), and mineral surface area. The OC partitioning between fractions changes considerably along the transect, highlighting the importance of hydrodynamic sorting in the nearshore zone. Additionally, OC and biomarker loadings decrease along the land‐ocean transect, indicating significant loss of OC during transport. However, molecular proxies for degradation show contrasting trends, suggesting that OC losses are not always well reflected in its degradation state. This study, using fraction partitioning that crosses land‐ocean boundaries in a way not done before, aids to disentangle sorting processes from degradation patterns, and provides quantitative insight into losses of thawed and eroded permafrost OC.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 72
    Publication Date: 2024-01-26
    Description: Lava flows associated with effusive volcanic eruptions require accurate modelling in order to forecast potential paths of destruction. This study presents a new depth-averaged model that overcomes the classical shallow water hypothesis by incorporating several enhancements, allowing for a more precise representation of the flow dynamics and behaviour: (i) a parabolic profile which captures the vertical variations in velocity within the flow; (ii) a non-constant vertical profile for temperature, enabling a more realistic representation of thermal gradients within the flowing lava; (iii) a viscoplastic temperature-dependent viscosity model to account for the non-Newtonian behaviour of lava; (iv) a transport equation for temperature accounting for the thermal heat exchanges with the environment and the soil. The first two modifications allow us to describe, under reasonable assumptions, the vertical structure of the flow, and for this reason, we put our model in the class of 2.5D models. To assess the performance of our modified model, comprehensive benchmark tests are conducted using both laboratory experiments and real-world lava flow data related to the 2014–2015 Pico do Fogo, Cape Verde, effusive eruption. The benchmarking analysis demonstrates that this model accurately reproduces, with short execution times, essential flow features such as flow front advancement and cooling processes.
    Description: Published
    Description: 107935
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Lava flows ; numerical model ; 04.08. Volcanology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 73
    Publication Date: 2024-01-26
    Description: Volcanic crisis exercises are usually run to test response capabilities, communication protocols, and decision-making procedures by agencies with responsibilities to cope with scenarios of volcanic unrest with inherent uncertainty, such as volcano observatories and/or civil protection authorities. During the last decades, the use of questionnaires has been increased to evaluate people’s knowledge on volcanic hazards and their perception of risk, to better understand their preparedness to respond to emergency measures plans. In this paper, we present a study carried out within the European Network of Observatories and Research Infrastructures for Volcanology project (EUROVOLC) focused on extracting information on the experience gained during volcanic-crisis exercises by the project’s participants and beyond. An open-ended question questionnaire was firstly distributed for a survey within the project community. Through the results obtained, we developed a user-friendly online multi-choice questionnaire that was submitted to the volcanological communities within and outside EUROVOLC. Analyzing the answers to the online questionnaire, we extracted a prototype checklist for guiding the design of such exercises in the future. Our results confirm this type of survey as a very useful tool for gathering information on participants’ experience and knowledge, able to understand which data and information may be useful when designing exercises for scientists, emergency managers and decision makers. In particular, the main lessons learnt regard the need i) to increase training activities involving people exposed to volcanic hazards and media, ii) to improve external communication tools (between players and public/media), equipment and protocols and iii) to better define decision-makers’ needs.
    Description: Published
    Description: 107850
    Description: OSV4: Preparazione alle crisi vulcaniche
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 74
    Publication Date: 2024-02-01
    Description: The Northern Apennines thrust front in the Po basin exhibits active blind thrusts and associated anticlines, with some anticline crests either emerging or shallowly buried beneath late Pleistocene continental deposits. This study focuses on the outcropping San Colombano Structure and its buried neighbouring Casalpusterlengo-Zorlesco Structure, representing thrust-controlled anticlines in the central part of the Po basin. We reconstruct the Pleistocene evolution of these anticlines by integrating previously published surface geological maps and subsurface geological constraints from geophysical data and boreholes. We performed a trishear inversion of the deformation observed after the decompaction of the sediments. We used the solutions of the trishear inversion to compute the probabilistic distribution of slip rates over distinct time intervals. Our findings align with previous estimations of long-term slip rates in the Po Plain during the Quaternary, revealing rates of approximately 0.63 mm/yr and 0.53 mm/yr over the past 2.4 Myr for the San Colombano and Casalpusterlengo-Zorlesco Structures, respectively. The analysis of stratigraphic markers unveils a general decrease in faults activity during the Pleistocene, with slip rates around 0.2–0.3 mm/yr in the last 0.3 Myr, along with a diverse evolution of the thrust faults governing the two anticlines. Specifically, the activity rates of the San Colombano Structure supersede that of the Casalpusterlengo-Zorlesco Structure during the Middle to Late Pleistocene, implying an out-of-sequence propagation of the San Colombano ramp-anticline in the Late Pleistocene along an oblique right-lateral transfer zone. Incorporating a probabilistic approach in slip rates calculation provides a more comprehensive handling of uncertainties. This attribute is pivotal in seismic hazard assessment analyses and understanding complex fault systems' tectonic evolution.
