Search

In this work, we highlight and measure the intensity of mechanochemical effects at work in the hydrogenation of carbon monoxide by comparing the activity of a supported Co–Fe catalyst subjected, respectively, to ball milling and simple powder agitation. Paying due regard to the discontinuous nature of ball milling, we show that mechanochemical hydrogenation proceeds at significantly higher rate and disclose its connection with individual impacts. Experimental evidence suggests that the enhanced catalytic activity we observe can be ascribed to local processes affecting the amount of powder that gets involved in individual impacts.

Starting from 1970s, the use of mechanical forces to induce chemical transformations has radically changed vast areas of metallurgy and materials science. More recently, mechanochemistry has expanded to core sectors of chemistry, showing the promise to deeply innovate chemical industry while enhancing its sustainability and competitiveness. We are still far, however, from unveiling the full potential of mechanical activation. This study marks a step forward in this direction focusing on the chemical effects induced on the surrounding gaseous phase by the mechanical processing of granite. We show that fracturing granite blocks in oxygen can result in the generation of ozone. The refinement of coarse granite particles and the friction between fine ones are also effective in this regard. Combining experimental evidence related to the crushing of large granite samples by uniaxial compression and the ball milling of coarse and fine granite powders, we develop a model that relates mechanochemical ozone generation to the surface area effectively affected by fracture and frictional events taking place during individual impacts. We also extend the investigation to gaseous phases involving methane, oxygen, benzene and water, revealing that chemical transformations occur as well.

This work focuses on the erodent capability of yttria-stabilized zirconia beads impacting on a limestone target surface. The target surface was used as the cap of a hardened steel vial clamped on a SPEX Mixer/Mill 8000. The vial three-dimensional swing results in repeated bead impacts that cause the material removal from the target surface. The mass loss varies linearly with the number of beads, which allowed estimating the mass lost per bead per impact. It amounts approximately to 70 ng, a value that compares fairly well with the one of about 80 ng estimated from the volume of the indents left on the target surface by individual impacts. Experimental findings indicate that the methodology developed can be reliably utilized to investigate solid particle erosion under highly reproducible and controllable experimental conditions.

Organic solar cells have the potential to become the cheapest form of electricity. Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors. Next generation photovoltaics based upon environmentally benign “green solvent” processing of organic semiconductors promise a step-change in the adaptability and versatility of solar technologies and promote sustainable development. However, high-performing OSCs are still processed by halogenated (non-environmentally friendly) solvents, so hindering their large-scale manufacture. In this perspective, we discuss the recent progress in developing highly efficient OSCs processed from eco-compatible solvents, and highlight research challenges that should be addressed for the future development of high power conversion efficiencies devices.

Over the past 15 years several expeditions by French, American and especially Italian cavers have unveiled over 50 caves in the Cordillera de la Sal (Atacama Desert, Northern Chile). Many of these caves contain a variety of speleothems and minerals, some of which have rarely been observed within karst systems. Most of the secondary deposits in these caves are composed of halite, but also other halide, carbonate, sulphate, nitrate, phosphate, and silicate minerals have been found. Among the sixteen cave mineral species recognized, atacamite, darapskite, blödite, leonite, anhydrite, and especially antarcticite are worth mentioning. In one of the samples an unknown Ca-Sr-bearing chloride mineral has also been discovered, but it has not been possible to carry out detailed mineralogical analyses. These often-rare minerals have formed in this region due to the very extreme hyperarid and salt-rich environment. This research reports the mineralogical results and proposes the genetical mechanisms leading to the formation of antarcticite, powdery anhydrite, and the paragenesis of the halite-darapskite-blödite. This study also shows that Atacama caves may be excellent analogues to study weathering processes and subsurface secondary minerals in hyperarid and hypersaline environments on Mars.

