Heat and SO2 Emission Rates at Active Volcanoes – The Case Study of Masaya, Nicaragua

The necessity of understanding volcanic phenomena, so as to assist hazard assessment and risk management, has led to development of a number of techniques for the tracking of volcanic events so as to support forecasting efforts. Since 1980s scientific community has progressively drifted research and surveillance at active volcanoes by integrated approach. Nowadays, volcano observatories over the world record and integrate real or near-real time data for monitoring and understanding volcano behaviour. Among the geophysical, geochemical, and volcanological parameters, the tracking of temperature changes at several volcanic features (e.g., open-vent systems, eruptive vents, fumaroles) and variations in sulphur dioxide flux and concentration at volcanic plumes are key factors for studying and monitoring active volcanoes. Temperature is one of the first parameters that have been considered in understanding the nature of volcanoes and their eruptions. Thermal anomalies have proved to be precursors of a number of eruptive events, and once an eruption begins, temperature plays a major role in lava flow emplacement and lava field development. At active volcanoes, temperature has been measured by direct and indirect methodologies. Direct measurements represent the traditional thermal monitoring carried out at fumaroles, hot springs, molten lava bodies, and crater lakes, using thermocouples. Indirect measurements, also known as thermal remote sensing, can be performed by satellite, ground, and airborne surveys. Owing to the danger of most kinds of eruption, and the need of monitoring inaccessible areas on volcanoes, indirect measurements are especially attractive. Among them, thermal imagery is the most widespread and results from the capability to detect the infrared radiation emitted from the surface of hot bodies, and to provide the radiometric map of heat distribution of the body’s surface. This has been of primary importance for capturing the evolution of thermal anomalies, which shed light on magma movements at shallow depths. While magma is rising, hot gases separate from the melt and escape either directly from the main conduits, or indirectly by leaking through fumaroles, fractures, and faults, or by dissolving within crater lakes and hot spring waters, resulting in variations in their temperature and chemical composition. At the surface, these phenomena are also associated with radiative heat fluxes, which can be detected by infrared thermal detectors. The application of thermal imaging to volcanology was largely performed using satellite surveys, but in the last decade there has been increasing application of compact (hand-held or tripod-mounted) thermal imagers used from the air or ground. Volcanic degassing plays a key role in magma transport and style, and timing of volcanic eruptions observed at the Earth’s surface. The assessment of volcanic gas composition and flux has become a standard procedure for volcanic monitoring and forecasting since degassing regimes are fundamentally linked to volcanic processes. Magma contains dissolved gases that are released into the atmosphere during both quiescent and eruptive stages. At high pressures, deep beneath the Earth’s surface, gases are dissolved in magma; however as soon as magma rises toward the surface, where pressures are lower, gases start to exsolve according to the solubility-pressure relationship of each species, as well as compositional and diffusional constraints. The abundance and final gas phase composition of the emitted plume depends on magma composition(s), volatile fugacities, crystallisation and on the dynamics of magma degassing, including kinetic effects. However, at the surface, the composition and flux of volcanic gases may change with time, reflecting variations in the magmatic feeding system of the volcano. Hence by studying and tracking this variability a number of parameters, such as magma residing depths and the amount of degassing magma bodies can be determined. Among the volcanic gas species, sulphur dioxide (SO2) is one of the most-well investigated in remote sensing. As for temperature, SO2 concentration and emission rates can be measured using both direct sampling and non-contact, remote sensing measurements. The latter carried out during air- and ground-based surveys and satellite platforms, are based on optical spectroscopy. Since the 1970s, SO2 flux has been remotely measured using the COrrelation SPECtrometer (COSPEC) at several volcanoes worldwide. Over the last 10 years the advent of small, commercial and low cost spectrometers offered a valuable replacement to the outdated COSPEC. In particular, the combination of UV spectrometers with the Differential Optical Absorption Spectroscopy (DOAS) analytical method improved significantly data collection offering a number of advantages such as the possibility of obtaining measurements in the challenging environments typical of volcanic areas and detection of other plume species. Our intent here is to discuss findings and implications arising from the integration of thermal imaging-derived temperature and SO2 emission rates. Calibrated temperatures from thermal imagery can provide qualitative as well as quantitative information, fundamental insights and parameters contributing to understanding and modelling of several eruptive features. Anomalies in SO2 emission rates have been often documented at several volcanoes prior to eruptive crisis. In syn-eruptive stages, anomalies in the SO2 flux pattern might indicate variations in the eruptive style and regime associated with changes in the volcano shallow feeder system. At open-vent systems, in non-eruptive phases, changes in SO2 flux emission have provided information on increases or decreases of magma supply in the shallow plumbing system suggesting likely volcanic unrests or magma migration towards peripheral areas of the volcano edifice, respectively. There is still much to explore about volcano behaviour and eruptive mechanisms, however, the combination of different types of monitoring techniques is crucial for constraining baselines for predicting phases of volcano unrests and for gaining useful insights for volcano hazard assessment