    Description: Published
    Description: 230227
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: San Colombano thrust ; Quaternary tectonics ; Slip rates ; Trishear inversion ; Sediment compaction ; 04.07. Tectonophysics ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 75
    Publication Date: 2024-01-24
    Description: Many gene families are shared across the tree of life between distantly related species because of horizontal gene transfers (HGTs). However, the frequency of HGTs varies strongly between gene families and biotic realms suggesting differential selection pressures and functional bias. One gene family with a wide distribution are FIC-domain containing enzymes (FicDs). FicDs catalyze AMPylation, a post-translational protein modification consisting in the addition of adenosine monophosphate to accessible residues of target proteins. Beside the well-known conservation of FicDs in deuterostomes, we report the presence of a conserved FicD gene ortholog in a large number of protostomes and microbial eukaryotes. We also reported additional FicD gene copies in the genomes of some rotifers, parasitic worms and bivalves. A few dsDNA viruses of these invertebrates, including White spot syndrome virus, Cherax quadricarinatus iridovirus, Ostreid herpesvirus-1 and the beetle nudivirus, carry copies of FicDs, with phylogenetic analysis suggesting a common origin of these FicD copies and the duplicated FicDs of their invertebrate hosts. HGTs and gene duplications possibly mediated by endogenous viruses or genetic mobile elements seem to have contributed to the transfer of AMPylation ability from bacteria and eukaryotes to pathogenic viruses, where this pathway could have been hijacked to promote viral infection.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 76
    Publication Date: 2024-01-23
    Description: We investigate the presence of the quasi-Love wave (qL) at 51 seismic stations of a temporary seismic network across the western Arabia-Eurasia collision zone. We quantify the intensity of the qL observations from the April 12, 2014 Solomon Islands earthquake by calculating the peak-to-peak amplitude ratios of the qL and Love waves, and compare them with predicted qL intensities from previous shear-wave splitting results. We determine the polarity, timing, and period-dependence of the qL observations within the period range of 50–100 s. Our analysis reveals that the qL observations at stations in the Zagros and Alborz mountain belts exhibit opposite characteristics. In contrast to the Alborz stations, the intensity of qL observations at the Zagros stations exhibits relatively negligible dependence on the period, while their receiver-scatterer distances are considerably period dependent. We approximately locate the anisotropic gradients that generate the qL waves. Our results suggest that a lithospheric gap is responsible for the shallow and abrupt variation in the belt-parallel trend of fast-axis orientations in the westernmost part of the Zagros. Additionally, the period/depth dependence of the anisotropic gradients along the boundary between the central Zagros and central Iran provides insight into the variation in the downward dip of the Arabian lithosphere. The anisotropic gradient located to the north of the Doruneh fault in eastern Iran indicates its role as a major shear zone and lithospheric boundary. Finally, we observe that the spatial distribution of the anisotropic gradient in northeastern Iran matches the higher strain rate areas in the Kopet Dagh Mountains, suggesting coupling between the lithospheric mantle and crust in that region.
    Description: Published
    Description: 101989
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 77
    Publication Date: 2024-01-25
    Description: A multidisciplinary approach including archaeological, geophysical, and geological/geomorphological surveys provided pieces of evidence that allowed us to identify the Sibari fault zone (SFZ) in Northern Calabria (Italy). The SFZ runs in a ~ NE-SW direction for a length of ~18 km from the Ionian coastline to Terranova da Sibari and has an oblique normal-dextral kinematics. The envelope of the SFZ is derived from several direct and indirect evidence resulting in subparallel and locally en-echelon fault traces over a maximum 500 m-wide band, running at different elevations across hills and flat lands. The SFZ was active since at least the Middle-Upper Pleistocene, producing faulting of alluvial deposits, marine terraces, drainage incisions, and the archaeological structures of Sybaris. Given the fault length and assuming a seismogenic behavior, the SFZ is a primary earthquake source possibly producing moderate to large earthquakes (M ≥ 6). We calculated the average slip rates along the SFZ based on the ages and on the accumulated displacements of offset streams and marine terraces. The estimates are of 0.05–0.18 mm/yr and 0.41–0.70 mm/yr for vertical and dextral slip, respectively. Based on both the measured (min. 30 cm) and the expected value (av. 40 cm) of lateral slip per event, we infer an average recurrence for surface faulting events on the SFZ of about 700–1000 yrs. The most recent surface faulting earthquake occurred on the fault is dated 1300–1100 yrs. ago, highlighting that the elapsed time approaches the estimated average recurrence. Considering these findings, the newly recognized SFZ should be included among the faults that contain a potential seismic hazard in this poorly known portion of the Ionian sector of northern Calabria.
    Description: Published
    Description: 230214
    Description: OST2 Deformazione e Hazard sismico e da maremoto
    Description: JCR Journal
    Keywords: Active faults of Italy ; Seismic hazard ; Offset streams ; Displaced marine terraces ; Sybaris archaeological site ; 04.04. Geology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 78
    Publication Date: 2024-01-29
    Description: After eight decades since its discovery in 1939, new investigations have been undertaken at Grotta Guattari (Latium, central Italy), a coastal cave by the Tyrrhenian Sea coast and one of the iconic sites of the Italian prehistory, as it yielded an almost complete skull and other remains of Neanderthals. The new excavations of the innermost and untouched cave deposits resulted in an outstanding amount of mammal bones, 40 out of which attributable to Neanderthal, including new large portions of cranial remains. Preliminary taphonomic hints and the collected stratigraphic evidence strongly indicate that the impressive accumulation of the large mammal bones was the work of spotted hyena, in a period in which human frequentation was really sporadic or even completely absent. The new acquired U/Th chronology of Grotta Guattari speleothems provided new constraints for reconstructing the sedimentary and paleoenvironmental history of the archaeological successions and human remains. The accumulation of terrestrial sediments started at ~112 ka, immediately after the end of the Last Interglacial sea-level highstand (~116 ka). However, the hyena frequentation, and thus the bone accumulations, occurred several thousands of years after and lasted for a very short time interval, precisely between slightly before 66 ka and 65 ka. The cave became abandoned by hyena after ~65 ka and before ~59 ka, because of the cave obstruction and/or the altered environmental conditions related to the Heinrich Event 6 (~64 e60 ka). The regional paleoclimatic records indicate severe conditions during the short interval of the hyena frequentation. In contrast, though providing evidence of open and arid environments, the faunal assemblage and the pollen from Grotta Guattari reveal that the local conditions were less severe, likely because of the mitigating effect of the Tyrrhenian Sea. In the framework of the Italian findings, Grotta Guattari results the richest and better chronologically constrained site of Neanderthal remains, posing it as one of the rare sites of the European prehistory that allows putting into the context an extraordinary large sample of the population of Neanderthals, and of other large mammals, in a very narrow and precisely dated temporal interval of the early Pleniglacial
    Description: Published
    Description: 108132
    Description: OSA2: Evoluzione climatica: effetti e loro mitigazione
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 79
    Publication Date: 2024-01-29
    Description: A multiproxy record from a stalagmite collected from Torgashinskaya Cave (Southern Siberia, Russia) and growing between ca. 6 and 3.8 ka shows evidence for regional climatic changes occurring at ca. 5 ka. Interpretation of stable isotope ratios (δ18O and δ13C) and fluorescence data (intensity and wavelength of the emitted fluorescence) suggests that the interval between ca. 5 and 4.2 ka was generally warmer and drier than the interval between ca. 6 and 5 ka. The observed bipartitioning of the climate, attributable to the so-called ‘middlelate Holocene transition’, has a striking similarity to changes in K+ and Na+ concentration of Greenland ice cores (taken as indicators of the strength of the Siberian High and Icelandic Low, respectively), in the abundance of hematite-stained grains in subpolar North Atlantic sediments and, to lesser extent, in the summer Asian monsoon intensity deduced by δ18O from Chinese speleothems. In particular, the δ18O record at Torgashinskaya Cave can be interpreted as mostly driven by temperature changes. Besides several episodes of drift towards higher temperatures, it also strongly suggests the presence of short cooling events centered at 4.1+0.08/-0.07, 4.85+0.05/-0.06, 5.1+0.09/-0.09, 5.3+0.08/-0.07 and 5.8+0.12/-0.13 ka. Notably, the last three such events are in very good correspondence with spikes in the K+ and Na+ concentration of Greenland ice cores. Instead, the cooling around 4.1 ka could be the local response to the 4.2 event, a cold/dry episode identified in several records in the Northern Hemisphere. This suggests that δ18O of speleothem calcite from this area could be a useful proxy for defining the evolution of the Siberian High and its effect on the wider regional climate.