Da alcuni anni l'alternanza scuola lavoro è un percorso formativo obbligatorio per gli studenti del triennio delle scuole secondarie di II grado che consiste in una nuova modalità di apprendimento volta all'inserimento dello studente in campo universitario e lavorativo. Nell'ambito di questo progetto abbiamo partecipato a un'esperienza di ricerca tecno-scientifica presso l'Istituto di Biometeorologia di Sassari sotto la supervisione di Laura, con l'obiettivo di apprendere le metodiche di monitoraggio ambientale. Nello specifico abbiamo condotto uno studio sul ciclo del carbonio in ambiente carsico, affrontando il problema dell'impatto antropico nelle grotte tramite l'applicazione sia della micrometeorologia e della geochimica dell'anidride carbonica all'atmosfera sotterranea. Questo tirocinio ci ha impiegato per due mesi durante la tarda primavera 2019 e grazie ad esso abbiamo scoperto un nuovo mondo, quello sotterraneo.

The Atacama Desert (Northern Chile) is among the driest places on Earth, with annual rainfall below 25 mm per year and very rare flash flood events. Despite the scarcity of rainfall in this area, there are several solution caves developed in the Oligocene-Miocene evaporites of the Cordillera de la Sal, an over 100 km long, NE-SW elongated belt located at an elevation around 2,446 m asl in the Pre-Andean depression, at about 150 km East from the Pacific coast of South America. Over 50 caves and more than 15 km of salt cave passages have been explored in the last 20 years in the Cordillera de la Sal, close to San Pedro de Atacama village. These karst systems are characterized by the presence of a great variety of secondary deposits that include stalactites, flowstones, precipitates that form crusts in the streambeds and at the groundwater seeps, coatings along the cave walls, earthy masses from the cave floors and efflorescence salts on ceiling rock outcrops. Salt precipitation in this environment is controlled by the temperature dependence solubility of the species in saline water, that control the different secondary cave deposits formation. In fact, most secondary deposits found in the salt caves of Atacama are derived from the evaporation of brines (i.e. halite, gypsum, blödite, leonite), or from dehydration of gypsum induced by the hot, arid climate of the area (bassanite, anhydrite). In the framework of the project "Reading" the salt caves of Atacama", funded by the National Geographic Research and Exploration Grant, this study aims to explore the microclimatic conditions that drive cave minerals deposition within Atacama caves. For this purpose, in November 2015 and March 2018 during two multidisciplinary scientific expeditions a cave micrometeorological monitoring was performed in three different caves equipped with temperature and relative humidity data loggers that continuously recorded air masses pattern in two different seasons (summer and winter). The results have shown that Atacama cave microclimate conditions are characterized by air temperatures ranging between 15-18 °C, depending on altitude, depth below the surface, and size/number of their openings of the karst systems. Unlike most of the caves in the world, where the underground atmosphere is characterized by saturation in water vapour, cave relative humidity in this area is always very low (between 5-15%) enforced by the constant airflow through the entire cave length. This micrometeorological features control the secondary minerals precipitation on cave conduits. In fact, during the long periods of extreme dryness, evaporation of the fluids that reach the underground passages is favoured. This fluids derive from rare flash flood events during which rainwater seepages through the fractures within the host rock. The salts dissolution allows the formation of brines. The evaporation of these resulting salt-rich fluids at the cave atmosphere interface causes secondary deposits to precipitate, mostly halides and sulphates.

The Su Gologone karst spring has been recently investigated to assess how the karst aquifer would react in possible different meteorological conditions. The aim of the project is to develop a flexible and appropriate approach for its karst groundwater exploitation both taking into account the special features of the Supramonte karst landscape and without affecting the quality and quantity of the resource. For this purpose, the spring water level was continuously measured while flow rates measurements were performed monthly. From 1-year monitored, a high discharge variance and an impulsive behaviour to recharge input was detected indicating the presence of a transmissive drainage network with high hydraulic conductivity. The storage capacity associated to the low-conductive fracture system is still unknown. On the basis of these results, a new setup of the pumping facility together with a flexible management of water withdrawal is proposed, allowing the adaptation of the quantity of exploited groundwater depending on the hydro-meteorological conditions.