Approccio alla caratterizzazione di un lembo di bosco vetusto: il caso di Monte Egitto

An integrated approach to characterize an old growth forest patch; the Monte Egitto case study Old growth forests, i.e. forests which have achieved a remarkable age without or with a very limited disturbance, are nowadays subject of detailed studies in order to understand their characters and capacity of ecosystems services providing. In Sicily only few wooded areas are classified as old growth forest, following the heavy land use change toward agriculture during the centuries. This paper reports the results of a study carried out to characterize the vegetation of a little crater on the Mount Etna, where a residual open wood of Quercus congesta (an endemic oak of Southern Italy) survived the year 1651 lava flows surrounding the crater. About 35 years ago inside the crater some areas were planted with Calabrian Black Pine. As a consequence today there is a remarkable competition between trees of the two species. An integrated approach monitoring was adopted, taking into account both trees and understory (herbs, shrubs and tree regeneration) characters as well as bird fauna, in order to describe the current situation and monitor the effect of pine plantation thinning aimed at favouring oak regeneration and reducing pine-oak competition

The endemic vascular flora of Peloritani Mountains (NE Sicily): Plant functional traits and phytogeographical relationships in the most isolated and fragmentary micro-plate of the Alpine orogeny

This study is aimed at (1) producing a complete and updated inventory of the endemic vascular flora of Peloritani Mountains, (2) defining the geographical limits of Peloritani, regarded here as a biogeographical district and (3) highlighting possible paleogeographic connections with other Mediterranean lands. The heterogeneity analysis of the endemic flora was performed by means of contingency tables, through the x 2 test. The endemic flora of this area consists of 129 specific and infraspecific taxa, of which 15 are restricted to the Peloritani Mountains. The analysis of habitats revealed that endemic taxa are most abundant on cliffs, rangelands, woods and garrigues. A large number of surveyed taxa are endemic to central-southern Italy and Sicily, while the number of endemic taxa in common with Calabria, Etna and Aeolian Islands turned out to be rather low, in spite of the geographical proximity. The endemic flora of Peloritani allows to emphasize palaeogeographical relationships not only with the neighbouring Mediterranean territories, but also with currently remote ones, such as southern Spain, Sardinia and Corsica. The phytogeographical framework substantiates the hypothesis that the Peloritani floristic district coincides with the limit given to Peloritani Mountains by structural geologists

Improved glucose tolerance in mice receiving intraperitoneal transplantation of normal fat tissue

Aims/hypothesis: The association between increased (visceral) fat mass, insulin resistance and type 2 diabetes mellitus is well known. Yet, it is unclear whether the mere increase in intra-abdominal fat mass, or rather functional alterations in fat tissue in obesity contribute to the development of insulin resistance in obese patients. Here we attempted to isolate the metabolic effect of increased fat mass by fat tissue transplantation. Methods: Epididymal fat pads were removed from male C57Bl6/J mice and transplanted intraperitoneally into male littermates (recipients), increasing the combined perigonadal fat mass by 50% (p < 0.005). At 4 and 8weeks post-transplantation, glucose and insulin tolerance tests were performed, and insulin, NEFA and adipokines measured. Results: Circulating levels of NEFA, adiponectin and leptin were not significantly different between transplanted and sham-operated control mice, while results of the postprandial insulin tolerance test were similar between the two groups. In contrast, under fasting conditions, the mere increase in intra-abdominal fat mass resulted in decreased plasma glucose levels (6.9 ± 0.4 vs 8.1 ± 0.3mmol/l, p = 0.03) and a ∼20% lower AUC in the glucose tolerance test (p = 0.02) in transplanted mice. Homeostasis model assessment of insulin resistance (HOMA-IR) was 4.1 ± 0.4 in transplanted mice (vs 6.2 ± 0.7 in sham-operated controls) (p = 0.02), suggesting improved insulin sensitivity. Linear regression modelling revealed that while total body weight positively correlated, as expected, with HOMA-IR (β: 0.728, p = 0.006), higher transplanted fat mass correlated with lower HOMA-IR (β: −0.505, p = 0.031). Conclusions/interpretation: Increasing intra-abdominal fat mass by transplantation of fat from normal mice improved, rather than impaired, fasting glucose tolerance and insulin sensitivity, achieving an effect opposite to the expected metabolic consequence of increased visceral fat in obesit

