ALBERT

Description: The sustainable management of water resources is required to avoid water scarcity becoming widespread. This article explores the potential application of a social-ecological framework, used predominantly in the fields of ecology and conservation, as a tool to improve the sustainability and resilience of water resources. The "red-loop green-loop" (RL-GL) model has previously been used to map both sustainable and unsustainable social-ecological feedbacks between ecosystems and their communities in countries such as Sweden and Jamaica. In this article, we demonstrate the novel application of the RL-GL framework to water resources management using the 2017/18 Cape Town water crisis. We used the framework to analyse the social-ecological dynamics of pre-crisis and planned contingency scenarios. We found that the water resources management system was almost solely reliant on a single, non-ecosystem form of infrastructure, the provincial dam system. As prolonged drought impacted this key water resource, resilience to resource collapse was shown to be low and a missing feedback between the water resource and the Cape Town community was highlighted. The collapse of water resources ("Day Zero") was averted through a combination of government and community group led measures, incorporating both local ecosystem (green-loop) and non-local ecosystem (red-loop) forms of water resource management, and increased rainfall returning to the area. Additional disaster management plans proposed by the municipality included the tighter integration of red and green-loop water management approaches, which acted to foster a stronger connection between the Cape Town community and their water resources. We advocate the wider development and application of the RL-GL model, theoretically and empirically, to investigate missing feedbacks between water resources and their communities.

Description: Despite an increasing understanding of the issue of marine pollution, humanity continues on a largely unsustainable trajectory. This study aimed to identify and classify the range of scientific studies and interventions to address coastal and marine pollution. We reviewed 2417 scientific papers published between 2000 and 2018, 741 of which we analysed in depth. To classify pollution interventions, we applied the systems-oriented concept of leverage points, which focuses on places to intervene in complex systems to bring about systemic change. We found that pollution is largely studied as a technical problem and fewer studies engage with pollution as a systemic social-ecological issue. While recognising the importance of technical solutions, we highlight the need to focus on under-researched areas pertaining to the deeper drivers of pollution (e.g. institutions, values) which are needed to fundamentally alter system trajectories.

Description: It is important to understand the historical precedents of current situations to be able to anticipate where the current global environmental and climatic change may lead. Geo-historical data provide information beyond the limitations of instrumental data. This study aims to reconstruct components of the palaeoclimatic and palaeoenvironmental history of the Beagle Channel (BC) during the Late Holocene by using Ameghinomya antiqua shells. We use fossil and modern shells in a comparative analysis through a multiproxy approach, i.e., shell morphometrics, shell growth, and stable oxygen isotope ratios. A holistic analysis of all the proxies indicates that higher productivity occurred around 3542 yr B.P. in the BC, evidenced by more significant growth, size, and longevity in fossil specimens. In addition, smaller ligaments, cardinal teeth, and the pallial sinus in fossil specimens indicate a low-energy environment typical of a marine archipelago. Lastly, palaeotemperatures are estimated to be warmer than today, although the intensity may be overestimated due to the freshwater inflow that would change the salinity of the BC waters. Further analysis in Late-Holocene shells is essential for a more detailed environmental reconstruction around the southern tip of South America.

Description: Harmful algal blooms (HAB) are recurrent phenomena in northern Europe along the coasts of the Baltic Sea, Kattegat-Skagerrak, eastern North Sea, Norwegian Sea and the Barents Sea. These HABs have caused occasional massive losses for the aquaculture industry and have chronically affected socioeconomic interests in several ways. This status review gives an overview of historical HAB events and summarises reports to the Harmful Algae Event Database from 1986 to the end of year 2019 and observations made in long term monitoring programmes of potentially harmful phytoplankton and of phycotoxins in bivalve shellfish. Major HAB taxa causing fish mortalities in the region include blooms of the prymnesiophyte Chrysochromulina leadbeateri in northern Norway in 1991 and 2019, resulting in huge economic losses for fish farmers. A bloom of the prymesiophyte Prymnesium polylepis (syn. Chrysochromulina polylepis) in the Kattegat-Skagerrak in 1988 was ecosystem disruptive. Blooms of the prymnesiophyte Phaeocystis spp. have caused accumulations of foam on beaches in the southwestern North Sea and Wadden Sea coasts and shellfish mortality has been linked to their occurrence. Mortality of shellfish linked to HAB events has been observed in estuarine waters associated with influx of water from the southern North Sea. The first bloom of the dictyochophyte genus Pseudochattonella was observed in 1998, and since then such blooms have been observed in high cell densities in spring causing fish mortalities some years. Dinoflagellates, primarily Dinophysis spp., intermittently yield concentrations of Diarrhetic Shellfish Toxins (DST) in blue mussels, Mytilus edulis, above regulatory limits along the coasts of Norway, Denmark and the Swedish west coast. On average, DST levels in shellfish have decreased along the Swedish and Norwegian Skagerrak coasts since approximately 2006, coinciding with a decrease in the cell abundance of D. acuta. Among dinoflagellates, Alexandrium species are the major source of Paralytic Shellfish Toxins (PST) in the region. PST concentrations above regulatory levels were rare in the Skagerrak-Kattegat during the three decadal review period, but frequent and often abundant findings of Alexandrium resting cysts in surface sediments indicate a high potential risk for blooms. PST levels often above regulatory limits along the west coast of Norway are associated with A. catenella (ribotype Group 1) as the main toxin producer. Other Alexandrium species, such as A. ostenfeldii and A. minutum, are capable of producing PST among some populations but are usually not associated with PSP events in the region. The cell abundance of A. pseudogonyaulax, a producer of the ichthyotoxin goniodomin (GD),has increased in the Skagerrak-Kattegat since 2010, and may constitute an emerging threat. The dinoflagellate Azadinium spp. have been unequivocally linked to the presence of azaspiracid toxins (AZT) responsible for Azaspiracid Shellfish Poisoning (AZP) in northern Europe. These toxins were detected in bivalve shellfish at concentrations above regulatory limits for the first time in Norway in blue mussels in 2005 and in Sweden in blue mussels and oysters (Ostrea edulis and Crassostrea gigas) in 2018. Certain members of the diatom genus Pseudonitzschia produce the neurotoxin domoic acid and analogs known as Amnesic Shellfish Toxins (AST). Blooms of Pseudo-nitzschia were common in the North Sea and the Skagerrak-Kattegat, but levels of AST in bivalve shellfish were rarely above regulatory limits during the review period. Summer cyanobacteria blooms in the Baltic Sea are a concern mainly for tourism by causing massive fouling of bathing water and beaches. Some of the cyanobacteria produce toxins, e.g. Nodularia spumigena producer of nodularin, which may be a human health problem and cause occasional dog mortalities. Coastal and shelf sea regions in northern Europe provide a key supply of seafood, socioeconomic well-being and ecosystem services. Increasing anthropogenic influence and climate change create environmental stressors causing shifts in the biogeography and intensity of HABs. Continued monitoring of HAB and phycotoxins and the operation of historical databases such as HAEDAT provide not only an ongoing status report but also provide a way to interpret causes and mechanisms of HABs.

Description: The IOC-ICES-PICES Harmful Algal Event Database (HAEDAT) was used to describe the diversity and spatiotemporal distribution of harmful algal events along the Atlantic margin of Europe from 1987 - 2018. The majority of events recorded are caused by Diarrhetic Shellfish Toxins (DSTs). These events are recorded annually over a wide geographic area from southern Spain to northern Scotland and Iceland, and are responsible for annual closures of many shellfish harvesting areas. The dominant causative dinoflagellates, members of the morphospecies ‘Dinophysis acuminata complex’ and D. acuta, are common in the waters of the majority of countries affected. There are regional differences in the causative species associated with PST events; the coasts of Spain and Portugal with the dinoflagellates Alexandrium minutum and Gymnodinium catenatum, north west France/south west England/south Ireland with A. minutum, and Scotland/Faroe Islands/Iceland with A. catenella. This can influence the duration and spatial scale of PST events as well as the toxicity of shellfish. The diatom Pseudo-nitzschia australis is the most widespread Domoic Acid (DA) producer, with records coming from Spain, Portugal, France, Ireland and the UK. Amnesic Shellfish Toxins (ASTs) have caused prolonged closures for the scallop fishing industry due to the slow depuration rate of DA. Amendments to EU shellfish hygiene regulations introduced between 2002 and 2005 facilitated end-product testing and sale of adductor muscle. This reduced the impact of ASTs on the scallop fishing industry and thus the number of recorded HAEDAT events. Azaspiracids (AZAs) are the most recent toxin group responsible for events to be characterised in the ICES area. Events associated with AZAs have a discrete distribution with the majority recorded along the west coast of Ireland. Ciguatera Poisoning (CP) has been an emerging issue in the Canary Islands and Madeira since 2004. The majority of aquaculture and wild fish mortality events are associated with blooms of the dinoflagellate Karenia mikimotoi and raphidophyte Heterosigma akashiwo. Such fish killing events occur infrequently yet can cause significant mortalities. Interannual variability was observed in the annual number of HAEDAT areas with events associated with individual shellfish toxin groups. HABs represent a continued risk for the aquaculture industry along the Atlantic margin of Europe and along the Atlantic margin of Europe and should be accounted for when considering expansion of the industry or operational shifts to offshore areas.

Description: 42 pages

Description: In this study, we propose an analysis of the earthquake clusters that occurred in North-Eastern Italy and western Slovenia from 1977 to today. Given a mainshock generating alarm in the population, we are interested in forecasting if a similar magnitude earthquake will follow. We classify the earthquake clusters associated with mainshocks of magnitude Mm into two classes: if the strongest aftershock has a magnitude 〉=Mm-1 (swarms or large aftershock seismic sequences) as type A, otherwise (smaller aftershocks seismic sequences) as type B. A large aftershock following a main shock can cause significant damages to already weakened buildings and infrastructures, so a timely advisory information to the civil protection is of great interest for effective decision-making. For the first time, we applied to a new catalogue a pattern recognition algorithm for cluster type forecasting that we developed for all Italy (Gentili and Di Giovambattista, 2017). Thanks to the lower completeness magnitude of the local OGS catalogue, compared to the national one, and to a new version of the algorithm, we were able to lower the threshold of the clusters mainshocks magnitude from 4.5 to 3.7. The method has been validated by rigorous statistical tests. We tested the algorithm on the 1976 highly destructive earthquake cluster (mainshock magnitude 6.5 - the strongest in the last 80 years in the region) and we retrospectively forecasted it as an A cluster. Successful results were obtained also on other three smaller earthquake clusters in 2019.

Description: Published

Description: 106483

Description: 4T. Sismicità dell'Italia

Description: 6T. Studi di pericolosità sismica e da maremoto

Description: JCR Journal

Description: The knowledge of the secular variation of the geomagnetic field at different time scales is important to determine the mechanisms that maintain the geomagnetic field and can help to establish constraints in dynamo theories. We have focused our study on the secular variation at millennial and centennial time scale searching for characteristic periods during the last 10 kyr. The frequency study was performed using four recent updated global paleomagnetic field reconstructions (SHA.DIF.14k, CALS10k.2, BIGMUDI4k and SHAWQ2k) by applying three techniques commonly used in signal analysis: the Fourier transform, the Empirical Mode Decomposition, and the wavelet analysis. Short-term variability of the geomagnetic field energy shows recurrent periods of around 2000, 1000–1400, and 600–800 and 250–400 years. The characteristic time around 600–800 years is well determined in all paleomagnetic reconstructions and it is mostly related to the axial dipole and axial octupole terms, but also observable in the equatorial dipole. In addition to this period, longer characteristic times of around 1000–1400 years are found particularly in the equatorial dipole and quadrupole terms in SHA.DIF.14k, CALS10k.2 and BIGMUDI4k while the 2000 year period is only well determined in the total geomagnetic field energy of SHA.DIF.14k and CALS10k.2. The most detailed paleoreconstructions for younger times also detect shortest characteristic times of around 250–400 years. The long-term variation of the geomagnetic energy is only observable in the axial dipole. A characteristic period of around 7000 years in both SHA.DIF.14k and CALS10k.2 has been found. This long period is related to two decays in the dipole field and a period of increasing intensity. The oldest decay took place between 7000 BCE and 4500 BCE and the present decay that started around 100 BCE. We have modeled the 4500 BCE up to present variation as a combination of a continuous decay, representing the diffusion term of the geomagnetic field, and one pulse that reinforces the strength of the field. Results show a characteristic diffusion time of around 11,000–15,000 years, which is compatible with the diffusion times of the dipole field used in geodynamo theories.

Description: Published

Description: 106656

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: The Larderello-Travale Geothermal Field in South-West Tuscany (Italy) is the oldest and among the most pro- ductive geothermal fields in the world. A new 3D model of seismic P-wave velocity (V P ) of the upper crust beneath the geothermal field is derived by inverting a set of highly consistent travel-times from local-earth- quakes. Results document a marked correlation of V P with previously described, high-reflectivity horizons. We also determined a low velocity body (V P ∼5 km s −1 ) culminating at depths of about 7 km, with estimated vo- lume of 35–40 km 3 . Such low velocities are consistent with a granite at temperatures above 700 °C, thus in a partially-molten status.

Description: Published

Description: 101731

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Numerous sand boils were generated in the alluvial plain at the mouth of the Rio Brice˜no valley (Ecuador) during the Mw 7.8 earthquake of April 2016. The area is characterized by a series of raised marine terraces formed as a consequence of the rapid tectonic coastal uplift during the Quaternary. Boreholes and geotechnical investigations were carried during post-earthquake surveys and for the purpose of mitigating the liquefaction effects. Five lithological units were identified at a site of embankment, which represented continental-marine and transitional sedimentation since the Last Glacial Maximum. A comprehensive study of texture and petrographic composition of sand boils has been performed and compared with sandy silts and silty sands of the buried sedimentary sequence in order to identify the source levels for liquefaction. The petrographic components, in particular the low content of bioclasts and carbonate fragments of the sand boils, allow to pinpoint a source layer made up of fine-grained silty sands located between 2 and 4.5 m depth (Unit 2) whereas the deeper marine sands, richer in bioclasts, were not involved. The results support the idea that earthquake-induced liquefaction phenomena are not restricted to clean sands and well-sorted deposits, but may affect sand layers with significant amount of nonplastic silt.

Description: Published

Description: 102737

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: In Antarctica, the near-source exposures of volcanic eruption deposits are often limited as they are not well preserved in the dynamic glacial environment, thus making volcanological reconstructions of explosive eruptions extremely challenging. Fortunately, pyroclastic deposits from explosive eruptions are preserved in Southern Ocean sediments surrounding Antarctica, and the tephrostratigraphy of these sequences offers crucial volcanological information including the timing and tempo of past eruptions, their magnitude, and eruption dynamics. Here we report the results of a tephrostratigraphy and tephrochronology study focused on four sediment cores recovered from the Wood Bay area in the western Ross Sea, Antarctica. In all these sedimentary sequences, we found a well-stratified primary tephra of considerable thickness, up to 80 cm, hereafter named the Aviator Tephra (AVT). According to the characteristics of the tephra deposit and its distribution, the AVT was associated with an eruption of considerable intensity, potentially representing one of the largest Holocene eruptions recorded in Antarctica. Based on the major and trace element geochemistry and the mineral assemblage of the tephra, Mount Rittmann was identified as the source of the AVT. A Holocene age of ∼11 ka was determined by radiocarbon dating organic material within the sediments and 40Ar-39Ar dating of alkali-feldspar crystals included in the tephra. Eruption dynamics were initially dominated by hydromagmatic magma fragmentation conditions producing a sustained, relatively wet and ash-rich eruptive cloud. The eruption then evolved into a highly energetic, relatively dry magmatic Plinian eruption. The last phase was characterized by renewed efficient magma-water interaction and/or collapse of the eruptive column producing pyroclastic density currents and associated co-ignimbritic plumes. The distal tephra deposits might be linked to the widespread lag breccia layer previously identified on the rim of the Mount Rittmann caldera which share the same geochemical composition. Diatoms found in the sediments surrounding the AVT and the primary characteristics of the tephra indicate that the Wood Bay area was open sea at the time of the eruption, which is much earlier than previously thought. AVT is also an excellent tephrostratigraphic marker for the Wood Bay area, in the Ross Sea, and a useful marker for future synchronization of continental ice and marine archives in the region.