SHOWCAVES, un progetto di ricerca multidisciplinare che sulla base di indicatori abiotici e biotici si propone di indagare gli impatti ambientali del turismo sulle grotte turistiche e di trovare soluzioni per una loro mitigazione. Tale progetto, recentemente finaziato nell'ambito del programma PRIN 2017, e in attesa di realizzazione, viene presentato al pubblico dell'Incontro Internazionale di Speleologia, illustrando le tematiche di ricerca affrontate e le metodologie applicate per il raggiungimento degli obiettivi.

Gli ambienti carsici in rocce ad elevata solubilità cambiano continuamente in funzione di fattori naturali e antropici con scala temporale a breve e lungo termine. Fattori come gli eventi alluvionali possono indurre mutamenti rapidi e produrre importanti modificazioni nell'assetto dei reticoli sotterranei che si sviluppano in rocce evaporitiche, come quelle alitiche. A causa del riscaldamento globale, l'impatto dei cambiamenti climatici su questi sistemi carsici deve essere quindi valutato anche in condizioni di minime variazioni di piovosità. Esistono numerose tecniche per valutare queste modificazioni, che per lo più includono misure dirette sul campo con rilievi geomorfologici, di fotogrammetria (DTM) e di Laser Scanner Terrestre (TLS). L'accoppiamento delle tecniche fotogrammetriche e del TLS è la metodologia con più alta risoluzione attualmente disponibile. I vantaggi e le problematiche di queste tecniche sono state analizzate nell'applicazione per la realizzazione di rilievi ad alta definizione nelle grotte di sale della Cordigliera de la Sal nel Deserto di Atacama (Cile).

Karst processes involve the dissolution and precipitation of carbonate minerals by CO2-bearing solutions and therefore they has been included as a CO2 storage in the global carbon budget.

Cave archaeology is a scientific discipline that lies on the border between speleology and archaeology. It interprets the archaeological evidence found inside the caves. The common interest of the two scientific sectors are the analysis of the deposition processes in the cave, the features of these sediments, the reading of the stratigraphic sequences, the geochronology and the paleoclimate and paleo-environmental reconstructions. The speleology offers to the archaeologist important tools to reconstruct the context in which the human presence occurred. Thanks to its skills in karst sciences, speleology allows the reconstruction of the environment in which a given archaic community was settled, its interactions with the past environment, the motivations that led to choosing a particular site and eventually to abandon it. Moreover, highlights the erosion that time has exercised on reminds, cave science also permits to evaluate the quality of information that has reached to our days. At the same time, archaeological evidences provide invaluable records for the study of geomorphological, sedimentological and soil processes in karst environments. In fact, as datable elements, archaeological reminds can be useful chronological indicators for paleo-environmental and paleoclimate reconstructions. The aim of this study is to focus on how the connections between archaeology and speleology consent to better understand the relationship between man and environments in the past, illustrating the results of some multidisciplinary excavations carried out in caves around the town of Sassari (Sardinia, Italy) which provided new information on prehistoric cultures dating back as far as about 6,000 years ago, the oldest in the area. This research has highlighted that the interaction between these two specialists overcomes some cognitive obstacles, such as the difficulties of operating in the underground environment and interpreting the paleo-environmental context for archaeologists, and the importance to preserve during explorations cultural records found within caves for the speleologists.