    Description: Published
    Description: 108355
    Description: OSA2: Evoluzione climatica: effetti e loro mitigazione
    Description: JCR Journal
    Keywords: Stable isotopes ; Fluorescence ; Speleothems ; Siberian high ; Holocene ; Permafrost ; Paleoclimate ; 4.2 event
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 80
    Publication Date: 2024-01-29
    Description: The current rapid change of the Earth’s climate has resulted in an increasing interest for the past warm periods as potential long-term scenarios of the effects of the present global warming. The last such a period occurred 129–116 ka, known as the Last Interglacial (LIG), when the continental ice volume was significantly smaller than present, leading to a global sea-level (GSL) higher than present one. Detailed morpho-stratigraphic data, supported by a robust U/Th chronology, from Grotta delle Capre, central Italy, provided new chronological insights on the relative sea-level (RSL) dynamic during the LIG in the Mediterranean region. Our results indicate that, on Tyrrhenian Sea coasts of the central Italy, after having stationed at ~9 m a.s.l., the LIG RSL fell at an elevation 〈3 m a.s.l. as early as before 123 ka, and then no longer rose above this elevation either during the later stages of the LIG or afterwards. The results match previous studies based on U/Th dating of terrestrial limiting points from Grotta Infreschi, ~200 km SE from Grotta delle Capre along the same Tyrrhenian Sea coasts, and are in agreement with the Red Sea RLS and GSL records and the probabilistic LIG sea level assessments based on globally distributed records. On the other hand, our reconstruction is not supported by implications of U/Th dating of corals and phreatic overgrowth on speleothems from the Balearic Island of Mallorca. Such an inconsistency in the overall knowledge around the LIG RSL reconstruction results in a high uncertainty in modelling the ice and sea-level dynamic during this warm period, which needs to be reduced through more and more highresolution, stratigraphic and chronological investigations of the morphological and sedimentary sea-level records.
    Description: Published
    Description: 104321
    Description: OSA2: Evoluzione climatica: effetti e loro mitigazione
    Description: JCR Journal
    Keywords: Last Interglacial ; relative sea level ; U/Th chronology ; Terrestrial limiting points ; Mediterranean
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 81
    Publication Date: 2024-02-02
    Description: Short-term interaction of magma with crustal carbonates can affect a volcano's eruptive style and drive even low-viscosity magmas toward large explosive eruptions. Only a few studies have focused on short-term magma-carbonate interaction under controlled laboratory conditions and the physical processes behind the experimental observations are still poorly understood. In this work, we present the first numerical modelling study of short-term magma-carbonate interaction and provide an interpretative framework for experimental and field observations. We developed thermodynamic and dynamic models for carbonate dissolution and mixing and mingling between contaminated magma pockets and host magma. We find that mixing and mingling can play a central role in modulating the efficiency of volatile exsolution. The increasing viscosity of the host melt slows down melt mingling and hence the mixing process, limiting volatile exsolution. Less efficient mixing and mingling could allow the fingerprints of short-term magma-carbonate interaction to be preserved in volcanic and intrusive rocks. Finally, we highlight that the mechanism and timescale of magma-carbonate interaction open a key question about the anomalous high mobility of CaO during carbonate dissolution.
    Description: Published
    Description: 118592
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
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  • 82
    Publication Date: 2024-02-07
    Description: It is well known that space weather can cause significant disruptions to modern communications and navigation systems, leading to increased safety risks, economic losses, and reduced quality of life. Operators of critical infrastructures (both national and international) are also increasingly aware that extreme space-weather events can have severe impacts on their systems. For example, strong ionospheric disturbances can degrade, and sometimes deny access to satellite positioning, navigation, and timing services, central to the operation of many infrastructures. The mitigation of the effects of space weather on technical systems on the ground and in space, and the development of possible protective measures, are therefore of essential importance. We discuss how space weather drives a wide variety of ionospheric phenomena that can disrupt communications and navigation systems and how scientific understanding can help us to mitigate those effects. We also provide recommendations on further research and collaboration with industrial and governmental partners, which are essential for the development and operation of space weather services.