Description: Published

Description: 106629

Description: 1V. Storia eruttiva

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: 5A. Ricerche polari e paleoclima

Description: JCR Journal

Description: Over the last decade machine learning has become increasingly popular for the analysis and characterization of volcano-seismic data. One of the requirements for the application of machine learning methods to the problem of classifying seismic time series is the availability of a training dataset; that is a suite of reference signals, with known classification used for initial validation of the machine outcome. Here, we present PICOSS (Python Interface for the Classification of Seismic Signals), a modular data-curator platform for volcano-seismic data analysis, including detection, segmentation and classification. PICOSS has exportability and standardization at its core; users can select automatic or manual workflows to select and label seismic data from a comprehensive suite of tools, including deep neural networks. The modular implementation of PICOSS includes a portable and intuitive graphical user interface to facilitate essential data labelling tasks for large-scale volcano seismic studies.

Description: Published

Description: 104531

Description: 8T. Sismologia in tempo reale

Description: JCR Journal

Description: In volcanic areas, accurate localization of earthquakes requires detailed velocity and, possibly, attenuation models, taking into account wide lithological variability and high geothermal gradients. Ischia island (Campania region, Italy) is a seismically-active volcano recently affected by a Mw 3.9 event (Casamicciola, August 21, 2017, 1 km depth). Due to the lack of a specific velocity model, the earthquakes occurred on the island were localized using the one developed for the nearby Campi Flegrei caldera. The aim of this work is the definition of a mean representative 1D shear-wave velocity (Vs) and attenuation (Q) model of the shallower crust (up to 2 km depth) of Ischia. Seismic noise array and spectral ratios techniques were applied to broad band seismic signals recorded by temporary and permanent networks updated after the August 2017 earthquake. The values of both shear-wave velocity (Vs) and quality factor (Q) are realistic, with Q values comparable with those obtained for Campi Flegrei and Stromboli volcanic areas. By taking into account stratigraphic information from deep wells and ultrasonic measurements of velocity on granite and trachytic lava samples, a geological interpretation of the resulting velocity model is provided. Such a model can have significant implications for understanding the dynamics of a volcano, mainly those leading to seismic activity.

Description: Published

Description: 106970

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: In this paper, we study the spatial distribution and temporal evolution of the postseismic deformation of the 2010–2011 Rigan earthquake sequence which occurred at the southern termination of the East Lut fault system, southeast Iran. One-year GPS measurements after the Rigan earthquake sequence reveals right-lateral postseismic displacement along the East Chahqanbar fault and left-lateral postseismic displacement along the South Chahqanbar fault. To investigate the deformation variations in time and space, InSAR time-series of COSMO-SkyMed images is applied using the Small Baseline Subset algorithm. The results confirm a clear cumulative postseismic signal increasing to 8 mm during the first five months following the first mainshock in the direction of the coseismic displacement. The cumulative postseismic displacements are well correlated with the cumulative number of the aftershocks and their associated moment release. Considering this correlation and the observation of a sharp discontinuity along the coseismic fault in the displacement map, it is concluded that the after-slip mechanism is responsible for the observed postseismic deformation in the study region. This study is the first observation of a short-term postseismic motion in eastern Iran through geodetic data in contrast with long-lasting postseismic displacements following the earthquakes that occurred around Lut block. Modeling of the postseismic displacement results in a distributed slip pattern with a maximum slip of 0.8 m on the fault plane responsible for the 2010 Rigan coseismic deformation. This indicates that the postseismic deformation on barriers remained unbroken during the mainshock.

Description: Published

Description: 228630

Description: 2T. Deformazione crostale attiva

Description: JCR Journal

Description: The MEV project is running for a long-term muography measurement at the North-East crater of the Etna Volcano, after the successful conclusion of the test phase in July 2017. Two sets of data were already acquired during 2017, during the last months of the summer, and 2018. Data analysis is currently ongoing in order to extract a two-dimensional density map of the target from the measured muon flux. But before, a major improvement on data pre-processing was required. It regards in particular the algorithm for event reconstruction and filtering and the introduction of a method to extract the telescope efficiency from data themselves. The main steps of this pre-analysis and their application to the test data set is described in this paper.

Description: Published

Description: 162052

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Preliminary interpretation of geological processes during field measurement campaigns require fast data analysis to adapt ongoing target strategies. It is the case of soil investigations where coupling geochemical and geophysical records favors a better understanding of subsurface processes. This task requires (i) statistical analysis to identify areas of interest during spatial surveys and (ii) signal processing to analyze temporal series. Here we present SoilExp, an open-source Python-based Graphical User Interface (GUI) that permits to process spatial and temporal surveys of soil gases (e.g. soil CO2 flux) combined with common physical parameters (e.g. self-potential, temperature) that are synchronously recorded on the field. SoilExp mixes innovative algorithms with the more common tools used for the analysis of both spatial surveys or temporal series. It offers the possibility to display distribution plots, maps, comparative plots, spectra and spectrograms, as well as data statistical analysis, in order to deal efficiently with datasets acquired on the field. Field measurements performed at Stromboli (Italy) supports that such software solution facilitates a quick visualization of the data output and is a powerful tool on the geochemical and geophysical analysis.

Description: Published

Description: 104553

Description: 4V. Processi pre-eruttivi

Description: 5V. Processi eruttivi e post-eruttivi

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: The anthropogenic impact of conventional energy sources encourages the utilization of revenable energy, as it has become a strategic commodity for economic growth. On the other hand, institutional stability is the prerequisite...

Description: Published

Description: 100484

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: JCR Journal

Description: The paper describes a simplified mathematical model aimed at fitting available hydrographs of floods from subglacial lakes reaching their peak almost linearly in time, the so-called fast-risingjökulhlaups. The simplifying idea is that the glacier can be treated as a block with fixed width, length and thickness, confining a subglacial lake with a constant cross-sectional area and variable level. We do not consider the role of heat transfer as suggested by many authors for fast-rising events. The model consists of two ordinary differential equations: conservation equation for the lake water and motion equation for the glacier. The glacier vertical movement is supposed to be governed by its own weight, the water pressure generated by the lake and by the forces acting on the lateral sides due to interaction between the glacier and the surroundings. The model has three free parameters and reproduces satisfactorily eight historical hydrographs observed originated by eight jökulhlaups in the Skaftá river (Iceland). These floods, of fast-rising type, are sourced from two ice cauldrons, the Eastern one being responsible of the largest floods (up to 3500 m^3/s). On average, the cauldrons drain almost every two years due to persistent geothermal activity beneath Vatnajökull glacier. This periodicity has a simple mathematical interpretation and is used to obtain another validation of the model.

Description: Published

Description: 100013

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: The current focus on mangroves as key ecosystems in mitigating the impacts of climate change has largely neglected the livelihoods of coastal dwellers interacting with mangroves. This article provides a review of scholarly and policy attention paid to these social groups and their means of struggle. It argues that the latest dominant governance discourse tying mangroves to blue carbon signifies a departure from catering to coastal people's interests and rights in mangroves. We describe the evolving discourses that have shaped mangrove use and conservation in the Philippines since the 1970s. While the mid-century preoccupation with mangrove conversion to fish farms gradually gave way to the pursuit of community-based mangrove conservation in the late 1980s and 1990s, recent experiences suggest a comparably weakened focus towards recognizing local access and use patterns. We contend that the present blue carbon framing of mangroves, which harbours technocratic and financialized ideals of sustainability, poses a fundamental disadvantage to local users of mangroves. We conclude by reflecting on ways to redress this trend via a new framing of mangroves.

Description: Agricultural extension is booming. This interest is critical in the context of numerous pressing issues linked to agrarian change and rural development. Because of its importance, extension has attracted significant critique for its persistent exclusion of social and political factors. In this light, the history of extension can be thought of as a paradigm composed of approaches aimed at increasing agricultural production through the transfer of technologies from experts to farmers, and a series of criticisms of technology transfer as hampered by neglect of socio-political factors, a process labelled ‘rendering technical’. By reviewing criticisms of extension for its rendering of socio-political factors, we account for the rendering of power, place, and people. Equally important, we offer examples that consolidate critiques in order to open the possibility that humanized extension may more successfully support farmers. Our review is an effort to engage extensionists in order to speak about power to those who attempt to speak truth to power.

Description: Understanding the multidimensionality of microplastics is essential for a realistic assessment of the risks these particles pose to the environment and human health. Here, we capture size, shape, area, polymer, volume and mass characteristics of 〉60,000 individual microplastic particles as continuous distributions. Particles originate from samples taken from different aquatic compartments, including surface water and sediments from the marine and freshwater environment, waste water effluents, and freshwater organisms. Data were obtained using state-of-the-art FTIR-imaging, using the same automated imaging post-processing software. We introduce a workflow with two quality criteria that assure minimum data quality loss due to volumetric and filter area subsampling. We find that probability density functions (PDFs) for particle length follow power law distributions, with median slopes ranging from 2.2 for marine surface water to 3.1 for biota samples, and that these slopes were compartment-specific. Polymer-specific PDFs for particle length demonstrated significant differences in slopes among polymers, hinting at polymer specific sources, removal or fragmentation processes. Furthermore, we provide PDFs for particle width, width to length ratio, area, specific surface area, volume and mass distributions and propose how these can represent the full diversity of toxicologically relevant dose metrics required for the assessment of microplastic risks.

Description: Precise characterization of the mechanical properties of gelatin, a classic analog of the elastic crust, is necessary for scaling the mechanical models of the Earth's crust behavior in laboratory experiments. Here we reassess how to accurately calculate the Young modulus (E) of gelatin contained in experimental tanks. By means of dedicated analog experiments and finite element simulations, we estimate the bias introduced by using equations appro­ priate for a half-space to interpret the subsidence due to a cylindrical surface load applied on the gelatin. In the case of a standard experimental setup with gelatin adhering to the tank wall, we find E is overestimated by at least 5% for a box with lateral size smaller than 20 times the cylinder diameter. In addition, we deduce a correction factor to be applied when using an analytical formula. We confirm that measuring the shear velocity leads to accurate estimates for the rigidity of gelatin. We also propose a new method for in situ Young's modulus estimation, relying on the length of air-filled propagating crack. Indeed, for a given injected volume, this length depends only on the density contrast between air and gelatin and on the Young's modulus of the gelatin. The fracture toughness of the gelatin is estimated independently. Direct comparison between fracture toughness and Young's modulus shows that for a given Young's modulus, salted gelatin has a higher fracture toughness than unsalted gelatin.

Description: Published

Description: 228901

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: The interaction and competition between magmatic and tectonic processes mostly control the spatial distribution and morphology of monogenetic volcanoes. The Central Anatolian Volcanic Province, situated in a strike slip environment, provides a remarkable opportunity to understand this relationship. We defined six monogenetic clusters and analyzed 540 Quaternary monogenetic volcanoes in terms of morphological and spatial characteristics. There is no distinct correlation among the morphological parameters of scoria cones or lava domes, possibly owing to the various factors and the sporadic nature of magmatic activity in the region. Our detailed multivariate statistical and vent alignment analyses together with several implications in the literature reveal that the CAVP is a tectonically-controlled intraplate volcanic field, which is mostly driven by regional deformations. The presence of both clustered and non-clustered vent distributions and the petrological characteristics of the volcanics within the region indicates that the dikes are derived directly by the pre-existing melt-bearing heterogeneous mantle (i.e., Egrikuyu monogenetic field) or the independent and short-lived shallow or deep crustal magma reservoirs (i.e., Nevsehir-Acig & ouml;l volcanic field). The local changes in the stress regimes and crustal lithology result in variations of field shape, spatial vent distribution, and vent alignments throughout the region. The triggering mechanisms for the initiation of the Quaternary volcanism in the region can be the lithosphericscale Central Anatolian fault zone, here considered as an immature rift zone where Erciyes volcanic field is developed and behaves as a possible magmatic transfer zone. Tuz G & ouml;l & uuml; fault zone as a western border of the so-called rift basin in the region is mostly responsible for the crustal propagation of magma, and the kinematic changes along this fault zone (i.e., strike-slip to normal) mostly shaped the spatial vent distributions and alignments of the clusters in its close proximity (e.g., Hasandag-Kegiboyduran volcanic field).

Description: Published

Description: 107280

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: The SYM-H and AE geomagnetic indices can be considered as proxies of the response of the Earth’s magnetosphere and ionosphere to solar magnetic activity. They indirectly monitor some electric current systems which flow in the ionosphere and magnetosphere whose dynamics are directly or indirectly related to the Sun– Earth interaction. Consequently, their temporal changes reflect processes occurring in the near-Earth space, which contribute differently to the overall magnetosphere–ionosphere dynamics. The aim of this work is to characterize the nature of these two geomagnetic indices by following a complex system approach and applying a novel formalism, e.g., the EMD-based dominant amplitude multifractal formalism (EMD-DAMF). A set of complexity measures, i.e., the Hurst exponent (H), the singularity width (𝛥𝛼) and the spectrum width (𝛥𝑓), is evaluated for both geomagnetic indices analyzing data recorded during the last two solar cycles. One of the most significant findings of this study is the absence of relevant differences between the two solar cycles in terms of complexity measures for both geomagnetic indices, suggesting that only the occurrence and the frequency of geomagnetic storms and substorms affect the Hurst exponent and the singularity widths of SYM-H and AE indices. Moreover, while the AE index complexity measures do not show a significant dependence on geomagnetic activity, the SYM-H index shows a reduction in its complexity features during the geomagnetic storms, manifesting a more persistent behavior and moving from a (mono)fractal-like to a multifractal-like behavior when passing from quiet to disturbed periods. Finally, our findings are consistent with previous works on the forecast horizon of the geomagnetic activity as well as on the relation between the high-latitude ionosphere and the low-latitude magnetosphere, thus confirming the importance of providing higher resolution measures for correctly dealing with several Space Weather phenomena.

Description: Published

Description: 105583

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: In this paper, echo occurrence rates for the Dome C East (DCE) and the new Dome C North (DCN) radars are studied. We report the ionospheric and ground scatter echo occurrence rates for selected periods around equinoxes and solstices in the final part of the solar cycle XXIV. The occurrence maps built in Altitude Adjusted Corrected Geomagnetic latitude and Magnetic Local Time coordinates show peculiar patterns highly variable with season. The comparisons of the radar observations with the International Reference Ionosphere model electron density and with ray tracing simulations allow us to explain the major features of observed patterns in terms of electron density variations. The study shows the great potential of the DCE and DCN radar combination to the Super Dual Auroral Radar Network (SuperDARN) convection mapping in terms of monitoring key regions of the high-latitude ionosphere critical for understanding of the magnetospheric dynamics.

Description: Published

Description: 100684

Description: 2A. Fisica dell'alta atmosfera

Description: JCR Journal

Description: In this work, an approach is developed to study the seismicity associated with the impoundment and changes of a water reservoir (reservoir induced seismicity, RIS). The proposed methodology features a combination of a semi-analytical poroelastic model with an earthquake nucleation approach based on rate-and-state frictional law. The combined approach was applied to the case of the Pertusillo Lake, located in the Val d’Agri area (Italy), whose large seasonal water level changes are believed to induce protracted micro-seismicity (local magnitude ML 〈 3). Results show that the lake impoundment in 1962 could have produced up to 0.5 bar changes in Coulomb failure stress (DCFS), while the seasonal water level variation is responsible for variation up to 0.05 bar. Modeling results of the seismicity rates in 2001- 2014 show that the observed earthquakes are well correlated with the modeled DCFS. Finally, the reason that the seismicity is only observed at southwest of the Pertusillo Lake is provided, which is likely attributed to different rock lithologies and depletion caused by significant hydrocarbon exploitation in the northeastern sector of the lake.