Bioclimatology, structure, and conservation perspectives of Quercus pyrenaica, Acer opalus subsp. Granatensis, and Corylus avellana deciduous forests on Mediterranean bioclimate in the South-Central part of the Iberian Peninsula

The plant variability in the southern Iberian Peninsula consists of around 3500 different taxa due to its high bioclimatic, geographic, and geological diversity. The deciduous forests in the southern Iberian Peninsula are located in regions with topographies and specific bioclimatic conditions that allow for the survival of taxa that are typical of cooler and wetter bioclimatic regions and therefore represent the relict evidence of colder and more humid paleoclimatic conditions. The floristic composition of 421 samples of deciduous forests in the south-central part of the Iberian Peninsula were analyzed. The ecological importance index (IVI) was calculated, where the most important tree species were Quercuspyrenaica, Aceropalus subsp. Granatensis, and Corylusavellana. These species are uncommon in the south-central part of the Iberian Peninsula, forming forests of little extension. An analysis of the vertical distribution of the species (stratum) shows that the majority of the species of stratum 3 (hemicriptophics, camephytes, geophites, and nanophanerophytes) are characteristic of deciduous forests, and their presence is positively correlated with high values of bioclimatic variables related to humidity and presence of water in the soil (nemoral environments), while they are negatively correlated with high values of bioclimatic variables related to high temperatures, evapotranspiration, and aridity. This work demonstrates that several characteristic deciduous forest taxa are more vulnerable to disappearance due to the loss of their nemoral conditions caused by gaps in the tree or shrub canopy. These gaps lead to an increase in evapotranspiration, excess insolation, and a consequent loss of water and humidity in the microclimatic conditions.info:eu-repo/semantics/publishedVersio

Close-to-Nature Silviculture to Maintain a Relict Population of White Oak on Etna Volcano (Sicily, Italy): Preliminary Results of a Peculiar Case Study

Habitat loss is a potential long-term effect of projected climate change for Mediterranean forest ecosystems. Here, we investigated the effectiveness of a close-to-nature silvicultural practice to conserve an old-growth white oak forest patch in Sicily (Italy) and promote regeneration dynamics. The study area, although small, is distinctive for its isolation, position and environmental characteristics. We conducted a Before-After Control-Impact (BACI) study to analyse the responses of different taxonomic groups (vascular plants and birds) to silvicultural treatments (selection thinning, no thinning), and to determine whether close-to-nature silviculture practices may cause significant shifts in the investigated communities. Specifically, we assessed the responses of (1) vascular plants by means of species diversity and taxonomic distinctness indices and (2) birds in terms of diversity, abundance and forest specialisation. Preliminary results suggest that cautious close-to-nature silviculture practice could-by mimicking natural gap dynamics-contribute to maintaining old-growth forest patches and promote oak seedling emergence without short-term detrimental impacts on biodiversity. Although the monitoring has to be repeated over the long-term, the multi-taxon approach and indices incorporating information on taxonomic relationships into diversity measures were demonstrated to be valuable tools for interpreting biotic community structure and dynamics

Installazione di un radiometro nell'area sommitale del vulcano Etna

Le tecniche di telerilevamento satellitare e da terra per la stima della temperatura di anomalie termiche delle superfici vulcaniche, della loro variazione nel tempo e per individuare attività parossistiche o l’inizio di una fase di colate di lava, sono ormai entrate a far parte della sorveglianza e del monitoraggio vulcanologico [es. Francis, 1979; Geraci et al., 1985; Lombardo et al., 2011; Spampinato et al., 2011]. I sensori in una banda spettrale dell’infrarosso quali radiometri e telecamere termiche, utilizzati in prossimità di bocche eruttive, hanno fornito cospicue quantità di dati di temperatura della superficie di corpi magmatici (colate laviche, laghi di lava, duomi lavici), plume vulcanici, fumarole, registrati a distanza di totale sicurezza [Spampinato et al., 2011]. In particolare, i radiometri, sia portatili che installati in stazioni permanenti, oltre che fornire dati da confrontare con misure geochimiche, permettono l’acquisizione di dati di temperatura ad elevata frequenza, tali da essere messi in relazione con le misure derivate da osservazioni geofisiche quali ad esempio il tremore sismico [es. Harris e Ripepe, 2007; Branan et al., 2008].In questo lavoro si descrivono i dettagli dell’installazione di una stazione radiometrica collocata nell’area sommitale dell’Etna in zona Belvedere, nel sito già utilizzato da una stazione multiparametrica (con sensori sismici e infrasonici) e denominato EBEL. Si descrivono anche la metodologia di trasmissione dati in continuo, il trattamento del dato convertito in temperatura apparente nel campo di vista del radiometro, la visualizzazione in tempo quasi reale del dato e la sua diffusione tramite WEB