    Description: In press
    Description: OSA3: Climatologia e meteorologia spaziale
    Description: JCR Journal
    Keywords: Radio communication ; navigation ; satellite positioning ; broadcast ; ionosphere ; radio propagation ; 01.02. Ionosphere
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 83
    Publication Date: 2024-02-14
    Description: Some of the most CO2-rich magmas on Earth are erupted by intraplate ocean island volcanoes. Here, we characterise olivine-hosted melt inclusions from recent (〈10 ky) basanitic tephra erupted by Fogo, the only active volcano of the Cape Verde Archipelago in the eastern Atlantic Ocean. We determine H2O, S, Cl, F in glassy melt inclusions and recalculate the total (glass + shrinkage bubbles) CO2 budget by three independent methodologies. We find that the Fogo parental basanite, entrapped as melt inclusion in forsterite-rich (Fo80-85) olivines, contains up to ~2.1 wt% CO2, 3–47 % of which is partitioned in the shrinkage bubbles. This CO2 content is among the highest ever measured in melt inclusions in OIBs. In combination with ~2 wt% H2O content, our data constrain an entrapment pressure range for the most CO2-rich melt inclusion of 648–1430 MPa, with a most conservative estimate at 773–1020 MPa. Our results therefore suggest the parental Fogo melt is stored in the lithospheric mantle at minimum depths of ~27 to ~36 km, and then injected into a vertically stacked magma ponding system. Overall, our results corroborate previous indications for a CO2-rich nature of alkaline ocean island volcanism. We propose that the Fogo basanitic melt forms by low degrees of melting (F = 0.06–0.07) of a carbonenriched mantle source, containing up to 355–414 ppm C. If global OIB melts are dominantly as carbon-rich as our Fogo results suggest, then OIB volcanism may cumulatively outgas
    Description: Published
    Description: 93-111
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Keywords: Alkaline ocean islands ; Intraplate volcanism ; Fogo volcano ; Melt inclusions ; Cape Verde
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 84
    Publication Date: 2024-02-09
    Description: between Elba Island and Monte Argentario promontory, was performed to reappraise the Tuscan shelf tectonic evolution. Despite the almost flat geometry of the seafloor, seismic profiles show a corrugated morphology of the pre-neogenic deformed acoustic basement, organized in structural highs and narrow, mostly N-S and NNW-SSE basins. We identified an intimate relationship between the thrust-related structural highs and the position of the basins, principally located at the forelimb and backlimb of major antiforms, a legacy of a primarily Miocene compressional stage. During the middle Miocene, the Tyrrhenian Sea opening set up, and the extensional front migrated from west to east, progressively activating and deactivating the observed high-angle faults, blandly controlling the sedimentation within the basins. After the late Messinian, a regional collapse stage led to the deepening and widening of the basins. A progressive deactivation of all the normal faults is recorded from the lower Pliocene. After the Late Pliocene/early Pleistocene, the area turned into a passive and widespread sinking stage without any frank tectonic activity. Results show that regional thrusts shaped the main architecture of the Tuscan Shelf shallow crust, while the neogenic depocenters started to develop as thrust-top basins along the flanks of the inherited antiforms. Intriguingly and partially in contrast with previous works, no evidence of lowangle normal fault was observed. We propose an innovative model that poses new questions on the crustal-scale mechanisms responsible for Tyrrhenian extensional process-related features, also establishing a new and unique starting point for fully unraveling the tectonic evolution of this portion of central Italy's offshore domain.
    Description: Published
    Description: 230211
    Description: OST1 Alla ricerca dei Motori Geodinamici
    Description: JCR Journal
    Keywords: Tyrrhenian Sea ; Tuscan shelf ; Neogenic basins ; Extensional tectonics ; Inherited structures
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 85
    Publication Date: 2024-02-13
    Description: The availability of silicon (Si) in the ocean plays an important role in regulating biogeochemical and ecological processes. The Si budget of the Arctic Ocean appears balanced, with inputs equivalent to outputs, though it is unclear how a changing climate might aggravate this balance. In this study, we focus on Si cycling in Arctic coastal areas and continental shelf sediments to better constrain the Arctic Ocean Si budget. We provide the first estimate of amorphous Si (ASi) loading from erosion of coastal Yedoma deposits (30–90 Gmol yr−1), demonstrating comparable rates to particulate Si loading from rivers (10–90 Gmol yr−1). We found a positive relationship between surface sediment ASi and organic matter content on continental shelves. Combining these values with published Arctic shelf sediment properties and burial rates we estimate 70 Gmol Si yr−1 is buried on Arctic continental shelves, equivalent to 4.5% of all Si inputs to the Arctic Ocean. Sediment dissolved Si fluxes increased with distance from river mouths along cruise transects of shelf regions influenced by major rivers in the Laptev and East Siberian seas. On an annual basis, we estimate that Arctic shelf sediments recycle approximately up to twice as much DSi (680 Gmol Si) as is loaded from rivers (340–500 Gmol Si).
    Repository Name: EPIC Alfred Wegener Institut
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  • 86
    facet.materialart.
    Unknown
    American Geophysical Union (AGU)
    In:  EPIC3Global Biogeochemical Cycles, American Geophysical Union (AGU), 38(1), ISSN: 0886-6236
    Publication Date: 2024-02-13
    Description: The coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). In this second phase of the Regional Carbon Cycle Assessment and Processes (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4 using an ensemble of global gap-filled observation-based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2 in both observational products and models, but the magnitude of the median net global coastal uptake is ∼60% larger in models (−0.72 vs. −0.44 PgC year−1, 1998–2018, coastal ocean extending to 300 km offshore or 1,000 m isobath with area of 77 million km2). We attribute most of this model-product difference to the seasonality in sea surface CO2 partial pressure at mid- and high-latitudes, where models simulate stronger winter CO2 uptake. The coastal ocean CO2 sink has increased in the past decades but the available time-resolving observation-based products and models show large discrepancies in the magnitude of this increase. The global coastal ocean is a major source of N2O (+0.70 PgCO2-e year−1 in observational product and +0.54 PgCO2-e year−1 in model median) and CH4 (+0.21 PgCO2-e year−1 in observational product), which offsets a substantial proportion of the coastal CO2 uptake in the net radiative balance (30%–60% in CO2-equivalents), highlighting the importance of considering the three greenhouse gases when examining the influence of the coastal ocean on climate.