Description: Published

Description: 802-810

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: During the 2016–2017, a seismic sequence struck the Central Italy, involving four regions (Umbria, Marche, Abruzzo and Lazio) and causing important damages and victims in inhabited areas such as Norcia and Amatrice towns. The strongest event of the seismic sequence was a Mw 6.5 event with epicenter at about 5 km far from the Norcia area, which is an intermontane basin prone to ground motion amplification. The historical town of Norcia and the surrounding hamlets were recently investigated by the microzonation activity, but information on the geometry and velocity are still partial considering the entire basin. Indeed, past studies aimed at reconstructing the elastic and geometrical properties focusing mainly on the northern part of the basin. Specifically in this paper, we integrated seismic and geological data to get a better knowledge of the properties of the Quaternary Norcia basin. A geological survey was carried out to provide a geological map and three geological cross-sections. We analyzed new seismic ambient vibrations data, collected by single-seismic stations, to infer the distribution of resonant frequency (f0) for the entire basin. We used passive arrays of seismic stations to better define the velocity profiles of the area. In the northern part of the basin, two 2D arrays with elliptical-like shapes were deployed showing strong discrepancies of the elastic soil properties in proximity of Norcia town. We found shear-wave velocities of the near-surface profile of about 300–400 and 500–800 m/s in presence of palustrine and alluvial fan deposits, respectively. Further, the values of f0 are abruptly varying from 0.5 Hz in the SW sector of Norcia village up to 2 Hz in its NE sector. Ambient vibration data reveal less pronounced variation of f0 in the southern part of the basin, with resonant values that are almost in the range 1–1.3 Hz. In the southern sector, a 1D array was arranged along a 5-km line and was analyzed by means of seismic noise cross-correlation analysis suggesting the presence of a deeper seismic contrast. The integration of geophysical and geological results has allowed to infer insights on the subsurface geometry of the basin.

Description: Published

Description: 105501

Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica

Description: JCR Journal

Description: The relationships between volcanic activity and tectonics at the southernmost termination of the Main Ethiopian Rift (MER), East Africa, still represent a debated problem in the MER evolution. New constraints on the timing, evolution and characteristics of the poorly documented volcanic activity of the Dilo and Mega volcanic fields (VF), near the Kenya-Ethiopia border are here presented and discussed. The new data delineate the occurrence of two distinct groups of volcanic rocks: 1) Pliocene subalkaline basalts, observed only in the Dilo VF, forming a lava basement faulted during a significant rifting phase; 2)Quaternary alkaline basalts, occurring in the twovolcanic fields as pyroclastic products and lava flows issued frommonogenetic edifices and covering the rift-related faults. 40Ar/39Ar dating constrains the emplacement time of the large basal lava plateau to ~3.7 Ma, whereas the youngest volcanic activity characterising the twoareas dates back to 134 ka (Dilo VF) to as recent as the Holocene (Mega VF). Volcanic activity developed along tectonic lineaments independent from those of the rift. No direct relations are observed between the Pliocene, roughly N-S-trending major boundary faults of the Ririba rift and the NE-SW-oriented structural trend characteristic of the Quaternary volcanic activity. We speculate that this change in structural trend may be the expression of (1) inherited crustal structures affecting the distribution of the recent volcanic vents, and (2) a local stress field controlled by differences in crustal thickness, following a major episode of reorganization of extensional structures in the region due to rift propagation and abandonment

Description: Published

Description: 106989

Description: 1V. Storia eruttiva

Description: JCR Journal

Description: We present here the first attempt to understand the fast dynamics of an active basaltic volcano, namely Mt. Etna using soil gas radon measured in some sites located in strategic places around the volcano. Data were measured continuously from July 2015 to February 2017 and the raw signals were treated in order to filter out all possible periodic components that are normally due to non-volcanic factors, applying a method that does not require acquisition of other parameters, which are not always available. The residual signals highlighted seven anomalous changes, with radon values reaching levels from 2 to 5 times higher than the normal background. In six out of seven cases, anomalies were almost contemporaneous in all or almost all of the sites, indicating a common source for the observed radon variations. The pattern of anomalies suggests a transient wave-like propagation in the space/time domain, compatible with pressure-induced displacement of the gas. The observed patterns are most probably caused by the rapid upward motion of gas-rich magma into the volcano conduits, as almost all anomalies precede or accompany major volcanic events. In some cases, an alternative explanation could be the strong and sudden strain releases through earthquakes swarms, with consequent variations in the permeability of rocks at a large scale, given the apparent correlation between those anomalies and intense seismicity.

Description: Published

Description: 106267

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: Crystallization experiments on two pantellerites from Pantelleria, Italy, provide new evidence for the relationships between mineral phases in pantelleritic rocks aswell as the influence of temperature and redox conditions on mineral assemblages. Experiments were performed at 1 kbar with temperature ranging between 750–900°C, and fluid saturation conditionswith XH2O (=H2O/H2O+CO2) between 0 and 1. Redox conditionswere fixed at, or slightly below, the FMQbuffer. Results showthat at temperature of 900 °C pantelleriticmagmas arewell above the liquidus regardless their water content; we also observed a decrease in liquidus temperature (800°C) with increasingly reducing conditions. Mineral assemblages of the natural rocks have been successfully reproduced, particularly the relationship between fayalite and aenigmatite, which appear to be strongly controlled by melt peralkalinity, temperature and redox conditions. This is the first time that fayalitic olivine have been synthetized in experimental studies on pantellerites, which was found to be stable only for temperatures ≥750°C while amphibole can be stable at temperatures as high as 800°C at high fF2. Experimental results have been compared with the composition of mineral phases as well as with the results obtained from mineral equilibrium, geothermometry, and oxygen barometry studies on pantelleritic lava and tuffs from Pantelleria (Italy), Eburru (Kenya) and Menengai (Kenya). Petrological characteristics appear similar at different locations worldwide, with typical assemblages of anorthoclase and sodian clinopyroxene with variable fayalite, aenigmatite, Fe-Ti oxides and amphibole.

Description: Published

Description: 105793

Description: 4V. Processi pre-eruttivi

Description: JCR Journal

Description: The Doldrums transform system offsets the Equatorial Mid Atlantic Ridge by ~630 km at 7–8° N. This transform system consists of four intra-transform spreading centers (ITRs) bounded by five transform faults. The northernmost ITR is linked to the MAR axis by a ~ 180 km-long transform. Here, during two R/V A. N. Strakhov expeditions (S06 and S09), mantle peridotites were dredged along the transverse and median ridge of the transform, across the western flank of the ITR valley. Residual harzburgites were mainly sampled along the northern Doldrums transform valley, whereas plagioclase-bearing peridotites showing evidence for melt-rock interaction characterize the ITR domain. Petrological and geochemical observations reinforced by geochemical modelling are used to define the behaviour of trace elements during melt extraction and melt-rock reaction in our rocks. Results suggest that residual peridotites derive from mantle rocks that have undergone a degree of partial melting up to 12%, with melting likely starting at the transition of garnet-spinel stability fields, whereas peridotites which suffered melt-rock reactions have been divided into two types: (i) pl-impregnated peridotites, formed by migration of melts at high porosity and high melt-rock ratio; and (ii) refertilized peridotites, generated at reduced porosity, when small fractions of the same percolating melt crystallized clinopyroxene and minor plagioclase. We suggest that the refertilizing agent was a melt highly depleted in incompatible trace elements, in turn produced by an ultra-depleted mantle source. This mantle experienced previous degrees of melt extraction at the ridge axis, before being transposed laterally along the transform where it melted a second time during the opening of the intra-transform spreading segment.

Description: Published

Description: 105698

Description: 3A. Geofisica marina e osservazioni multiparametriche a fondo mare

Description: 2TR. Ricostruzione e modellazione della struttura crostale

Description: JCR Journal

Description: The Upper Cretaceous Postalm section in the Northern Calcareous Alps (Austria) exposes pelagic depositsof the northwestern Tethys whose cyclostratigraphy and palaeoenvironments were examined in thisstudy.The section displays rhythmic deposits of Santonian to late Campanian age (Gosau Group). The San-tonian/Campanian transition is characterised by condensed greyish carbonates, while the younger de-posits are composed of reddish foraminiferal packstones displaying distinct limestone-marl alternations.A biostratigraphic framework based on planktonic foraminifera and calcareous nannofossils is supportedby carbon and strontium isotope stratigraphy as well as magnetostratigraphy. The carbon isotope dataallow to correlate the Postalm section to other Tethyan reference sites and to identifyd13C events, such asthe Late Campanian Event. Spectral analyses of three independently assessed proxies (d13C, Fe contentand the thickness of limestone/marl couplets) in the upper, continuously exposed section part identified17 to 18 405 ka cycles spanning the mid to upper Campanian (Contusotruncana plummeraetoGansserinagansseriZones or CC21/UC15c to CC23a/UC16 nannofossil zones).

Description: Published

Description: 104704

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: The formation of Cenozoic mountain belts in the Mediterranean realm was preceded by tens of millions of years of subduction, forming volcanic arcs, and frontal contractional systems. In addition, subduction usually involves slab rollback and formation of oceanic backarcs. Although such structure must have influenced the orogeny of Mediterranean mountain belts, no active analog has been mapped with modern crustal-scale seismic methods. Here, we study the entire Calabrian subduction system to map the structure resulting from Tethys lithosphere subduction and slab rollback, in a process that must be akin to that operating during a phase of the formation of the Mediterranean orogenic belts. We present a crustal-scale cross section of the entire Calabrian subduction system obtained from on- and off-shore wide-angle seismic data. The 2D P-wave velocity section shows spatially abrupt (〈5 km of profile distance) structural and petrological transitions from the Ionian sedimentary wedge and Calabrian arc, to the rifted NW Calabrian margin, where the Quaternary Aeolian arc is emplaced. The margin, then, transitions northwards into the Marsili backarc region, where exhumed mantle and localized volcanism occurred during its formation. This complex structure implies rapid temporal and spatial changes between magmatic and amagmatic processes, and between compressional and extensional regimes during the evolution of this subduction system. We find that some terranes involved in the Alpine orogeny share petrological and tectonic similarities with some domains of the Calabrian subduction system. Based on the results of this study we propose the Calabrian Arc system as an analog for the subduction structuration that preceded the formation of Alpine orogenic systems.

Description: Published

Description: 116480

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: The Palinuro volcanic chain (PVC) is located about 80 km offshore the Campania region (Italy) in the southern sector of the Tyrrhenian Sea. The chain consists of 15 volcanic edifices aligned in an E-W direction with two distinct major seamounts (Palinuro and Glabro). They cover a 90 km long and 20 kmwide area, with a present-day volume of 2700 km3. Palinuro volcanism emplaced between 0.8 and 0.3 Ma, although shallow seismicity and hydrothermalism indicate an ongoing volcanic activity. A geomorphological analysis of the volcanic chain and data from a multichannel seismic profile reveal large volumes of buried chaotic material suggesting gravity mass sliding from the volcano flanks and slide scars. A stability analysis of the Palinuro flanks has been carried out to determine the sectors potentially prone to sliding in case of shallow volcanic earthquakes. Landslides are simulated by adopting a scenario-based approach. Tsunamis induced by these mass movements and their propagation across the Tyrrhenian Sea are modeled. Results suggest that shallow earthquakes (M ~4.6–4.8) are able to destabilize the flanks of the volcanic chain generating slope failures. Sliding volumes in the order of 1.5 km3 and 2.4 km3 may induce waves as high as 1.5 and 6 m, respectively, along the peri-Tyrrhenian coast. Our results underline the need for further investigations on the stability of the submarine volcanoes of the Tyrrhenian basin. These volcanoes are still poorly known although their instability could trigger large tsunamis along the southern Italy coastal sectors. Our recommendation is that multiparamertic monitoring networks on PVC and periodic oceanic cruises should be put into action, and further that a systematic evaluation of the tsunami hazard related to possible sliding phenomena on the flanks of the Tyrrhenian seamounts should be performed

Description: Published

Description: 107025

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: Tetrapod ichnology is a powerful tool to reconstruct the faunal composition of Middle Triassic ecosystems. However, reconstructions based on a single palaeoenvironment provide an incomplete and impoverished picture of the actual palaeodiversity. In this paper, we analyse Middle Triassic tetrapod ichnoassociations from the detrital Muschelkalk facies of the Catalan Basin of northeast Spain, ranging from terrestrial to coastal settings. We identified two main tetrapod ichnoassociations, preserved in two different palaeoenvironments, comprising the following ichnogenera and morphotypes: Procolophonichnium, Chelonipus, Rhynchosauroides, Rotodactylus, Chirotherium, Isochirotherium, Sphingopus, and indeterminate chirotheriids. We also statistically analyse a database of all known Middle Triassic tetrapod footprint localities worldwide; this database includes, for each track locality, the precise age, the palaeoenvironment and the presence/absence of ichnotaxa. Our results on the composition of ichnofauna within the palaeoenvironments of the Catalan Basin are integrated into this database. This approach allows us to revisit the palaeoenvironmental bias linked to the marine transgression that affected the Western Tethys region. Tetrapod ichnoassociations reveal the following palaeoenvironmental patterns: (1) in coastal settings, ichnoassociations are Rhynchosauroides-dominated and diversity is relatively low; (2) in terrestrial settings and those with less marine influences, ichnoassociations are non-Rhynchosauroides-dominated, usually characterised by more abundant chirotheriid tracks and, generally, a higher track diversity. The correlation between tetrapod ichnoassociations and sedimentary facies reveals how palaeoenvironmental constraints influenced faunal assemblages, especially those of the Middle Triassic of the Western Tethys region. Ichnoassociations allow the ecological response of tetrapod faunas to the environmental changes to be inferred for this critical time interval. Marine transgressions strongly influenced tetrapod ecosystems: environmental conditions were key for the faunal recovery in the aftermath of the end-Permian extinction, with the settlement of the so-called modern faunas and the rise of the dinosaur lineage.

Description: Published

Description: 110204

Description: 1A. Geomagnetismo e Paleomagnetismo

Description: JCR Journal

Description: Processes of crystal-mush remobilization bymaficmagma recharges are often related to the outpouring of large volumes of silicic melt during caldera-forming eruptions. This occurred for the Campanian Ignimbrite (CI) eruption (Campi Flegrei, Italy), which produced a voluminous trachy-phonolitic ignimbrite in southern-central Italy about 40 ka ago.We focussed on the proximal-CI deposits at San Martino that are composed of a main sequence of early-erupted, crystal-poor units and a late-erupted (post-caldera collapse) crystal-rich Upper Pumice Flow Unit (UPFU). Detailed micro-analytical geochemical data were performed on glasses and crystals of pyroclasts from these deposits and coupledwith Sr-Nd isotopic measurements on glasses. Results show that the CI eruption was fed by two distinctmelts for the early-erupted units and the late UPFU, respectively. The glasses of the early erupted units have negative Eu anomalies and show more evolved compositions and higher Nd isotope ratios than those of the UPFU, which have positive Eu/Eu*. The magmas of the early units formed the main volume of eruptiblemelt of the CI reservoir, and are interpreted as having been extracted from cumulate crystal-mush without a vertical geochemical gradient within the magma reservoir. The data indicate that the generation of the distinctive UPFU melts involved the injection of a new batch of mafic magma into the base of the CI reservoir. The mafic magma allowed heating and reactivation of the CI crystal-mush by melting of low-Or sanidines (+/− low-An plagioclases), leaving high-An plagioclases and high-Mg# clinopyroxenes as residual phases and a crystal-mush melt, made of 20% of the initial mush interstitial melt (with a composition similar to the early erupted units) and 80% of sanidine melt. When the mush crystallinity was sufficiently reduced, the mafic magma was able to penetrate into the reactivated crystal-mush, mixing with variable proportions of crystalmush melt and generating cooler hybrid melts, which underwent further crystallization of high-Or sanidine at variable degrees (10–25%). Finally, possibly a short time before the eruption, the UPFU magmas were able to mix and mingle with the crystal-poor eruptible melts still persisting in the CI reservoir at the time of UPFU emission. We suggest that the complex mechanisms described for themagma evolution feeding the CI eruption may occur whenever a crystal-mush is reactivated by new mafic magma inputs .

Description: Published

Description: 105780

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Accurate quantification of the emission rate of sulphur dioxide (SO 2 ) from volcanoes provides both insights into magmatic processes and a powerful monitoring tool for hazard mitigation. The primary method for measuring magmatic SO 2 is Differential Optical Absorption Spectroscopy (DOAS) of UV scattered sunlight spectra, in which a reference spectrum taken outside the plume is used to quantify the SO2 slant column density inside the plume. This can lead to problems if the reference spectrum is contaminated with SO2 as this will result in a systematic underestimation of the retrieved SO2 slant column density, and therefore emission rate. We present a new analysis method, named ―iFit‖, which retrieves the SO 2 slant column density from UV spectra by directly fitting the measured intensity spectrum at high spectral resolution (0.01 nm) using a literature solar reference spectrum and measured instrument characteristics. This eliminates the requirement for a measured reference spectrum, providing a ―point and shoot‖ method for quantifying SO 2 slant column densities. We show that iFit retrieves correct SO2 slant column densities in a series of test cases, finding agreement with existing methods. We propose that iFit is suitable for both traverse measurements and permanent scanning stations, and could be integrated into volcano monitoring networks at observatories. Finally, we provide an open source software implementation of iFit with a user friendly graphical interface to allow users to easily utilise iFit.

Description: Published

Description: 107000

Description: 5V. Processi eruttivi e post-eruttivi

Description: JCR Journal

Description: The Apennines-Sicilian-Maghrebian fold-and-thrust belt originated from the subduction of the Alpine Tethys and the later collision of drifted continental blocks against the African and Apulian paleomargins. From North to South, the Sicilian Fold-and-Thrust Belt (SFTB) is divided in four main tectono-stratigraphic domains: (1) the Calabro-Peloritani terrane, drifted from the European margin, (2) the remnants of the Alpine Tethys accretionary Wedge (ATW) related to the subduction of the Tethys, (3) the folded and thrusted platform (Panormide) and deep-water (Imerese-Sicanian) series of the offscrapped African margin, and (4) the African foreland (Hyblean). Unfortunately, scarce quality seismic lines and outcrops of key tectono-stratigraphic units make the structure and dynamic evolution of the central-eastern part of the SFTB controversial. First, this study outlines through a review of the tectono-stratigraphic evolution of the central-eastern sector of the Sicilian orogen, the major remaining issues concerning: (1) the occurrence of inferred Alpine Tethys units far from the region where the remnants of the ATW outcrop (Nebrodi Mountains); both, in a forearc position above the Peloritani block to the North and in an active foreland context along the present day southern front of the belt; and (2) the diverging tectonic styles, from stacked large-scale tectonic nappes to foreland imbricated thrust systems rooted into a main basal décollement. Secondly, new constraints are given using analogue modeling to test mechanically the hypothesized structural and tectono-stratigraphic evolution of the SFTB. The experiment simulates the orogenic evolution of the SFTB at crustal-scale, from the Oligocene Tethys subduction, to the Middle Miocene-Late Pliocene continental collision between the European and African paleomargins. The tectono-stratigraphic synthesis is used to model the first-order mechanical stratigraphy of the sedimentary units involved in the Sicilian belt, as well as the imprint of the African margin structural inheritance. The experiments succeed in reproducing the general structure and tectono-stratigraphic evolution of the SFTB. In particular, the models support field observations hypothesing a gravity-driven origin of the inferred Alpine Tethys units intercalated within the forearc and foreland syntectonic sedimentation. Moreover, the model testifies of the main tectonic steps that led to the SFTB building. First, a low-tapered accretionary wedge was accreted above the Alpine Tethys oceanic crust from the Oligocene to the Early Miocene. The following underthrusting of the stretched African continental margin and its frontal Panormide platform shortened and thickened the accretionary wedge. This phase provided favorable conditions for significant pulses of reworked Alpine Tethys units that intercalated within the forearc and foredeep successions. During the Middle-Miocene, the décollement of the African Meso-Cenozoic cover (Panormide platform and Imerese-Sicanian deep-water basin) enhanced a deep-seated deformation phase, along with duplexing of the Panormide platform beneath the Alpine Tethys wedge leading to its emersion. Since the Late Messinian, activation of basement faults led to a generalized emersion of the orogenic units through large-wavelength fold culminations accompanied by syntectonic deposition at their southern limbs. Concurrently, the prism front was partly indented to the southeast by the thick and locally already emerged Hyblean platform.

Description: Published

Description: 103257

Description: 1T. Struttura della Terra

Description: JCR Journal

Description: Open vent basaltic volcanoes account for a substantial portion of the global atmospheric outgassing flux, largely through passive degassing and mild explosive activity. We present volcanic gas flux and composition data from Yasur Volcano, Vanuatu collected in July 2018. The average volcanic plume chemistry is characterised by a mean molar CO2/SO2 ratio of 2.14, H2O/SO2 of 148 and SO2/HCl of 1.02. The measured mean SO2 flux in the period of 6th to 9th July is 4.9 kg s−1 . Therefore, the mean fluxes of the other species are 7.5 kg∙s −1 CO2, 208 kg∙s −1 H2O and 4.8 kg∙s −1 HCl. The degassing regime at Yasur volcano ranges from ‘passive’ to ‘active’ styles, with the latter including Strombolian activity and spattering. Gases emitted during active degassing are enriched in SO2 over HCl and CO2 over SO2 relative to passive degassing, with CO2/SO2 ratios of 2.85 ± 0.17, SO2/HCl of 1.6 ± 0.22, and H2O/SO2 of 315 ± 78.8. Gases emitted during passive degassing have CO2/SO2 ratios of 1.96 ± 0.12, SO2/ HCl of 0.50 ± 0.07 and H2O/SO2 of 174 ± 43.5. We use a model of volatile degassing derived from melt inclusion studies (Metrich et al., 2011), combined with our observations of chemical variations in the outgassing bubbles to propose a mechanism for magma degassing in the conduit at Yasur. We envisage a shallow conduit filled with crystal-rich magma, forming a viscous and mobile plug that develops an effective yield strength from the surface to a depth of at least 2000 m, in which bubbles are trapped, grow, ascend towards the surface and burst in a typical Strombolian eruption. Deeper bubbles released during active degassing are enriched in CO2 and SO2 compared to bubbles released during ‘passive degassing’, which are sourced from close to the surface, and are, consequently, HCl-rich.

Description: Published

Description: 106869

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: The ability of plant roots to penetrate soils is affected by several stimuli exerted by the surrounding medium, such as mechanical stresses and chemical stimuli. Roots have developed different adaptive responses, such as increase or decrease of the elongation rate of the apical region and swelling or shrinking of its diameter. We propose a mathematical model aimed at explaining the dynamic evolution of plant roots during the penetration into the soil. We treat the root as a cylinder and the root–soil interaction as a purely mechanical inclusion problem. In particular, the root dynamic evolution is based on a modified version by one of the authors of the extended universal law of West, Brown, and Enquist. Coupling the solution of the mechanical problem and the growth equation, we compare the theoretical results with experimental data collected in artificial and real soils. In this work, we propose a plausible interpretation of the experimental results of the root behavior during the growth inside the surrounding soil medium.

Description: Published

Description: 103344

Description: 7A. Geofisica per il monitoraggio ambientale

Description: JCR Journal

Description: This study presents a detailed analysis of minor seismic sequences recorded in the Amatrice-Norcia area (central Italy) before 2016 when the most important seismic sequence of the last 40 years struck the region with the Mw 6.0 Amatrice and the Mw 6.5 Norcia earthquakes. We observe that, in the four decades before the 2016–2018 Amatrice-Visso-Norcia sequence, the instrumental seismicity rate is low, with maximum magnitudes lower than Mw 4.0, and is characterized by different types of behaviours as single shock events, swarms and minor se- quences. For the first time, we relocate the minor seismicity recorded before 2016 by the Italian National Seismic Network of the Istituto Nazionale di Geofisica e Vulcanologia by applying the nonlinear inversion code Non- LinLoc in a local velocity model. Revised earthquake locations of the past seismic sequences are compared to the recent 2016–2018 seismicity in order to investigate some possible correlations with the seismogenic structures reactivated in 2016. With this goal, we also integrated our new hypocentral locations with fault plane solutions and geological data to interpret our results with respect to the 2016–2018 seismicity. Our results show how some of the structures identified by the minor seismicity before 2016 were reactivated during the recent sequence, while others seismic structures remained silent. We therefore highlight how the study of minor seismic sequences provides important information about the seismogenic attitude of less active or less known seismogenic struc- tures with consequent impact on the evaluation of the seismic hazard.

Description: Published

Description: 228858

Description: 4T. Sismicità dell'Italia

Description: JCR Journal

Description: We present the first isotopic (noble gases and CO2) characterization of fluid inclusions coupled to Raman microspectroscopy analyses in mantle xenoliths from Central Mexico, a geodynamically complex area where the Basin and Range extension was superimposed on the Farallon subduction (terminated at 28 Ma). To characterize the isotopic signature of the Central Mexican lithospheric mantle, we focus on fluid inclusions entrapped in mantle xenoliths found in deposits of the Joya Honda maar (JH), a Quaternary monogenetic volcano belonging to the Ventura Espiritu Santo Volcanic Field (VESVF) in the state of San Luis Potosí (central Mexico). Thirteen ultramafic plagioclase-free xenoliths were selected, all exhibiting a paragenesis Ol 〉 Opx 〉 Cpx 〉 〉 Sp, and being classified as spinel-lherzolites and harzburgites. All xenoliths bring textural evidence of interstitial glass veins bearing dendritic trails of secondary melt and fluid inclusions (composed of silicate glass ± CO2 ± Mg-Ca carbonates ± pyrite). These are related to pervasive mantle metasomatism driven by carbonate-rich silicate melt. The Ar and Ne systematics reflect mixing between MORB-like upper mantle and atmospheric fluids, the latter interpreted as reflecting a recycled air component possibly inherited from the Farallon plate subduction. The 3He/4He ratios vary between 7.13 and 7.68 Ra, within the MORB range (7–9 Ra), and the 4He/40Ar* ratios (0.4–3.11) are similarly close to the expected range of the fertile mantle (1–5). Taken together, these pieces of evidence suggest that (i) either the mantle He budget was scarcely modified by the Farallon plate subduction, and/or (ii) that any (large) crustal contribution was masked by a later metasomatism/refertilization episode, possibly during the subsequent Basin and Range extension. A silicate melt-driven metasomatism/refertilization (revealed by the association between glass veins and fluid inclusions) is consistent with calculated helium residence time for the Mexican lithospheric mantle (20 to 60 Ma) that overlaps the timing of the above geodynamic events. We propose that, after the refertilization event (e.g., over the last ~20 Ma), the lithospheric mantle has evolved in a steady-state, becoming slightly more radiogenic. We also estimated 3He fluxes (0.027–0.080 mol/g), 4He production rates (340–1000 mol/yr), and mantle CO2 fluxes (3.93 × 107 mol/yr to 1.18 × 108 mol/yr) using the helium isotopic values measured in JH mantle xenoliths. Finally, the JH xenoliths exhibit CO2/3He ratios comparable to those of the upper mantle (from 3.38 × 108 to 3.82 × 109) but more positive δ13C values (between - 1.0 and - 2.7‰), supporting the involvement of a crustal carbonate component. We propose that the metasomatic silicate melts recycled a crustal carbonate component, inherited by the Farallon plate subduction.

Description: Published

Description: 120270

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Through a systematic integrated approach, which combined lithostratigraphic, geochronological and geochemical analyses of tephra from near-source sections of the peri-Tyrrhenian volcanoes and mid to distal settings, here we provide an improved tephrochronological framework for the Marine Isotope Stage 11c interglacial (MIS 11c, ~425e395 ka) in the Central Mediterranean area. Specifically, we present the complete geochemical dataset and new high-precision 40Ar/39Ar ages of the previously poorly characterized earliest pyroclastic products of the Vico volcano (420e400 ka), including the Plinian eruptions of Vico a and Vico b and the immediately post-dating lower magnitude explosive events. Furthermore, we also provide new geochronological and geochemical data for the distal tephra layers preserved in the aggradational succession of the Tiber delta (San Paolo Formation), Roman area, which records sea level rise relating to the MIS 12 (glacial) to MIS 11 (interglacial) transition. Five pyroclastic units were recognized in Vico volcanic area, four out of which, Vico a, Vico b, Vico btop (a minor eruption immediately following Vico b and temporally very close to it) and Vico d were directly dated at 414.8 ± 2.2 ka, 406.5 ± 2.4 ka, 406.4 ± 2.0 ka and 399.7 ± 3.2 ka respectively (2s analytical uncertainties). These new data allow a critical reappraisal of the previously claimed identifications of Vico tephra from mid-distal to ultra-distal successions (i.e., Vico-Sabatini volcanic districts, Roman San Paolo Formation and Castel di Guido archaeological site, Sulmona Basin, Valdarno and Lake Ohrid), which were unavoidably biased by the poor and incomplete geochemical and geochronological reference datasets previously available. Such an improvement of the tephrochronological framework brings great benefits to any future investigations (e.g., paleoclimatology, archaeology, active tectonic, volcanology) in the dispersal areas of the studied eruptions at the key point in time that is MIS 11.

Description: Published

Description: 106470

Description: 1V. Storia eruttiva

Description: JCR Journal

Description: Archaeological investigations carried out at Case Bastione (Enna, central Sicily) provide a key insight into the cultural and environmental changes that occurred during the transition from the Copper Age to the Bronze Age. Preliminary data of an ongoing paleoenvironmental reconstruction through archaeobotanical analyses are here presented. The selective exploitation of vegetation, the adaptation of lifestyle to local resources, and changing climatic conditions are analysed using different on-site and off-site environmental and archaeological proxies. The environment around the site was constituted by mixed oak woodland. Dietary preferences were reconstructed through the analysis of carpo-remains. Isotopic values provide new data on the 4.2 ka BP event and its effects on vegetation in central Sicily. In a whole, first results from Case Bastione give new light to human choices of vegetal resources exploitation. Comparison of the local results with the regional pollen data support the hypothesis that the growth in population and settlement in the inland part of the island since the Late Copper Age may reflect changing climatic conditions in coastal areas.

Description: Published

Description: 102332

Description: 7SR AMBIENTE – Servizi e ricerca per la società

Description: JCR Journal

Description: The Canary Islands, in the eastern Atlantic, are among the most enigmatic Oceanic Island provinces on Earth, as the mantle source feeding its volcanism exhibits wide spatial heterogeneity and a multiplicity of sources. Multiisotope whole-rock studies have long revealed the presence of a recycled oceanic crust/lithosphere component in the mantle source. However, noble gas systematics have been more challenging to interpret, and the available carbon isotope data is limited and cannot support/dismiss this interpretation. Here, we present the very first isotopic characterisation of CO2 and noble gases (He-Ne-Ar) in fluid inclusions (FI) in minerals hosted in mantle xenoliths from El Hierro, the youngest and westernmost island of the Canary volcanic archipelago. Six fresh xenoliths from El Julan cliff valley were analysed (3 spinel lherzolites and 3 spinel harzburgites). We find carbon isotopic compositions of CO2 in FI (δ13C) ranging from 􀀀 2.38 to 􀀀 1.23‰ in pyroxenes and from 􀀀 0.19 to +0.96‰ in olivines. These unusually positive δ13C values, well above the typical mantle range (􀀀 8‰ 〈 δ13C 〈 􀀀 4‰), prove, for the first time, the presence of a recycled crustal carbon component in the local source mantle. We interpret this 13C-rich component as inherited from a mantle metasomatism event driven by fluids carrying carbon from C. In contrast, our El Hierro xenoliths identify a depleted mantle-like He signature, with an average Rc/Ra ratio (3He/4He normalised to air ratio and corrected for atmospheric contamination) of 7.45 ± 0.26 Ra. The involvement of depleted mantle-like fluids, variably admixed with air-derived components (possibly recycled via paleo-subduction event(s)), is corroborated by Ne-Ar isotopic compositions. The depleted mantle-like He signature suggests instead the involvement of a primordial He source in the local lithospheric mantle and indicates a marginal role played by past subduction events in modifying the local mantle He budget. When put in the context of previous 3He/4He measurements in FI and surface gases along the Canary archipelago, our results confirm an overall west-to-east decrease of Rc/Ra ratios, which may be interpreted as due to increasing contributions from the African sub-continental mantle, the addition of radiogenic 4He during magma migration in the oceanic crust (whose thickness increases eastward) and/or magma ageing.