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  • 87
    Publication Date: 2024-02-13
    Description: In this work, we analyze 12 meteorological events that occurred in the Mediterranean Sea during the period November 2011-November 2021 from a seismic point of view. In particular, we consider 8 Medicanes and 4 more common storms. Each of these events, in spite of the marked differences between them, caused heavy rainfall, strong wind gusts and violent storm surge with significant wave heights usually 〉3 m. We deal with the relationships between these meteorological events and the features of microseism (the most continuous and widespread seismic signal on Earth) in terms of spectral content, space-time variation of the amplitude and source locations tracked employing two different methods (amplitude decay-based grid search and array techniques). By comparing the positions of the microseism sources with the areas of significant storm surges, we observe that the microseism locations align with the actual locations of the storm surges for 10 out of 12 events analyzed (two Medicanes present very low intensity in terms of meteorological parameters and the microseism amplitude does not show significant variations during these two events). We also perform two analyses that allowed us to obtain both the seismic signature of these events, by using a method that exploits the coherence of continuous seismic noise, and their strength from a seismic point of view, called Microseism Reduced Amplitude. In addition, by integrating the results obtained from these two methods, we are able to "seismically" distinguish Medicanes and common storms. Consequently, we demonstrate the possibility of creating a novel monitoring system for Mediterranean meteorological events by incorporating microseism information alongside with other commonly employed techniques for studying meteorological phenomena. The integration of microseism with the data provided by routinely used techniques in sea state monitoring (e.g., wave buoy and HF radar) has the potential to offer valuable insights into the examination of historical extreme weather events within the context of climate change.
    Description: Published
    Description: 169989
    Description: OSA4: Ambiente marino, fascia costiera ed Oceanografia operativa
    Description: JCR Journal
    Keywords: Climate change ; Common storms ; Hindcast maps ; Medicanes ; Mediterranean Sea ; Microseism ; Monitoring sea state ; Wave buoys
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 88
    Publication Date: 2024-02-27
    Description: Significant progress in permafrost carbon science made over the past decades include the identification of vast permafrost carbon stocks, the development of new pan‐Arctic permafrost maps, an increase in terrestrial measurement sites for CO〈jats:sub〉2〈/jats:sub〉 and methane fluxes, and important factors affecting carbon cycling, including vegetation changes, periods of soil freezing and thawing, wildfire, and other disturbance events. Process‐based modeling studies now include key elements of permafrost carbon cycling and advances in statistical modeling and inverse modeling enhance understanding of permafrost region C budgets. By combining existing data syntheses and model outputs, the permafrost region is likely a wetland methane source and small terrestrial ecosystem CO〈jats:sub〉2〈/jats:sub〉 sink with lower net CO〈jats:sub〉2〈/jats:sub〉 uptake toward higher latitudes, excluding wildfire emissions. For 2002–2014, the strongest CO〈jats:sub〉2〈/jats:sub〉 sink was located in western Canada (median: −52 g C m〈jats:sup〉−2〈/jats:sup〉 y〈jats:sup〉−1〈/jats:sup〉) and smallest sinks in Alaska, Canadian tundra, and Siberian tundra (medians: −5 to −9 g C m〈jats:sup〉−2〈/jats:sup〉 y〈jats:sup〉−1〈/jats:sup〉). Eurasian regions had the largest median wetland methane fluxes (16–18 g CH〈jats:sub〉4〈/jats:sub〉 m〈jats:sup〉−2〈/jats:sup〉 y〈jats:sup〉−1〈/jats:sup〉). Quantifying the regional scale carbon balance remains challenging because of high spatial and temporal variability and relatively low density of observations. More accurate permafrost region carbon fluxes require: (a) the development of better maps characterizing wetlands and dynamics of vegetation and disturbances, including abrupt permafrost thaw; (b) the establishment of new year‐round CO〈jats:sub〉2〈/jats:sub〉 and methane flux sites in underrepresented areas; and (c) improved models that better represent important permafrost carbon cycle dynamics, including non‐growing season emissions and disturbance effects.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 89
    Publication Date: 2024-02-27
    Description: Volcanism in continental rifts is generally observed to shift over time from the inside of the basin to its flanks and vice versa, but the controls on these switches are still unclear. Here we use numerical simulations of dike propagation to test the hypothesis that the spatio-temporal evolution of rift volcanism is controlled by the crustal stresses produced during the development of the rift basin. We find that the progressive deepening of a rift rotates the direction of the principal stresses under the basin, deflecting ascending dikes. This causes an early shift of volcanism from the inside of the graben to its flanks. The intensification of this stress pattern, due to further deepening of the basin, promotes the formation of lower crustal sill-like intrusions that can stack under the rift, shallowing the depth at which dikes nucleate, eventually causing a late stage of in-rift axial volcanism. Given the agreement between our model results and observations, we conclude that the temporal shifts in the location of rift volcanism are controlled to first order by the elastic stresses developing in the crust as the rift matures. We thereby suggest that geodynamic models should account for elasticity and the redistribution of surface loads in order to effectively reproduce rift-related magmatism.
    Description: Published
    Description: 118593
    Description: OSV1: Verso la previsione dei fenomeni vulcanici pericolosi
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 90
    Publication Date: 2024-02-28
    Description: The stomach content of 60 krill specimens from the Southern Ocean were analyzed for the presence of micro-plastic (MP), by testing different sample volumes, extraction approaches, and applying hyperspectral imaging Fourier-transform infrared spectroscopy (μFTIR). Strict quality control was applied on the generated results. A high load of residual materials in pooled samples hampered the analysis and avoided a reliable determination of putative MP particles. Individual krill stomachs displayed reliable results, however, only after re-treating the samples with hydrogen peroxide. Before this treatment, lipid rich residues of krill resulted in false assignments of polymer categories and hence, false high MP particle numbers. Finally, MP was identified in 4 stomachs out of 60, with only one MP particle per stomach. Our study highlights the importance of strict quality control to verify results before coming to a final decision on MP contamination in the environment to aid the establishment of suitable internationally standardized protocols for sampling and analysis of MP in organisms including their habitats in Southern Ocean and worldwide.