Description: Published

Description: 106414

Description: 1V. Storia eruttiva

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: Volcanic activity is widespread within the inner Solar system and it can be commonly observed on rocky planets. In this work, we analyse the structures of Pavonis Mons in the Tharsis volcanic province of Mars by performing structural mapping, azimuth, and topographic distribution of linear features on the flanks of Pavonis, such as grabens and pit chains. We tested whether their formation is to be ascribed to the volcano dynamics and magmatic activity or the tectonics. Through the length size distribution and fractal clustering analyses of the structural features, we found that large grabens are vertically confined in the upper mechanical layers of the brittle crust whereas pit chains penetrate the whole crust up to the magmatic source, indicating that they can be considered the main feeders of Pavonis Mons. We inverted the topography with dykes and faults models to test whether grabens at the surface are the expression of intrusions at depth and we suggest that thin dykes inducing normal faulting are the most likely mechanism. Furthermore, two azimuthal distribution of the grabens are identified: concentric grabens occur on the volcano summit while linear grabens at its base show NE-SW trend as the Tharsis Mons volcanos alignment. The occurrence of linear grabens suggests that Pavonis likely experienced a phase of active rifting with the formation of such structures, followed by a phase of volcano growth and concentric magma intrusions when volcano and magma chamber dynamics prevailed.

Description: Published

Description: 107148

Description: 2V. Struttura e sistema di alimentazione dei vulcani

Description: JCR Journal

Description: A new data assimilation procedure in the International Reference Ionosphere UPdate (IRI UP) method has been recently implemented. This new procedure relies on the assimilation of vertical total electron content (vTEC) values from a Global Navigational Satellite Systems ground-based receivers network, calibrated through the Seemala’s method (IRI UP Seemala), to obtain an updated description of F2-peak ionospheric characteristics over the South-African region. The main purpose of this paper is to investigate how the use of different vTEC calibration methods affects the IRI UP method. In this work, the IRI UP method is applied on periods already analysed in the past (several quiet and disturbed periods in 2017 and 2018), but assimilating vTEC values calibrated through the Ciraolo’s method (IRI UP Ciraolo). In this way, it is possible to make a homogeneous and fair comparison between results obtained with the two different calibration methods. Overall, it emerges that IRI UP Ciraolo models foF2 with a precision that is always greater than the IRI UP Seemala’s one, mainly at nighttime and solar terminator hours, for both quiet and disturbed periods; while slight improvements are achieved during daytime hours. Their accuracy is instead quite similar. Anyhow, the IRI foF2 modeling over the South-African region is significantly improved by both procedures, thus providing a valuable tool to improve IRI model performances.

Description: Published

Description: 2138-2151

Description: 2A. Fisica dell'alta atmosfera

Description: 1IT. Reti di monitoraggio e sorveglianza

Description: JCR Journal

Description: Accurately reconstructing the scale and timing of dynamic processes, such as Middle-Late Pleistocene explosive volcanism and rapid climatic changes, requires rigorous and independent chronological constraints. In this framework, the study of distal volcanic ash layers, or tephra, transported and deposited over wide regions during explosive volcanic eruptions, is increasingly being recognised as a fundamental chronostratigraphic tool for addressing these challenging issues. Here we present a high-resolution distal tephra record preserved in the lacustrine sedimentary succession of the Fucino Basin, central Italy. The investigated record spans the 430-365 ka time interval, covering the entirety of Marine Isotope Stage 11 (MIS 11), and provides important insights into peri-Tyrrhenian potassic explosive volcanism from sources located in central Italy against a backdrop of Mediterranean palaeooclimate records. The succession of ash fall events of this time interval is reconstructed through a detailed lithostratigraphic, geochemical and 40Ar/39Ar geochronological characterization of the deposits preserved as discrete layers in the Fucino F4-F5 sediment core. This work is complemented by similarly detailed characterization of selected proximal pyroclastic units from the peri-Tyrrhenian potassic volcanoes. Geochemical fingerprinting of the tephra deposits by means of their major, minor and trace elements and Sr isotope composition indicates that all the thirty-two investigated ash layers derived from the peri-Tyrrhenian potassic volcanoes. The stratigraphically continuous succession of the Fucino tephra layers allowed the development of a fully independent, 40Ar/39Ar age-constrained, Bayesian age-depth model for the investigated time interval. The age-model allows us to establish modelled ages for the tephra layers within the succession that are not directly dated. The resulting dated tephra record clearly reveals a highly time resolved and previously unparalelled chronicle of explosive activity from the Vulsini, Vico, Sabatini, Colli Albani and Roccamonfina volcanic complexes. Our study provides a benchmark and valuable geochemical and geochronological dataset to be used as a reference for any future development and application of the tephrostratigraphic methods across the central Mediterranean area both during the investigated 430-365 ka time interval, and deeper in time. This contribution underlines the importance of integrating proximal and distal sedimentary records to more accurately establish long-term and comprehensive volcanic eruption records.

Description: Published

Description: 103706

Description: 6A. Geochimica per l'ambiente e geologia medica

Description: JCR Journal

Description: Within subvolcanic plumbing systems, along volcanic conduits and post-eruptive emplacement, mineral textures and compositions are governed by complex kinetic (undercooling) and dynamic (convective) processes that deviate from theoretical models and equilibrium criteria. In this perspective, we have investigated the partitioning of major and trace cations between clinopyroxene and phonotephritic melt under convective stirring conditions at high degrees of undercooling (−ΔTnominal = 30–60 °C) and atmospheric pressure. We have integrated this novel data set with conventional static (no physical perturbation) clinopyroxene-melt compositions obtained under interface- and diffusion-controlled growth regimes. Results show that clinopyroxene growth kinetics and diffusion boundary layers caused by melt supersaturation are partly mitigated by the homogenizing effects of stirring. Because of continuous supply of fresh melt to the advancing crystal surface, the partitioning of major and trace cations is governed by local equilibrium effects, which are interpreted as the extension of equilibrium thermodynamic principles to non-equilibrium bulk systems. Major cations are incorporated into the clinopyroxene structure via the coupled substitution [M1Mg, TSi] ↔ [M1Ti, TAl] and in conformity with the thermodynamic mixing properties of CaMgSiO2, CaAl2SiO6, and CaTiAl2O6 components. The complementary relationship between lattice strain (ΔGstrain) and electrostatic (ΔGelectrostatic) energies of heterovalent substitutions is the most appropriate thermodynamic description for the accommodation of trace cations in the clinopyroxene lattice site (i.e., ΔGpartitioning = ΔGstrain + ΔGelectrostatic). The excess energy of partitioning ΔGpartitioning changes principally with Al in tetrahedral coordination and determines the type and number of charge-balanced and -imbalanced configurations taking place in the structural sites of clinopyroxene. An important outcome from dynamic stirring experiments is that superimposition of convective mass transfer on melt supersaturation phenomena causes the formation of Cr-rich concentric zones under closed system crystallization conditions. However, these Cr-rich zones do not correlate with enrichment in other compatible elements and depletion in incompatible elements, as would be expected in natural open systems characterized by input of more primitive magmas. While the convective transport acts to reduce the diffusive length scale of chemical species in the experimental melt, fresh Cr cations are more easily incorporated into the concentric zones due to crystal field effects. Together, our findings reveal that during magma ascent and emplacement, convective stirring may promote clinopyroxene crystallization and minimize kinetic effects on clinopyroxene zoning.

Description: Published

Description: 120531

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: Batu Tara is an active but poorly studied volcano located in the Lesser Sunda Archipelago (Indonesia). Its last known long-lasting eruptive phase, dating 2006–2015, was characterised by frequent short-lived explosions, similar in style and magnitude to those of the well monitored Stromboli volcano (Italy). On September 2014, we collected high-frequency multi-parametric measurements of the ongoing explosive activity to investigate the dynamics of intermediate-size volcanic explosions. We acquired synchronized acoustic, thermal and visible high-speed imaging data, and parameterized different spatial and temporal properties of each explosive event: i) maximum height and ejection velocity of bombs and plumes, ii) duration, iii) amplitude of acoustic and thermal transients, iv) acoustic and thermal energy, v) spectral features of the acoustic signals. The latter ones justify the assumption of a pipe resonance of the uppermost conduit section, likely in response to the arrival of over-pressurized gas at the free magma surface. The variability of the investigated parameters agrees with previous observations of intermediate-size explosions at other volcanoes, reflecting the complexity of the related source processes.

Description: Published

Description: 107199

Description: 5V. Processi eruttivi e post-eruttivi

Description: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Description: JCR Journal

Description: There is increasing recognition that both textural and compositional changes of clinopyroxenes crystallizing from mafic alkaline magmas are the direct expression of complex dynamic processes extending over a broad range of spatial and temporal scales. Among others, supersaturation and relaxation phenomena play a key role in controlling the final crystal cargo of variably undercooled magmas erupted from active alkaline volcanoes. Following this line of reasoning, we have carried out isothermal- isobaric, decompression, and cooling rate experiments on a basalt interpreted as the parental magma of mafic alkaline eruptions at Mt. Etna volcano (Sicily, Italy). The main purpose is to reconstruct and quantify the textural changes (i.e., length of major and minor axes, surface area per unit volume, area fraction, and maximum growth rate) of clinopyroxene upon variable pressures (30-300 MPa), temperatures (1,050-1,100 °C), volatile contents (0-5 wt.% H 2 O and 0-0.2 wt.% CO 2 ), and equilibration times (0.25-72 h). By integrating experimental data and thermodynamic modeling, the transition between interface-controlled (euhedral morphologies) and diffusion- controlled (anhedral morphologies) growth regimes has been determined at an undercooling threshold value of ~33 °C. Early melt supersaturation causes the fast growth of tiny clinopyroxenes with strong disequilibrium shapes, whereas an increasing relaxation time leads to the slow growth of large clinopyroxenes showing textural equilibration. According to these kinetic principles, both growth rate and relaxation time have been parameterized in relation to the crystal size distribution (CSD) analysis of naturally undercooled clinopyroxenes erupted during 2011-2012 lava fountain episodes at Mt. Etna volcano. Results indicate that the crystallization of microlites and microphenocrysts takes place under (dis)equilibrium growth conditions, in the order of ~10 0 -10 1 min (large undercooling, short equilibration time) and ~10 1 -10 2 h (small undercooling, long equilibration time), respectively. This temporal information allows to disentangle the cooling and decompression paths of Etnean magmas rising and accelerating along a vertically extended, highly dynamic plumbing system. While clinopyroxene microlites develop during the fast ascent of magmas (~10 0 -10 1 m s -1 ) within the uppermost part of the conduit or immediately before ejection from the vent, the onset of microphenocryst crystallization occurs at depth and continues within the plumbing system during the slow ascent of magmas (~10 -2 m s -1 ) that migrate through interconnected storage regions.

Description: Published

Description: 106225

Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici

Description: JCR Journal

Description: Mantle degassing transect across different tectonic units within a plate convergent setting has been well documented for oceanic convergent margins by systematic changes in geochemistry (e.g., 3He/4He, d13C, and CO2/3He) of hydrothermal gases. However, little is known about spatial variations in volatile geochemistry across a continental convergent margin. In this study, we identify a mantle degassing transect in the southeastern Tibetan Plateau using He-CO2 systematics of hydrothermal gases, which extends from India-Asia continental convergent margin to intra-continent extensional region. d13C-CO2 ( 11.8‰ to 3.1‰) and CO2/3He (1.7 108 to 7.1 1011) values of hydrothermal gases show large variations that are consistent with modification by secondary physico-chemical processes, such as multi-component mixing, hydrothermal degassing, and calcite precipitation. Three levels of He degassing can be recognized based on 3He/4He dataset (0.01–5.87 RA) of the hydrothermal gas samples and their distances to volcanic centers. A magmatic level He degassing (35–74% mantle He) is found near active and/or Quaternary volcanoes fed by mantle-derived magmas. With increasing distance to volcanic centers, the outgassed magmatic volatiles are gradually diluted by crustal components (e.g., radiogenic 4He), defining a transitional level He degassing (13–33% mantle He). The 3He/4He values (8.16–8.48 RA) of olivine phenocrysts indicate a MORB (mid-ocean ridge basalts)-type mantle source for the magmatic and transitional levels of He degassing that are localized in Quaternary volcanic fields. In contrast, a background level He degassing (〈12% mantle He) dominates the entire study area, and can be attributed to (i) degassing of sub-continental lithospheric mantle, and/or (ii) higher degrees of crustal contamination than those of the transitional level He degassing near volcanic centers. Combined with olivine 3He/4He data reported in this study and whole-rock 87Sr/86Sr data of host basalts from literature, source components of the mantle-derived magmas are suggested to include the MORB-type convective mantle, subducted Indian slab materials, and less degassed mantle materials, which can account for the possible decoupling between He and Sr isotope systematics. These findings delineate the origin and outgassing of mantle volatiles controlled by the India-Asia continental convergence, and would contribute to a better understanding of the deeply-sourced volatile emissions in these tectonic settings.

Description: Published

Description: 61-78

Description: 9T. Geochimica dei fluidi applicata allo studio e al monitoraggio di aree sismiche

Description: JCR Journal

Description: Declaration of interest was missed out in the published version. The authors have confirmed in the following context: ‘The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.’ The publisher would like to apologise for any inconvenience caused.

Description: Marine Neurotoxins, Volume Five provides comprehensive information on marine toxins present in the human food chain and the affecting targets relevant for the functioning of the brain and our nervous system, covering all the information ...

Description: The northern mid- to high-latitudes have the highest total number and area of lakes on Earth. Lake origins in these regions are diverse, but to a large extent coupled to glacial, permafrost, and peatland histories. The synthesis of 1207 northern lake initiation records presented here provides an analog for rapid landscape-level change in response to climate warming, and its subsequent attenuation by physical and biological feedback mechanisms. Our compilation reveals two peaks in northern lake formation, 13,200 and 10,400 years ago, both following rapid increases in North Atlantic air temperature. Placing our findings within the context of existing paleoenvironmental records, we suggest that solar insolationdriven changes in climate (temperature and water balance) that led to deglaciation and permafrost thaw likely contributed to high rates of northern lake formation during the last Deglacial period. However, further landscape development and stabilization dramatically reduced rates of lake formation beginning ~10,000 years ago. This suggests that temperature alone may not control future lake development; rather, multiple factors must align to enable a landscape to respond with an increase in lake area. We propose that land surfaces strongly geared toward increased lake formation were highly conditioned by glaciation. Thus, it is unlikely that warming this century will cause lake formation as rapid or as widespread as that during the last Deglacial period.

Description: The contribution from northern high latitude wetlands are a major uncertainty in the atmospheric methane (CH4) budget throughout the Holocene. We reconstructed CH4 emissions from northern peatlands from 13,000 BP to present using an empirical model based on observations of peat initiation (〉3600 dates), peatland type (〉250 peat cores), and observed CH4 emissions in order to explore the effects of changes in wetland type on CH4 emissions over the end of the late glacial and the Holocene. Fen area increased steadily before 8000 BP as fens formed in major wetland complexes. After 8000 BP, new fen formation continued but widespread peatland succession (to bogs) and permafrost aggradation occurred. Reconstructed CH4 emissions from peatlands increased rapidly between 10,600 BP and 6900 BP due to fen formation and expansion. Emissions stabilized after 5000 BP at 42 ± 25 Tg CH4 y-1 as high-emitting fens transitioned to lower-emitting bogs and permafrost peatlands. Widespread permafrost formation in northern peatlands after 1000 BP decreased CH4 emissions by 20% to 34 ± 21 Tg y-1 by the present day and suggests peatland CH4 emissions will increase with permafrost thaw.

Description: The Arctic is greatly impacted by climate change. The increase in air temperature drives the thawing of permafrost and an increase in coastal erosion and river discharge. This leads to a greater input of sediment and organic matter into coastal waters, which substantially impacts the ecosystems by reducing light transmission through the water column and altering the biogeochemistry, but also the subsistence economy of local people, and changes in climate because of the transformation of organic matter into greenhouse gases. Yet, the quantification of suspended sediment in Arctic coastal and nearshore waters remains unsatisfactory due to the absence of dedicated algorithms to resolve the high loads occurring in the close vicinity of the shoreline. In this study we present the Arctic Nearshore Turbidity Algorithm (ANTA), the first reflectance-turbidity relationship specifically targeted towards Arctic nearshore waters that is tuned with in-situ measurements from the nearshore waters of Herschel Island Qikiqtaruk in the western Canadian Arctic. A semi-empirical model was calibrated for several relevant sensors in ocean color remote sensing, including MODIS, Sentinel 3 (OLCI), Landsat 8 (OLI), and Sentinel 2 (MSI), as well as the older Landsat sensors TM and ETM+. The ANTA performed better with Landsat 8 than with Sentinel 2 and Sentinel 3. The application of the ANTA to Sentinel 2 imagery that matches in-situ turbidity samples taken in Adventfjorden, Svalbard, shows transferability to nearshore areas beyond Herschel Island Qikiqtaruk.

Description: Highlights • Coupled geomicrobiology and geomechanics to investigate alterations in shales. • Microbial process can alter the mechanics, mineralogy, and microstructure of shales. • Biogeomechanical alterations reduced permeability by 93% and porosity by 38%. • Microfractures in shales can be sealed during biogeomechanical alterations. • Biogeomechanical alterations can enhance CO2 storage security and caprock integrity. Shales have been a major focus of the energy industry over the past few decades. Recently, there is a paradigm shift in the energy industry to low-carbon solutions, such as carbon capture and storage (CCS), to mitigate global warming caused by carbon footprint. The problem of long-term safe and efficient geological CO2 storage (GCS) and caprock integrity are some of the major challenges impeding large-scale CCS application. Here, we investigated how localized and bulk biogeomechanical alterations could potentially impact caprock integrity and CO2 storage in depleted shale reservoirs. We cultivated the shale core samples (containing both artificial-induced and pre-existing natural fractures) with a cultured microbial solution at specific temperature, time, and growth conditions. Subsequently, we obtain the properties of the fractured shale rock samples impacted by this microbial process. We investigate the impact of the mechanical responses due to the microbial process, on the long-term integrity and storage potentials of CO2 in shale reservoirs. Our results suggest that in Eagle Ford, Marcellus, and Niobrara shale formations, microbially-altered local and bulk mechanical properties can enhance the long-term caprock integrity and CO2 storage security by: (1.) Increasing the localized (+19% unconfined compressive strength, −20% Poisson’s ratio, +35% fracture toughness) and bulk (+50% unconfined compressive strength, −13% Poisson’s ratio) mechanical integrity; (2.) Decreasing permeability (−93%) and porosity (−38%); (3.) Altering the clay mineral content (−56%), calcite content (+21%), and morphology; (4.) Occluding microfractures; and (5.) Mitigating any potential leakage to the atmosphere through the caprock. This study considers the heterogeneity of shales, and provide valuable insights and viable assessment in solving the long-term GCS application in depleted hydrocarbon reservoirs.

Description: In the present work, an untargeted metabolomic approach based on ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC–HRMS) was performed for the discrimination of 25 accessions of white quinoa from main production zones of Peru. From the fingerprint analysis, a total of eighty-four metabolites were tentatively identified based on their accurate mass measurements and MS/MS data. Among them, forty-six compounds are reported here for the first time in C. quinoa (eight phenolics, one ecdysteroid, and thirty-seven saponins), twenty-four of them would correspond to new structures. Principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA) were used to analyze the metabolomic data. As a result, the samples were distributed into two groups. The compounds contributing to the differences between these groups were identified by S-plot analysis.

Description: Highlights • UAV-based thermal imaging allows precise mapping of diffusive thermal water discharge. • High tidal ranges affect fluid flow and promote larger thermal anomaly. • The La Jolla thermal anomaly is caused by a discharge of 330 ± 44 L s−1 of thermal water. • The La Jolla advective heat output (40.5 ± 5.2 MWt) can power a desalinization plant. The exploration of unexploited geothermal resources is required to encourage the use of renewable energy. This study focuses on La Jolla beach, Ensenada, Mexico. The beach hosts a thermal anomaly with temperatures of up to 52 °C at the surface and up to 93 °C at 20 cm depth. The objectives were to: map the thermal anomaly, understand the impact of tides, quantify the thermal water discharge rate and heat output, and discuss a direct use of the energy. The mapping was performed with Unmanned Aerial Vehicles equipped with optical and thermal cameras at two different dates. Additional temperature measurements were performed with a thermocouple, while the total fluid discharge was estimated from flow measurements. A comparison between the campaigns indicated that the highest surface temperature area was more than three times larger in 2019 than in 2018 (259 m2 vs. 69 m2). Such change was due to the tidal range and associated hydrostatic pressure variations. The total thermal water discharge is 330 ± 44 L s−1, which corresponds to an advective heat output of 40.5 ± 5.2 MWt. The use of this energy in a Multi-Effect Distillation desalinization plant can contribute to cover the shortage of freshwater in Ensenada.

Description: The Neolithic Revolution began approximately 10,000 years ago and is characterized by the ultimate, nearly complete transition from hunting and gathering to agricultural food production on land. The Neolithic Revolution is thought to have been catalyzed by a combination of local population pressure, cultural diffusion, property rights and climate change. We undertake a thought experiment that examines trends in these key hypothesized catalysts of the Neolithic Revolution and patterns of today to explore whether society could be on a path towards another paradigm shift in food production: away from hunting of wild fish towards a transition to mostly fish farming. We find similar environmental and cultural pressures have driven the rapid rise of aquaculture, during a period that has now been coined the Blue Revolution, providing impetus for such a transition in coming decades to centuries (as opposed to millennia). However, we also highlight the interacting and often mutually reinforcing impacts of 1) technological and scientific advancements, 2) environmental awareness and collective action and 3) globalization and trade influencing the trajectory and momentum of the Blue Revolution from patterns and processes of the Neolithic Revolution. We present two qualitative narratives that broadly fall within two future trajectories of seafood production: 1) a ubiquitous aquaculture transition and 2) commercial aquaculture and fisheries coexistence. Each narrative contains two sub-narratives based on differing management and regulatory strategies for aquaculture and fisheries. This scenarios approach aims to encourage logical, forward thinking, and innovative solutions to complex systems’ dynamics. Scenario-based thought experiments are useful to explore large scale questions, increase the accessibility to a wider readership, and ideally catalyze discussion around proactive governance mechanisms. We argue the future is not fixed and society now has greater foresight and capacity to choose the workable balance between fisheries and aquaculture that supports economic, environmental, cultural and social objectives through combined planning, policies, and management.

Description: Highlights • Coupled microbiology and geomechanics to investigate alterations in shales. • Microbial process can alter the near-wellbore of shale gas reservoirs. • Microbial alterations of near-wellbore rock properties can weaken mechanical integrity. • Biogeomechanical alterations increased porosity (+42%) & permeability (+6430%). • Biogeomechanical alteration with other stimulation methods can improve gas recovery. Shale gas reservoirs, with typically ultra-low permeabilities, have been a major focus of hydrocarbon production over the past few decades. In this paper, we investigated how biogeomechanical alteration of near-wellbore properties could potentially impact hydrocarbon recovery from low-permeability reservoirs, using Wolfcamp shale and Niobrara shale formations. We first obtained the geomechanical properties using the scratch test method, in addition to the mineralogical, microstructural, and porosity and permeability measurements of the shale gas samples. Subsequently, we treated the core samples with a cultured microbial solution at distinct conditions. Further, we obtained the corresponding new geomechanical properties, in addition to the new mineralogical, microstructural, and porosity measurements of the samples impacted by the process. Finally, we showed the implications of the altered near-wellbore properties for hydrocarbon recovery from shale gas reservoirs. Our results suggest that in shale gas reservoirs, microbial-induced alterations of near well-bore properties could temporally reduce its mechanical integrity (Wolfcamp shale = −21% unconfined compressive strength, −42% scratch toughness; Niobrara shale = −24% unconfined compressive strength, −14% scratch toughness), increase porosity (+43%) and permeability (+6430%), and impact the microstructural and mineralogical properties. The near-wellbore biogeomechanical alterations could potentially improve hydrocarbon recovery by enhancing: (1.) the susceptibility for induced fractures to nucleate and propagate during reservoir-stimulation; (2.) flow pathways to improve hydrocarbon recovery.

Description: Both chemical and isotopic compositions of volcanic plumes are highly useful in evaluating the present status of active volcanoes. Monitoring their temporal changes can facilitate the forecasts of volcanic activity as well. In the present study, we developed a drone-borne automatic sampler for volcanic plumes in which an output signal from a sulfur dioxide (SO2) sensor triggered a pump to collect samples when its SO2 concentration exceeded a predefined threshold. First, we tested the automatic sampler while holding the device by hand at Iwo-yama volcano, Kirishima volcanic complex, Japan, where the fumaroles were accessible. Second, we fitted the sampler on a drone at Nakadake central cone, Aso volcano, Japan, where only the crater rim was accessible. In both sampling campaigns, good consistency in isotope ratios (2H/1H) of molecular hydrogen (H2) between samples collected by the automatic sampler and those collected directly into pre-evacuated flasks was obtained. Furthermore, by using the drone-borne sampler at Aso volcano, we obtained plume samples with higher concentrations of H2 and carbon dioxide than those taken directly into flasks at the crater rim. Our sampler can be utilized to collect volcanic plume samples for the determination of stable isotopic compositions in general by subsequent laboratory analysis and the remote establishment of fumarole outlet temperature based on the 2H/1H ratios of hydrogen, including their temporal changes.

Description: Volcaniclastic stratigraphy can be difficult to map and describe due to its complex nature. However, such stratigraphy preserves information about fluctuations in volcanic activity and sedimentation and is vital to understanding volcanic systems. Uncrewed aerial vehicle (UAV) based analysis of volcanic stratigraphy can enhance mapping and analysis, especially on vertical surfaces where outcrop exposure is greatest. Here we present a method for using small UAVs to produce vertical grain size and bedding measurement logs, or quantitative stratigraphic columns, of vertical volcaniclastic stratigraphy. We demonstrate the range of high-accuracy measurements and parameters that can be collected for building measurement logs using consumer grade UAVs through a case study in the Marysvale volcanic field where we collected 34,422 grain measurements from 21 individual units. The purpose of producing such measurement logs is to enhance lithofacies analysis through the use of large quantitative datasets and improve the reproducibility of data reporting. Whereas descriptions of volcaniclastic units such as those describing grading are often reported qualitatively, we describe methods for calculating numerical parameters for enhanced lithologic analysis including grain size, grading, clast to matrix ratios, and shape characteristics. The methods described in this paper can enhance field data acquisition, mapping, and quantitative analysis of volcaniclastic deposits and are applicable to a wide range of other geologic settings where coarse-grained clastic sedimentary deposits exist.

Description: Highlights: • Temperature anomalies for the Mid-Holocene compared to preindustrial are significantly different in the low- and high-resolution versions of the atmospheric model ECHAM5 • For summer, shortwave cloud radiative forcing emerges as an important factor. • For boreal winter, differences are mainly related to circulation changes. • Anomaly differences are regionally as large as the mid-Holocene minus preindustrial temperature signals. Abstract: This study evaluates the dependence of simulated surface air temperatures on model resolution and orography for the mid-Holocene. Sensitivity experiments with the atmospheric general circulation model ECHAM5 are performed with low (∼3.75°, 19 vertical levels) and high (∼1.1°, 31 vertical levels) resolution. Results are compared to the respective preindustrial runs. It is found that the large-scale temperature anomalies for the mid-Holocene (compared to preindustrial) are significantly different in the low- and high-resolution versions. For boreal winter, differences are mainly related to circulation changes caused by the response to thermal forcing in conjunction with orographic resolution. For summer, shortwave cloud radiative forcing emerges as an important factor. The anomaly differences (low minus high resolution version) in the Northern Hemisphere are regionally as large as the anomalous mid-Holocene temperature signals. Furthermore, they depend on the applied surface boundary conditions. We conclude that the resolution matters for the Northern Hemisphere response in mid-Holocene simulations, which should be taken into account in model-model and data-model comparisons.

Description: Highlights • UAV surveys can be used for evaluating long-term hillslope morphology evolution. • Successive landslides influence frequency distributions of topographic features. • Successive landslides gradually reduce slope gradient, roughness and local relief. • The slope gradient changes with elevation. Landslides are recognized as dominant geomorphic events of morphological evolution in most mountainous and hilly landscapes. However, the lack of multitemporal high-resolution topographic data has resulted in a lack of quantitative estimates of topographic changes influenced by successive landslides. Taking a typical hillslope with successive loess landslides in the Heifangtai loess tableland, China, as an example, we conducted four unmanned aerial system (UAS) surveys and created corresponding high-resolution digital elevation models (HRDEMs) and orthophotos. We found that multitemporal UAS surveys have become a powerful new approach for addressing local topographic changes and evolution over a relatively long time series. Moreover, landslides can leave persistent geomorphic imprints on hillslope topography. The frequency distributions of topographic indexes are significantly influenced by successive landslides. The mean slope gradient, roughness and local relief decreased with successive landslide occurrences, whereas the mean topographic wetness index (TWI) increased. However, the mean slope aspect was almost unchanged by successive landslides. Furthermore, analysis of the coefficient of variation demonstrates that the frequency distribution of the slope gradient becomes more dispersed with landslide occurrences, while the slope aspect and TWI become more concentrated. The slope gradient changes with elevation. More broadly, this study provides new insights into the prediction of the local topographic feature changes and morphology evolution trends caused by successive landslides.

Description: Highlights • Shale samples were exposed to slick water under the condition of 120 °C and 20 MPa within 30–90 days. • Microindentation was conducted to probe the distance-dependent, gradient alteration to shale mechanical properties. • The average rate of softening advancement was estimated as 0.13 mm/day. • The dissolution of carbonate minerals, pyrite oxidation and clay mineral osmotic swelling determine the shale softening. The shale softening behavior caused by hydrofracturing fluid is of great influence for the fracture conductivity and ultimate recovery of oil and gas from reservoir formations. This paper presents an experimental study on the characterization of a shale after being softened by the coupled thermo-hydro-mechanical-chemical (THMC) treatments that simulate the high-temperature and high-pressure rock-fluid interactions occurring in deep reservoirs during and after hydraulic fracturing. Microindentation tests were conducted to characterize the degradation degree and rate of mechanical properties of THMC-treated samples, and X-ray diffraction (XRD), scanning electron microscope (SEM), and micro-computed tomography (micro-CT) were carried out to analyze compositional and microstructural alterations of samples prior to and after THMC treatment. The results show that Young's modulus, hardness, and fracture toughness degrade significantly upon THMC treatment, and the average softening rate was estimated as 0.13 mm/day. The degradation of mechanical properties of the softened zones is primarily owing to the porous microstructure and crack propagation, resulting from the dissolution of carbonates, pyrite oxidation and the clay mineral osmotic swelling. These findings can provide a good insight of shale-fracturing fluid interactions, phenomenological behavior of shale softening that take place in deep reservoirs at elevated temperatures and pressures, and shed lights on the design, and operation of shale gas exploration.