    Repository Name: EPIC Alfred Wegener Institut
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  • 91
    facet.materialart.
    Unknown
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Solid Earth, American Geophysical Union (AGU), 129(3), ISSN: 2169-9313
    Publication Date: 2024-03-04
    Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Extensive investigation of continental rift systems has been fundamental for advancing the understanding of extensional tectonics and modes of formation of new ocean basins. However, current rift classification schemes do not account for conjugate end members formed by Large Igneous Province crust, referring to thick mafic crust, sometimes including continental fragments. Here, we investigate the rifting of William's Ridge (Kerguelen Plateau) and Broken Ridge, components of the Kerguelen Large Igneous Province now situated in the Southeast Indian Ocean, and incorporate these end members into the deformation migration concept for rifted margins. We use multichannel seismic reflection profiles and data from scientific drill cores acquired on both conjugate margins to propose, for the first time, a combined tectono‐stratigraphic framework. We interpret seismic patterns, tectonic features, and magnetic anomaly picks to determine an across‐strike structural domain classification. This interpretation considers the rift system overall to be “magma‐poor” despite being located proximal to the Kerguelen plume but suggests that syn‐rift interaction between the Kerguelen mantle plume and the lithospheric structure of William's Ridge and Broken Ridge has controlled the along‐strike segmentation of both conjugates. We integrate seismic reflection and bathymetric data to test the hypothesis of predominantly transform motion, between the Australian and Antarctic plates, in Late Cretaceous and Paleogene time.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 92
    facet.materialart.
    Unknown
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Solid Earth, American Geophysical Union (AGU), 129(3), ISSN: 2169-9313
    Publication Date: 2024-03-04
    Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Extensive investigation of continental rift systems has been fundamental for advancing the understanding of extensional tectonics and modes of formation of new ocean basins. However, current rift classification schemes do not account for conjugate end members formed by Large Igneous Province crust, referring to thick mafic crust, sometimes including continental fragments. Here, we investigate the rifting of William's Ridge (Kerguelen Plateau) and Broken Ridge, components of the Kerguelen Large Igneous Province now situated in the Southeast Indian Ocean, and incorporate these end members into the deformation migration concept for rifted margins. We use multichannel seismic reflection profiles and data from scientific drill cores acquired on both conjugate margins to propose, for the first time, a combined tectono‐stratigraphic framework. We interpret seismic patterns, tectonic features, and magnetic anomaly picks to determine an across‐strike structural domain classification. This interpretation considers the rift system overall to be “magma‐poor” despite being located proximal to the Kerguelen plume but suggests that syn‐rift interaction between the Kerguelen mantle plume and the lithospheric structure of William's Ridge and Broken Ridge has controlled the along‐strike segmentation of both conjugates. We integrate seismic reflection and bathymetric data to test the hypothesis of predominantly transform motion, between the Australian and Antarctic plates, in Late Cretaceous and Paleogene time.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 93
    facet.materialart.
    Unknown
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Solid Earth, American Geophysical Union (AGU), 129(3), ISSN: 2169-9313
    Publication Date: 2024-03-04
    Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Extensive investigation of continental rift systems has been fundamental for advancing the understanding of extensional tectonics and modes of formation of new ocean basins. However, current rift classification schemes do not account for conjugate end members formed by Large Igneous Province crust, referring to thick mafic crust, sometimes including continental fragments. Here, we investigate the rifting of William's Ridge (Kerguelen Plateau) and Broken Ridge, components of the Kerguelen Large Igneous Province now situated in the Southeast Indian Ocean, and incorporate these end members into the deformation migration concept for rifted margins. We use multichannel seismic reflection profiles and data from scientific drill cores acquired on both conjugate margins to propose, for the first time, a combined tectono‐stratigraphic framework. We interpret seismic patterns, tectonic features, and magnetic anomaly picks to determine an across‐strike structural domain classification. This interpretation considers the rift system overall to be “magma‐poor” despite being located proximal to the Kerguelen plume but suggests that syn‐rift interaction between the Kerguelen mantle plume and the lithospheric structure of William's Ridge and Broken Ridge has controlled the along‐strike segmentation of both conjugates. We integrate seismic reflection and bathymetric data to test the hypothesis of predominantly transform motion, between the Australian and Antarctic plates, in Late Cretaceous and Paleogene time.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 94
    facet.materialart.
    Unknown
    American Geophysical Union (AGU)
    In:  EPIC3Geochemistry Geophysics Geosystems, American Geophysical Union (AGU), 25(1), ISSN: 1525-2027
    Publication Date: 2024-03-04
    Description: Mineral dust accumulated on the ocean floor is an important archive for reconstructing past atmospheric circulation changes and climatological conditions in the source areas. Dust emitted from Southern Hemisphere dust sources is widely deposited over the oceans. However, there are few records of dust deposition over the open ocean, and a large need for extended geographical coverage exists. We present a large data set (134 surface sediment samples) of Late Holocene dust deposition from seafloor surface sediments covering the entire South Atlantic Ocean. Polymodal grain-size distributions of the lithogenic fraction indicate that the sediments are composed of multiple sediment components. By using end-member modeling, we attempt to disentangle the dust signal from non-aeolian sediments. Combined with 230Th-normalized lithogenic fluxes, we quantified the specific deposition fluxes for mineral dust, crrent-sorted sediments and ice-rafted debris (IRD). Although the method could not completely separate the different components in every region, it shows that dust deposition off the most prominent dust source for the South Atlantic Ocean—southern South America—amounts up to approximately 0.7 g cm−2 Kyr−1 and decreases downwind. Bottom-current-sorted sediments and IRD are mostly concentrated around the continental margins. The ratio of the coarse to fine dust end members reveals input from north African dust sources to the South Atlantic. The majority of the observations are in good agreement with new model simulations. This extensive and relevant data set of dust grain size and deposition fluxes to the South Atlantic could be used to calibrate and validate further model simulations.
    Repository Name: EPIC Alfred Wegener Institut
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  • 95
    facet.materialart.
    Unknown
    American Geophysical Union (AGU)
    In:  EPIC3Journal of Geophysical Research: Solid Earth, American Geophysical Union (AGU), 129(3), ISSN: 2169-9313
    Publication Date: 2024-03-04
    Description: 〈jats:title〉Abstract〈/jats:title〉〈jats:p〉Extensive investigation of continental rift systems has been fundamental for advancing the understanding of extensional tectonics and modes of formation of new ocean basins. However, current rift classification schemes do not account for conjugate end members formed by Large Igneous Province crust, referring to thick mafic crust, sometimes including continental fragments. Here, we investigate the rifting of William's Ridge (Kerguelen Plateau) and Broken Ridge, components of the Kerguelen Large Igneous Province now situated in the Southeast Indian Ocean, and incorporate these end members into the deformation migration concept for rifted margins. We use multichannel seismic reflection profiles and data from scientific drill cores acquired on both conjugate margins to propose, for the first time, a combined tectono‐stratigraphic framework. We interpret seismic patterns, tectonic features, and magnetic anomaly picks to determine an across‐strike structural domain classification. This interpretation considers the rift system overall to be “magma‐poor” despite being located proximal to the Kerguelen plume but suggests that syn‐rift interaction between the Kerguelen mantle plume and the lithospheric structure of William's Ridge and Broken Ridge has controlled the along‐strike segmentation of both conjugates. We integrate seismic reflection and bathymetric data to test the hypothesis of predominantly transform motion, between the Australian and Antarctic plates, in Late Cretaceous and Paleogene time.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 96
    Publication Date: 2024-03-19
    Description: The Qinghai-Tibet Plateau (QTP) is characterized by a vast number of frozen and unfrozen freshwater reservoirs, which is why it is also called “the third pole” of the Earth or “Asian Water Tower”. We analyzed testate amoeba (TA) biodiversity and corresponding protozoic biosilicification in lake sediments of the QTP in relation to environmental properties (freshwater conditions, elevation, and climate). As TA are known as excellent bio-indicators, our results allowed us to derive conclusions about the influence of climate warming on TA communities and microbial biogeochemical silicon (Si) cycling. We found a total of 113 TA taxa including some rare and one unknown species in the analyzed lake sediments of the QTP highlighting the potential of this remote region for TA biodiversity. 〉1/3 of the identified TA taxa were relatively small (〈30 μm) reflecting the relatively harsh environmental conditions in the examined lakes. TA communities were strongly affected by physico-chemical properties of the lakes, especially water temperature and pH, but also elevation and climate conditions (temperature, precipitation). Our study reveals climate-related changes in TA biodiversity with consequences for protozoic biosilicification. As the warming trend in the QTP is two to three times faster compared to the global average, our results provide not only deeper insights into the relations between TA biodiversity and environmental properties, but also predictions of future developments in other regions of the world. Moreover, our results provide fundamental data for paleolimnological reconstructions. Thus, examining the QTP is helpful to understand microbial biogeochemical Si cycling in the past, present, and future.
    Repository Name: EPIC Alfred Wegener Institut
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  • 97
    Publication Date: 2024-03-13
    Description: Crystal-chemical variations of pyroxene (px) and plagioclase (plg) have been analysed by X-ray electron-microprobe (EPMA) mapping to quantify their actual chemical dispersions. These phases were experimentally crystallised from a basaltic liquid (B100, MORB from Iceland) at cooling rates of 1, 7, 60 and 180 °C/h from 1300 °C down to 800 °C. Experiments were run at ambient conditions applying defined temperature paths mirroring characteristic cooling rates from innermost to outermost portions of metre- to centimetre-thick lavas, dikes and bombs emplaced under submarine to subaerial conditions. As the cooling rate increases from 1 to 180 °C/h, the run-products become progressively enriched in pyroxene and depleted in plagioclase, while spinel is invariably low (few area%) and glass is significant only at 180 °C/h. An increase of cooling rate generally leads to enrichment of Al2O3 and depletion of MgO in px, while the opposite behaviour is observed for plg; these trends are mirrored by calculated cations (apfu: atom per formula unit) and components. Average variations as a function of cooling rate are similar to those already observed through classical analysis performed by single point EPMA. However, the actual chemical distributions of CaO versus MgO, Al2O3 and FeOtot oxides unveil the presence of a wider range in pyroxene chemistry. In particular, one px (px-1, CaO-rich, diopsidic type) is present at all the applied cooling rates; a very low CaO-px (px-2, pigeonite or orthopyroxene type) is detected at 1 °C/h; and, finally, once more population of px (px-3, CaO-poor diopsidic type) appears at 60 and 180 °C/h. By contrast, plg analyses yield invariably identical compositions. Textural variations as a function of cooling rate and geothermometric estimations indicate that px-1 crystallised at high-T (or low ΔT), while plg mainly grew in the residual melt produced by the saturation of px. If only textures were evaluated, this order of segregation would like remain unrecognised since px at low cooling rates is smaller than plg. The abundance of phases, their crystal-chemical features, and their order of segregation can be regarded through a theoretical framework of a time-temperature-transformation (TTT) diagram. The most significant chemical variations are displayed by MgO and Al2O3 for both px and plg, which faithfully capture the evolution of cooling conditions. The chemical compositions of px-1 is close to the thermodynamic equilibrium only at 1 °C/h. As the cooling rates increase, the px chemistry indicates disequilibrium conditions. Finally, this study shows that as ΔT/Δt increases, the most abundant px (px-1) and plg are forced towards compositions that become progressively closer to those of the parental liquid.