Description: The recent and growing development and availability of unmanned aerial vehicles/systems (UAV, UAS, or “drones”) in volcanology has promoted a significant advance in volcanic surveillance of active volcanoes and in the characterization of volcanic landforms and hazards. However, in the tropics with heavy rainfall, deep volcanic soils and high relief, UAV surveying for volcanic geomorphology and volcanic hazards seems to be a relatively unexplored technique. Our aim is to present and promote innovative low-cost (〈$3000) UAV applications in volcanology to reduce costs and improve high-resolution quality (up to 8 cm/pixel) data acquisition in highly dynamic landscapes. Our results contribute to the state of the art of UAV applications in volcanic landforms in tropical developing countries where nearly half of the globally active volcanoes are located. Our findings prove that UAV's are a low-cost technique that can map large extensions of geomorphological features with accessibility limitations due to geological hazards and/or private property restrictions in short time. We surveyed four active volcanic sites in Costa Rica, Central America to illustrate potential applications of UAV mapping and geomorphological analysis of lava flows, debris avalanches, lahar deposits (debris flows) and biogeomorphic landscape changes due to forest succession. Analysis derived from the digital imagery captured by the UAV allowed to determine accurate volume calculations, surface roughness characteristics, morphometric quantifications, supervised surface classifications, and in combination with hydraulic modelling to assess hazards in urban planning. We discuss the utility, limitations, and future directions of low-cost UAV surveying in the geomorphological and geological analysis of tropical volcanic landforms and processes.

Description: Mount Agung (the highest volcano in Bali, Indonesia) began to erupt on November 21, 2017, after having been dormant for 53 years. More than 100,000 people were evacuated within the hazard zone between September 2017 (when the highest volcanic alert was issued) and early 2018. The eruptions continued until June 2019, accompanied by at least 110 explosions. During the eruptive crisis, the observation of the lava dome's emplacement was essential for mitigating the potential hazard. Details of the lava dome growth, including the volumetric changes and effusion rates, provide valuable information about potential eruption scenarios and lahar depositions. In this paper, the essential role of multi-temporal unmanned aerial vehicle (UAV) images in the monitoring of Mt. Agung's lava dome, and in determining the areas of potential lahar hazards during the crisis between 2017 and 2019 is described. A fixed-wing UAV was launched outside the hazard zone to photograph the lava dome on five occasions. Image enhancement, machine learning, and photogrammetry were combined to improve image quality, remove point clouds outliers, and generate digital terrain models (DTMs) and orthoimages. The analysis of the obtained DTMs and orthoimages resulted in qualitative and quantitative data highlighting the changes inside the crater and on the surrounding slopes. These results reveal that, from November 25 to December 16, 2017, the lava dome grew vertically by 126 m and reached a volume of 26.86 ± 0.64 × 106 m3. In addition, its surface experienced a maximal uplift of approximately 52 m until July 2019 with the emergence of a new dome with a volume estimated at 9.52 ± 0.086 × 106 m3. The difference between the DTMs of 2017 and 2019 reveals the total volume of erupted material (886,100 ± 8000 m3) that was deposited on the surrounding slopes. According to the lahar inundation simulation, the deposited material may cause dangerous lahars in 21 drainages, which extend in the north (N), north-east (N-E), south (S), south-east (S-E), and south-west (S-W) sectors of the volcano. This paper presents the use of UAV remote sensing for the production of high-spatial resolution DTMs, which can be used to both observe the emplacement of a lava dome, and to identify areas with potential lahar risk during a volcano crisis.

Description: Highlights • A new approach using UAS to map and classify volcanic deposits is described. • Tephra and lava are distinguished by their roughness and solar heating rate. • Solar heating rate decreases as lava transitions from pāhoehoe to ʻaʻā. • We compare manual and machine learning classification methods. The deposits from volcanic eruptions represent the record of activity at a volcano. Identification, classification, and interpretation of these deposits are crucial to the understanding of volcanic processes and assessing hazards. However, deposits often cover large areas and can be difficult or dangerous to access, making field mapping hazardous and time-consuming. Remote sensing techniques are often used to map and identify the deposits of volcanic eruptions, though these techniques present their own trade-offs in terms of image resolution, wavelength, and observation frequency. Here, we present a new approach for mapping and classifying volcanic deposits using a multi-sensor unoccupied aerial system (UAS) and demonstrate its application on lava and tephra deposits associated with the 2018 eruption of Sierra Negra volcano (Galápagos Archipelago, Ecuador). We surveyed the study area and collected visible and thermal infrared (TIR) images. We used structure-from-motion photogrammetry to create a digital elevation model (DEM) from the visual images and calculated the solar heating rate of the surface from temperature maps based on the TIR images. We find that the solar heating rate is highest for tephra deposits and lowest for ʻaʻā lava, with pāhoehoe lava having intermediate values. This is consistent with the solar heating rate correlating to the density and particle size of the surface. The solar heating rate for the lava flow also decreases with increasing distance from the vent, consistent with an increase in density as the lava degasses. We combined the surface roughness (calculated from the DEM) and the solar heating rate of the surface to remotely classify tephra deposits and different lava morphologies. We applied both supervised and unsupervised machine learning algorithms. A supervised classification method can replicate the manual classification while the unsupervised method can identify major surface units with no ground truth information. These methods allow for remote mapping and classification at high spatial resolution (〈 1 m) of a variety of volcanic deposits, with potential for application to deposits from other processes (e.g., fluvial, glacial) and deposits on other planetary bodies.

Description: Highlights: • Wind-PV power mix beneficial for balancing variability due to weather. • Ratio of 45–57% for PV over PV plus wind power maximises balancing effects. • Simultaneous extremes in wind and PV power occur on less than 10% of the days. Abstract: The increasing use of wind and solar power requires interventions to balance the associated variability in energy production. One option to reduce the costly interventions is to exploit the natural de-correlation of wind and irradiance. This study characterises the balancing potential of the natual variability in wind and photovoltaic energy production within and across eleven European countries. We use 20 years of highly resolved meteorological data from a post-processed regional reanalysis with a 6 km horizontal grid to calculate daily photovoltaic and wind power. Our results suggest a country-dependent reduction of the day-to-day variability in energy production by 29%–42% due to installing both PV and wind power capacities, compared to wind power only. The optimized photovoltaic to photovoltaic plus wind power generation ratios are 45–57% for maximizing balancing effects associated with the changing weather. We further identify on less than 10% of the days a simultaneous occurrence of extremes in photovoltaic and wind power across European countries. The cross-border balancing potentials for the extremes in renewable energy production are therefore high due to the spatio-temporal differences of the local weather.

Description: Highlights • Shear strength in the BPT is estimated based on tensorial strain partitioning. • Accounting for full strain components resolves problems in the two-mechanism model. • Inclination of slip planes causes weakening relative to the friction law. • Fault-parallel compression is significant in the BPT and brittle regimes. A constitutive law of shear zones in the brittle-plastic transition (BPT) is of great importance to understanding loading at the bottom of the seismogenic layer preceding large earthquakes. Previous microphysics-based models are based on the partitioning of slip and dilation normal to the shear zone into different deformation mechanisms. Here, I account for the remaining 2-D strain component, inelastic extension of the shear zone, and associated stress buildup parallel to the shear zone, and investigate the steady-state behavior of a shear zone in which slip on inclined planes and bulk plastic flow coexist. Kinematic constraints and constitutive laws of the two mechanisms were solved numerically. The results show that the inclination of slip planes causes weakening relative to the friction law. Whereas the previous two-mechanism model yields a larger strength than the friction law for a rate-weakening slip element in the BPT, the present model qualitatively resolves this problem. Fault-parallel compression buildup can exceed the normal stress in the BPT and the brittle regime if the friction coefficient of the slip planes is in the range of Byerlee's law. This study illuminates the importance of fault-parallel compression in understanding the fabrics and strengths of shear zones.

Description: Degassing volcanic systems, expressed by fumaroles, thermal anomalies, and hydrothermal alteration and deposition at the surface provide insights into the underlying structural architecture and the magmatic system. While the fumarole sites are easily identified and investigated, areas of diffuse degassing and associated hydrothermal alteration are barely explored. Here we investigate high-resolution optical and thermal infrared (TIR) data, acquired by unoccupied aircraft systems (UAS) at the La Fossa cone (Vulcano Island) in November 2018. The data provides insights into the structural complexity of degassing sites and associated processes at the surface. Applying the Structure from Motion (SfM) approach, we generate a photomosaic database with a 0.05 m and 0.7 m pixel resolution for the optical and infrared datasets, respectively. A Principal Component Analysis (PCA) was applied to the optical data to detect, define and extract areas of hydrothermal alteration and sulfuric deposition on a pixel base, with a feature detection threshold of up to 25 cm2. By comparing optical data, PCA results and the IR data, we found a broad alteration zone dominated by diffuse degassing surrounding the main fumaroles, which with ~ 60,000 m2 is ten times larger than the area covered by fumaroles and yellowish sulfuric deposits. Spectral and thermal characteristics of this alteration zone suggest a segmentation into at least 13 distinct subregions. Hydrothermal alteration and deposition were analyzed considering their pixel density and spectral signature (RGB) and show the highest pixel density in the center of the fumarole field, accompanied by a systematic color shift. The same region is characterized by a systematic change in azimuths of thermal lineaments and sulfuric clusters from the dominating trend NW-SE by ~90 degrees to NE-SW. We conjecture this to be controlled by a permeability contrast due to a subsurface structure or crater intersection, facilitating a more direct gas ascent in the center of the fumarole field. We provide a precise and complete database for the state and extent of the La Fossa fumarole field, which can be used for comparative monitoring of spatio-temporal changes within the hydrothermal system at the surface.

Description: Highlights • Release of additives from plastic pollution may harm wildlife. • Robust methods to characterise additives and their leaching behaviour are needed. • Extraction and leaching methods are informed from well-established industry methods. • Recommended approaches for extraction and leaching studies are presented. • The use of environmentally relevant methods and test materials is advised. Plastic pollution is prevalent worldwide and has been highlighted as an issue of global concern due to its harmful impacts on wildlife. The extent and mechanism by which plastic pollution effects organisms is poorly understood, especially for microplastics. One proposed mechanism by which plastics may exert a harmful effect is through the leaching of additives. To determine the risk to wildlife, the chemical identity and exposure to additives must be established. However, there are few reports with disparate experimental approaches. In contrast, a breadth of knowledge on additive release from plastics is held within the food, pharmaceutical and medical, construction, and waste management industries. This includes standardised methods to perform migration, extraction, and leaching studies. This review provides an overview of the approaches and methods used to characterise additives and their leaching behaviour from plastic pollution. The limitations of these methods are highlighted and compared with industry standardised approaches. Furthermore, an overview of the analytical strategies for the identification and quantification of additives is presented. This work provides a basis for refining current leaching approaches and analytical methods with a view towards understanding the risk of plastic pollution.

Description: Highlights • Carbon dioxide + propane mixtures are studied through accurate measurements of speeds of sound and phase equilibria. • Heat capacities and virial coefficients are obtained from speeds of sound. • Retrograde condensation zone is found for the (0.60 CO2 + 0.40 C3H8) mixture. • Results are compared with reference equations of state such as GERG-2008 and AGA8-DC92. This work presents phase envelope and speed of sound data for the (0.60 CO2 + 0.40 C3H8) and (0.80 CO2 + 0.20 C3H8) binary mixtures. Phase equilibria was measured using a cylindrical resonator working in the microwave band whereas an acoustic resonator was used for speed of sound measurements. The experimental results were compared with GERG-2008 equation of state, obtaining average absolute deviations by 0.24% in pressure for phase equilibria data and 0.025% for speed of sound data. Speed of sound values were used to derive perfect-gas heat capacities, acoustic virial coefficients, and second density virial coefficients. In addition, AGA8-DC92 equation of state performance was checked for the results derived from speeds of sound.

Description: Most air quality stations in Spain exceeded the European Union's daily PM10 limit due to the February 2016 Saharan dust outbreak, which resulted from two successive dust storms in Northwest Africa. This study identifies the meso-β/meso-γ-scale dynamical processes responsible for developing these dust storms using observations and high-resolution Weather Research and Forecasting model coupled with Chemistry simulations. The results revealed that the first dust storm was associated with a strong barrier jet (BJ). The BJ formed on the southeastern foothills of the Saharan Atlas Mountains (SAM) when an easterly-northeasterly low-level Mediterranean flow was blocked by a stably stratified layer close to the SAM. The BJ intensified just after sunrise on 20 February and the associated near-surface peak winds organized the first dust storm. The second dust storm was linked to a mesoscale gravity wave (MGW) and hydraulic jumps. A long-lived westward propagating MGW was triggered by a downslope flow interacting with the stable layer near the northeastern edge of the Tinrhert Plateau in eastern Algeria. When this MGW crossed the Tademaït Plateau, hydraulic jumps formed on its lee side. The strong winds accompanying these hydraulic jumps formed the second dust storm on 21 February. The lifted dust extended over a depth of 2–3 km in the growing daytime boundary layer and was advected poleward by the southerly/southeasterly mid-tropospheric winds. Our results underline the importance of resolving terrain-induced mesoscale processes to understand dust storm dynamics, which are difficult to represent in coarse-resolution numerical models.

Description: Estimations of the global carbon budget include a quantitative understanding of the evolving processes that occur along river-to-ocean gradients. However, high spatiotemporal resolution observations of these processes are limited. Here we present in situ measurements of the partial pressure of CO2 (pCO2) made through the Amazon River plume (ARP) during different discharge seasons, from 2010 to 2012. We evaluated the spatiotemporal distribution of pCO2 using Soil Moisture and Ocean Salinity (SMOS) satellite observations for each hydrologic period in the ARP. Regression models were used to estimate pCO2 at the ARP for the period of 2010–2014. From these distributions we calculated sea-air gas exchange of CO2 between the plume waters and the atmosphere (Fsea co2). Intra-annual variability of Fsea co2 was related to discharge at the river mouth and ocean currents as well as trade winds in the plume. Climatic events during the study period had a significant impact on the Fsea co2. Including the plume area closer to the river mouth makes the ARP a net source of CO2 with an annual net sea-air flux of 8.6 ± 7.1 Tg C y−1 from 2011 to 2014.

Description: Isocitrate dehydrogenase (IDH) is one key rate-limiting enzyme in the tricarboxylic acid cycle, which is related to various cancers. Tomatillo (Physalis ixocarpa), a special tomato, is widely consumed as nutritious vegetable in Mexico, USA, etc. As a rich source for withanolides, the fruits of P. ixocarpa were investigated, leading to the isolation of 11 type-A withanolides including 4 new ones (1 is an artificial withanolide). All these withanolides were evaluated for their inhibition on mutant IDH1 enzyme activity. Among them, physalin F (11) exhibited potent enzyme inhibitory activity and binding affinity with mutant IDH1. It inhibits the proliferation of HT1080 cells by selectively inhibiting the activity of mutant IDH1. Since Ixocarpalactone A, another major type-B withanolide in this plant, could act on another energy metabolism target PHGDH, the presence of different types of withanolides in tomatillo and their synergistic effect could make it a potential antitumor functional food or drug.

Description: often recognized too late, typically when changing the adopted technologies and behavioral norms is difficult. A similar story may unfold if society continues to blindly transition to an unregulated and environmentally unaudited digital world, a transition path that has been facilitated by the fourth industrial revolution and is now accelerated by the global COVID-19 crisis. The newly developed digital lifestyle has major environmental benefits, including the reduction of travel-related CO2 emissions. Yet, increased Internet use has some hidden environmental impacts that must be uncovered (Fig. 1a) to make the transition to a lowcarbon and green economy successful. The data centers’ electricity consumption accounts for 1% of the global energy demand (Masanet et al., 2020), more than the national energy consumption of many countries. Depending on the energy supply mix and use efficiency, Internet traffic contributes differently to negative environmental impacts and climate change. As the number of Internet users increases, the number of online services and applications they use grow. This trend exacerbates the environmental footprint of the Internet, despite the many successful and significant efforts to improve the efficiency of data centers (Masanet et al., 2020) and reduce their reliance on fossil energy. In order to build a sustainable digital world, it is imperative to carefully assess the environmental footprints of the Internet and identify the individual and collective actions that most affect its growth.