    Description: Published
    Description: 121752
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 98
    Publication Date: 2024-03-13
    Description: We present kinetic partitioning data for trace cations measured in zoned clinopyroxene crystals obtained from a variably cooled and decompressed olivine basalt erupted at Mt. Etna volcano in Italy. Supersaturation effects and compositional heterogeneities at the interface melt lead to the development of sector zoning, concentric zoning, and patchy zoning in clinopyroxene crystals. Apparent partition coefficients between compositionally different growth layers and adjacent melts (Di) for isovalent groups of trace elements are tested for internal consistency on the thermodynamic basis of lattice strain (ΔGstrain) and electrostatic (ΔGelec) energies of substitutions. The excess energy of partitioning (ΔGpartitioning) for trace cations in zoned crystals accounts for a kinetic incorporation control leading to large enthalpic effects through distortion of the lattice and changes in the electrostatic forces. ΔGpartitioning depends upon the complementary relationship between ΔGstrain and ΔGelec, which is the most appropriate thermodynamic description for the accommodation of rare earth elements and high field strength elements in the lattice site of zoned crystals. Polyhedral sectors, skeletal forms, and overgrowth zones have Di values settled by the number of charge-balanced and -imbalanced configurations taking place in the lattice site as a function of aluminium in tetrahedral coordination, and crystal structural changes produced by heterovalent cation substitutions. In an energetically unstable macroscopic system ruled by cooling and decompression, thermodynamic requirements for the crystallochemical control of Di encompass the attainment of local equilibrium at the crystal-melt interface via the establishment of small-volume reaction kinetics. The requisite of local interface equilibrium is however susceptible to the anisotropic growth velocity of each specific clinopyroxene surface, thereby giving reason to different energetic properties of the crystallographic site. This axiomatic control requires that transition metal cations partition also in consideration of electronic effects related to the crystal field stabilization energy. The overriding implication is that Di values for trace cations having different size, charge, and electronic configuration serve as sensitive probes of the different crystal growth mechanisms, surface incorporation sites, and arrangements of atoms at the lattice-scale. In this perspective, fractional crystallization modeling of 2011–2013 bulk rock data from lava fountains indicates that the compositional evolution of magmas erupted at Mt. Etna cannot be described by a unique equilibrium value of Di for a given clinopyroxene-melt interface. The leverage of interface kinetics is distinctively dominant along the subvolcanic plumbing system, thereby requiring that values of Di differ for structurally and compositionally distinct zones in clinopyroxene phenocrysts. To successfully interpret the trace element signature of Etnean magmas, the archetypal constancy of partition coefficient at bulk thermodynamic equilibrium must be in some measure reappraised in favor of the establishment of a local interface equilibrium upon highly dynamic crystallization and growth conditions.
    Description: Published
    Description: 40-66
    Description: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 99
    Publication Date: 2024-03-13
    Description: Climate change affects human activities, including tourism across various sectors and time frames. The winter tourism industry, dependent on low temperatures, faces significant impacts. This paper reviews the implications of climate change on winter tourism, emphasising challenges for activities like skiing and snowboarding, which rely on consistent snowfall and low temperatures. As the climate changes, these once taken-for-granted conditions are no longer as commonplace. Through a comprehensive review supported by up-to-date satellite imagery, this paper presents evidence suggesting that the reliability of winter snow is decreasing, with findings revealing a progressive reduction in snow levels associated with temperature and precipitation changes in some regions. The analysis underscores the need for concerted efforts by stakeholders who must recognize the reality of diminishing snow availability and work towards understanding the specific changes in snow patterns. This should involve multi-risk and multi-instrument assessments, including ongoing satellite data monitoring to track snow cover changes. The practical implications for sports activities and the tourism industry reliant on snow involve addressing challenges by diversifying offerings. This includes developing alternative winter tourism activities less dependent on snow, such as winter hiking, nature walks, or cultural experiences.
    Description: In press
    Description: OSA2: Evoluzione climatica: effetti e loro mitigazione
    Description: JCR Journal
    Keywords: Climate change ; Adaptation ; Tourism losses ; Winter sport ; Multi-date satellite imagery ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 100
    Publication Date: 2024-03-13
    Description: This article describes a dataset of acceleration signals acquired from a low-cost Wireless Sensor Network (WSN) during seismic events that occurred in Central Italy. The WSN consists of 5 low-cost sensor nodes, each embedding an ADXL355 tri-axial MEMS accelerometer with a fixed sampling frequency of 250 Hz. The data was acquired from February 2023 to the end of June 2023. During this period, several earthquake sequences affected the area where the sensor network was installed. Continuous data was acquired from the WSN and then trimmed around the origin time of seismic events that occurred near the installation site, close to the city of Pollenza (MC), Italy. A total of 67 events were selected, whose data is available at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) Seismology data center. The traces acquired from the WSN were then manually annotated by analysts from INGV. Annotations include picking time for P and S phases, when distinguishable from the background noise, alongside an associated uncertainty level for the manual annotations. The resulting dataset consists of 328 3 × 25,001 arrays, each associated with its metadata. The metadata includes event data (hypocenter position, origin time, magnitude, magnitude type, etc.), trace-related data (mean, median, maximum, and minimum amplitudes, manual picks, and picks uncertainty), and sensor-specific data (sensor name, sensitivity, and orientation). Furthermore, a small dataset consisting of non-seismic traces is included, with the goal of providing records of noise-only traces, relative to both electronic and environmental/anthropic noise sources. The dataset holds potential for training and developing Machine Learning or signal processing algorithms for seismic data with low signal-to-noise ratios. Additionally, it is valuable for research about earthquakes, structural health monitoring, and MEMS accelerometer performance in civil and seismic engineering applications.
    Description: Published
    Description: 110174
    Description: OST5 Verso un nuovo Monitoraggio
    Description: JCR Journal
    Keywords: Earthquake early warning; Internet of things; MEMS accelerometers; Structural health monitoring; Wireless sensor network ; 05.04. Instrumentation and techniques of general interest ; 05.02. Data dissemination ; 04.06. Seismology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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