Description: Fucus virsoides and Cystoseira barbata are important sources of sulfated polysaccharide fucoidan which shows a wide range of biological activities. These activities are significantly dependent on chemical composition which is influenced by species, anatomical part of the seaweed, growing location and conditions, extraction procedures and analytical methods. The objective of this study was to evaluate influence of various pre-treatment solvents and conventional extraction parameters (solvent, temperature and time) on polysaccharide yield and chemical composition (total sugar, fucose, sulfate group and uronic acid content) of the fucoidan from F. virsoides and C. barbata. Combination of acetone and ethanol was chosen for pre-treatment since it removed the most interfering compounds and resulted with the highest polysaccharide yield. Applying acid (0.1 M HCl and 0.1 M H2SO4) instead of water for polysaccharide extraction improved yield and resulted with fucoidan with higher sulfate group content, lower uronic acid content but lower fucose content. Extraction at higher temperatures and longer time resulted with higher polysaccharide yield, uronic acid and total sugars content. However, they had the opposite effect on fucose and sulfate group content between F. virsoides and C. barbata.

Description: Background Glioblastoma multiforme (GBM) is the most frequent, lethal and aggressive tumour of the central nervous system in adults. The discovery of novel anti-GBM agents based on the isocitrate dehydrogenase (IDH) mutant phenotypes and classifications have attracted comprehensive attention. Purpose Diterpenoids are a class of naturally occurring 20-carbon isoprenoid compounds, and have previously been shown to possess high cytotoxicity for a variety of human tumours in many scientific reports. In the present study, 31 cassane diterpenoids of four types, namely, butanolide lactone cassane diterpenoids (I) (1-10), tricyclic cassane diterpenoids (II) (11-15), polyoxybutanolide lactone cassane diterpenoids (III) (16-23), and fused furan ring cassane diterpenoids (IV) (24-31), were tested for their anti-glioblastoma activity and mechanism underlying based on IDH1 mutant phenotypes of primary GBM cell cultures and human oligodendroglioma (HOG) cell lines. Results We confirmed that tricyclic-type (II) and compound 13 (Caesalpin A, CSA) showed the best anti-neoplastic potencies in IDH1 mutant glioma cells compared with the other types and compounds. Furthermore, the structure-relationship analysis indicated that the carbonyl group at C-12 and an α, β-unsaturated ketone unit fundamentally contributed to enhancing the anti-glioma activity. Studies investigating the mechanism demonstrated that CSA induced oxidative stress via causing glutathione reduction and NOS activation by negatively regulating glutaminase (GLS), which proved to be highly dependent on IDH mutant type glioblastoma. Finally, GLS overexpression reversed the CSA-induced anti-glioma effects in vitro and in vivo, which indicated that the reduction of GLS contributed to the CSA-induced proliferation inhibition and apoptosis in HOG-IDH1-mu cells. Conclusion Therefore, the present results demonstrated that compared with other diterpenoids, tricyclic-type diterpenoids could be a targeted drug candidate for the treatment of secondary IDH1 mutant type glioblastoma through negatively regulating GLS.

Description: Some trace elements (TE) are eminently toxic for humans (e.g., Al, Pb, Hg, Cd) and its presence in the central nervous system has been linked to the etiology of neurodegenerative diseases (ND). More recently, the focus has shifted to the potential role of the imbalances on essential TE levels (e.g., Fe, Cu, Zn, Se) within the brain tissue, and they have also been identified as potentially responsible for the cognitive decline associated with normal ageing and the development of some ND, although their definite role remains unclear. Accurately, well-defined reference values for TE levels in human body fluids and tissues are indispensable to identify possible disturbances in individual cases. Moreover, since the brain is a highly heterogeneous organ, with anatomically and physiologically very different areas, a detailed mapping of TE distribution across the brain tissue of normal individuals, with an in-depth analysis of TE levels in the different brain regions, is a mandatory prior work so that the results obtained from patients suffering from ND and other brain diseases can be interpreted. This review aims to compile and summarize the available data regarding TE levels in the different human brain regions of “normal” (non-diseased) individuals in order to contribute to the establishment of robust reference values. Fifty-four studies, published since 1960, were considered. The results showed a great variability between different studies. The potential sources of this variability are discussed. The need for increased harmonization of experimental strategies is highlighted in order to improve the comparability of the data obtained.

Description: Highlights: • Ecological impacts of Pontogammarus maeoticus increased with temperature • Salinity effects were non-significant across temperatures (14–2 ppt; 18–22 °C) • Gammarids displayed hyperbolic Type II functional responses in all treatments • Future salinity regime shifts will not lessen ecological impacts via predation • Warming will heighten the ecological impacts of this emerging invasive species Abstract: Biological invasions are a growing ecological and socioeconomic problem worldwide. While robust predictions of impactful future invaders are urgently needed, understandings of invader impacts have been challenged by context-dependencies. In aquatic systems in particular, future climate change could alter the impacts of invasive non-native species. Widespread warming coupled with sea freshening may exacerbate ecological impacts of invaders in marine environments, compromising ecosystem structure, function and stability. We examined how multiple abiotic changes affect the potential ecological impact of an emerging invasive non-native species from the Ponto-Caspian region — a notorious origin hotspot for invaders, characterised by high salinity and temperature variation. Using a comparative functional response (feeding rates across prey densities) approach, the potential ecological impacts of the gammarid Pontogammarus maeoticus towards native chironomid prey were examined across a range of current and future temperature (18, 22°C) and salinity (14, 10, 6, 2 ppt) regimes in a factorial design. Feeding rates of P. maeoticus on prey significantly increased with temperature (by 60 %), but were not significantly affected by salinity regime. Gammarids displayed significant Type II functional responses, with attack rates not significantly affected by warming across all salinities. Handling times were, however, shortened by warming, and thus maximum feeding rates significantly increased, irrespective of salinity regime. Functional responses were significantly different following warming at high prey densities under all salinities, except under the ambient 10 ppt. Euryhalinity of invasive non-native species from the Ponto-Caspian region thus could allow sustained ecological impacts across a range of salinity regimes. These results corroborate high invasion success and field impacts of Ponto-Caspian gammarids in brackish through to freshwater ecosystems. Climate warming will likely worsen the potential ecological impact of P. maeoticus. With invasions growing worldwide, quantifications of how combined elements of climate change will alter the impacts of emerging invasive non-native species are needed.

Description: Highlights: • Predators displayed a Type II functional response towards prey • Microplastics had no effect on predator feeding efficiency • Functional responses are a useful tool for microplastic exposure studies • An environmentally relevant approach is needed in future microplastic exposure studies Abstract: Microplastics may affect the physiology, behaviour and populations of aquatic and terrestrial fauna through many mechanisms, such as direct consumption and sensory disruption. However, the majority of experimental studies have employed questionably high dosages of microplastics that have little environmental relevance. Predation, in particular, is a key trophic interaction that structures populations and communities and influences ecosystem functioning, but rarely features in microplastic research. Here, we quantify the effects of low (~65-114 MP/L) and high (~650-1140 MP/L) microplastic concentrations on the feeding behaviour of a ubiquitous and globally representative key marine predator, the shore crab, Carcinus maenas. We used a functional response approach (predator consumption across prey densities) to determine crab consumption rates towards a key marine community prey species, the blue mussel Mytilus edulis, under low and high microplastic concentrations with acute (8h) and chronic (120 h) microplastic exposure times. For both the acute and chronic microplastic exposure experiments, proportional prey consumption by crabs did not differ with respect to microplastic concentration, but significantly decreased over increasing prey densities. The crabs thus displayed classical, hyperbolic Type II functional responses in all experimental groups, characterised by high consumption rates at low prey densities. Crab attack rates, handling times and maximum feeding rates (ie functional response curves) were not significantly altered under lower or higher microplastics concentrations, or by acute or chronic microplastic exposures. Here, we show that functional response analyses could be widely employed to ascertain microplastic impacts on consumer-resource interactions. Furthermore, we suggest that future studies should adopt both acute and chronic microplastic exposure regimes, using environmentally-relevant microplastic dosages and types as well as elevated future scenarios of microplastic concentrations.

Description: The facies distribution in time and space of sedimentary successions is controlled by a complex interplay between physical, chemical and biological processes, which are nowadays difficult to construe from the geological record. Numerical models constitute a valuable tool to identify and quantify such controlling factors permitting a reliable 3D extrapolation and prediction of stratigraphic and facies architectures beyond outcropping rock strata. This study assesses the roles of three controlling parameters being carbonate production rate, relative sea-level changes and terrigenous clastic sediment supply, on the evolution of an Aptian carbonate system. The SIMSAFADIM-CLASTIC, a 3D process-based sedimentary-stratigraphic forward model, was used for this evaluation. The carbonate succession modelled crops out in the western Maestrat Basin (E Iberia), and corresponded to a platform-to-basin transition comprising three depositional environment-related facies assemblages: platform top, slope and basin. Testing of geological parameters in forward modelling results in a wide range of possible 3D geological scenarios. The documented distribution of facies and sequence-stratigraphic framework combined with a virtual outcrop model were used as a reference to perform geometric (quantitative) and architectural and stacking pattern (qualitative) research by model-data comparison. The time interval modelled spans 1450 ky. The best-fit simulation run characterizes and quantifies (1) relative sea-level fluctuations recording five different genetic types of deposit (systems tracts) belonging to two depositional sequences as expected from field-data analysis, (2) a rate of terrigenous clastic sediment input ranging between 0.5 and 2.5 gr/s, and (3) a mean autochthonous carbonate production maximum rate of 0.08 m/ky. Furthermore, the quantitative and qualitative sensitivity tests carried out highlight that the fluctuation of relative sea level exerted the main control on the resulting stratigraphic and facies architectures, whereas the effect of inflowing terrigenous clastic sediment is less pronounced. Facies assemblages show different sensitivities to each parameter, being the slope carbonates more sensitive than the platform top facies to inflowing fine terrigenous sediments. On slope depositional settings, siliciclastic input also controls stratal stacking patterns and the dimensions of the carbonate bodies formed. The final 3D model allows to spot architectural features such as stacking patterns that can be misinterpreted by looking at the resulting record in the outcrop or by using other 2D approaches, and facilitates the comprehension of reservoir connectivity highlighting the occurrence of initial disconnected regressive platforms, which were later connected during a transgressive stage.

Description: Highlights: • The pivot point for sea level shifted to the west of the Nino4 region in the 2000s. • This enabled the thermocline feedback to increase strongly in the Central Pacific. • The resulting increase in CP events maintains the pivot point to the west, a positive feedback mechanism. Monthly mean sea level variations computed using a linear, reduced-gravity, multi-mode model are combined with satellite measurements to explore why Central Pacific (CP) ENSO events occur more frequently since 2000s. The pivot point for sea level (and hence thermocline) variations has shifted westward in response to an increase in zonal wind stress variance in the western equatorial Pacific. As a result, the Nino4 region is increasingly to the east of the pivot point enabling the thermocline feedback to operate there, strengthening the Bjerknes feedback mechanism in the Nino4 region and leading to an increase in the occurrence of CP events. The increased variance of wind stress in the western Pacific is, in turn, caused by the resulting increase in the frequency of CP events. These arguments imply a positive feedback in which CP events are self-maintaining and suggest that they may be part of the natural variability of the climate system and could occur without the need for changes in external forcing.

Description: In situ pumps were used to collect size-fractionated particles (〉53 μm and 1–53 μm) from the upper ocean of the high latitude North Atlantic during spring and summer 2010, and samples were subsequently analysed for Al, P, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba and Pb. Two research cruises during May 2010 coincided with an eruption of the Eyjafjallajökull volcano in southern Iceland, which resulted in widespread dispersal of ash over the region. Ash deposition caused a noticeable perturbation of particulate trace element concentrations and content within marine particles in the Iceland Basin, relative to the Irminger Basin, most evident for lithogenic elements (Al, Ti, Fe), but also noticeable in elemental ratios for the other elements. The initial volcanic ash influence had largely disappeared by the third research cruise in July/August 2010, although there was evidence for a recent wind erosion event having transported remobilized volcanic ash from southern Iceland to the northern Iceland Basin in early July, further perturbing local trace element biogeochemistry. During summer 2010, concentrations of all measured elements except Ba were typically lower 10 m beneath the surface mixed layer relative to those within it, driven primarily by a rapid decrease in the concentrations of large (〉53 μm) biogenic particles. Depth-dependent trends were more variable over the next hundred metres for all elements except the biogenic elements P and Cd, for which concentrations decreased further. The continued loss of biogenic material with depth due to remineralization (reflected by particulate P concentrations) led to an increase in content per mass of material for all other elements measured. The observed differences in upper ocean particulate P and Fe distributions highlight the mechanism driving seasonal Fe limitation in the high latitude North Atlantic: rapid loss of P by remineralization regenerates dissolved phosphate close to the base of the mixed layer, while most particulate Fe persists deeper in the water column, removing the potential for resupply of dissolved Fe to surface waters.

Description: Highlights • In-situ temperature measurements were conducted at the Danube deep sea fan. • Operations were performed with the MARUM-MeBo200 seafloor drill rig. • The BSR is located ∼20 m below the current gas hydrate stability zone. • Seismic data suggest presence of shallower BSR-like events. Abstract Coring, geophysical logging, and in-situ temperature measurements were performed with the MARUM-MeBo200 seafloor rig to characterize gas hydrate occurrences in sediments of the Danube deep sea fan, off Romania, Black Sea. The new drilling data showed no evidence for significant gas hydrate saturations within the sediments but the presence of free gas at the depth of the bottom-simulating reflector (BSR). In-situ temperature and core-derived geochemical data suggest that the current base of the gas hydrate stability zone (BGHSZ) is ∼20 m shallower than the BSR. Investigation of the seismic data around the drill sites shows several locations where free gas previously trapped at a former BGHSZ migrated upwards forming a new reflection above the BSR. This shows that the gas hydrate system in the Danube deep sea fan is still responding to climate changes initiated at the end of the last glacial maximum.

Description: Body condition and energy reserves are important indicators of organism health, habitat suitability and predictors for the reproductive success in fish. In Greenland waters, Atlantic cod (Gadus morhua) inhabits different habitats in shallow and deep parts on top of the shelf and along slopes, where diet composition differs. We investigated the influence of habitat heterogeneity and trophic niche on body condition using organosomatic indicators, e.g. the morphometric index K, hepatosomatic and gonadosomatic indices, and biochemical indicators, e.g. lipid content and fatty acid compositions, of mature female cod. Body condition differed between sites and peaked in north-eastern regions in depths below 300 m towards the slope of the northern Irminger Sea. Trophic niches as indicated by stable isotope values and stomach composition data varied between sites, which was likely related to depth and differences between benthic and pelagic feeding regimes. Total lipid content and fatty acid profiles important for reproduction were associated with a pelagic diet comprised of mesopelagic fish and crustaceans. Interestingly, consumption of capelin was not linked to highest energy reserves as indicated by traditional body condition indices, such as K and the hepatosomatic index, but lowest ratios of eicosapentaenoic acid to arachidonic acid in gonads, which are known to be beneficial for high egg production. This shows that body condition on biochemical level can differ from conventionally used indices, which emphasizes the need to take fatty acid composition into account, when investigating condition and reproductive potential in cod. Our results emphasize that the factor habitat cannot be ignored for population replenishment of the cod stocks in Greenland waters and indicate that capelin as part of an Arcto-boreal diet benefits reproductive success in cod.

Description: Seagrass meadows are globally recognized as important coastal habitats due to the various ecological functions and ecosystem services they provide. Substantial global decline of seagrass habitats has been recorded over the last decades, underlining the need for extensive studies, including monitoring and mapping these habitats across their distributional range. Cymodocea nodosa (Ucria) Ascherson is the only seagrass species reported in the archipelago of Madeira (NE Atlantic) and systematic or reliable information of its occurrence is very scarce and mostly anecdotal. This study reports the discovery of a yearly-persistent patch of C. nodosa in the southeast coast of Madeira and provides insights into key ecological and biological aspects (e.g. density, leaf length, associated fauna and flora). Seasonal monitoring surveys over a 3-year period, indicate that (1) the patch has increased in size and shoot density over the study period, and (2) leaf lengths follow a typical seasonal pattern over the year. Accounts of past destruction of seagrass meadows in the island, underline the importance of continuous monitoring of the patch and adjacent areas to reveal how the current seagrass patch develops (i.e. patch continuity and/or disappearance), if it integrates a larger meadow and whether anthropogenic pressures as coastal development and/or associated terrigenous sediment runoff events will affect its resilience.