Summary In situ measurements of discharge, pH, electric conductivity (EC), temperature, and SiO2 content have been carried out during five expeditions in the last 20 years on the summit plateaus, inside caves and along the rivers of the surrounding lowlands of three tepui massifs in Venezuela (Auyan, Roraima, and Chimanta). Additionally, detailed chemical analyses were performed on waters sampled in a newly discovered extensive quartz-sandstone cave system on the Auyan Tepui. Rock samples of the quartz-sandstone bedrock from different locations have been analysed to obtain their chemical composition with a wavelength dispersive X-ray fluorescence spectrometer. These data show that the majority of silica present in surface and subsurface water comes from dissolution of quartz and only in minor amount from hydrolysis of other silicate minerals. Probably the presence of a hardened crust of iron hydroxides limits the dissolution of silica on the top surface of tepuis. Dissolution in the subsurface, instead, is more significant and causes, in the long term, the “arenisation” of the quartz-sandstone and its subsequent removal by mechanical erosion. On the other hand, waters flowing on the arkosic rock outcropping on the lowland below the tepuis obtain their high dissolved silica content mainly from hydrolysis of silicates. The morphological evolution of these table mountains appears thus to be controlled mainly by the underground weathering of the quartz-sandstone, with the opening of deep fractures (grietas) and the collapse of large underground horizontal cave systems. Scarp retreat, instead, seems to be related to the higher weathering rate of the more arkosic formations underlying the quartz-sandstones.

The report analyzes the state of the art of the literature on the environmental impact of the sheep supply chain, relatively to global warming. LCA studies on sheep productions (meat, wool, milk and cheese, ecosystem services) and on post-farm emissions were reviewed and discussed focusing their methodological approach and main outcomes. Studies focusing the most important biological and technical option for the reduction of methane emissions, nitrogen excreta and variation of soil carbon stock were also reviewed and discussed. The report allowed to deduce important information for the planning of emission mitigation strategies to be applied in dairy sheep sector at territorial level in the European sheep farming systems.

This document concerns the preliminary analysis of the primary data collected for the LCA studies of the Sardinian sheep farms involved in the SheepToShip LIFE project. This is a technical report that start to identify, quantify, control and critically evaluate all information extract from the Life Cycle Inventory. It should be considered as preliminary because LCA data are still thorough the final revision.

The recent exploration of a new sinkhole found along the Flumineddu fluviokarst canyon (Sardinia, Italy) has presented the opportunity to investigate a further segment of the Supramonte karst aquifer. In this work, the result of a dye-tracing test performed in the Piggios de Janas Cave is presented together with an updated view on the current understanding of the hydrogeology of this area. A water connection between this new discovery and Su Colostrargiu Cave has been detected, unveiling another part of the S'Edera-Su Gologone karst system. Furthermore, three distinct groundwater drainages have been recognized at 250, 450 and 650 m asl, within S'Eni 'e Istettai Cave, S'Orale 'e Su Mudrecu Cave and Su Colostrargiu Cave, respectively. Within each of these caves a river flows in vadose conduits developed along the main fractures, parallel to each other, but at different altitudes determined by the fault-dislocated basement position.

The reliability of a post-IR elevated temperature IRSL (290 °C; pIRIR290) is tested on wind-blown, sand-sized (180–250 μm) K-rich feldspar grains. The pIRIR290 ages were compared with quartz SAR-OSL data, other independent age controls and historical information. Three study areas along the coast of Sardinia (Italy) were selected: the south Alghero coast, the Bue Marino cave (E Sardinia) and the Alghero bay (NW Sardinia). Along the south Alghero coastline a thick dunefield system is widely recognised in the literature to represent the beginning of the last glacial phase (post 80 ka). From a single block sand-sized grains for quartz SAR-OSL and K-feldspar pIRIR dating were collected. The natural quartz SAR-OSL sample lies below the saturation limit of the dose response curve (De

International audience; Chemical and physical proxy data from a precisely dated early last glacial (similar to 113-110 ka, MIS5d) Sardinian stalagmite reveal a sub-millennial-scale, cool-dry climate event centered at 112.0 (+0.52)/(-0.59) ka, followed by a rapid return to warm-wet conditions at 111.76 (+0-43)/(-0.45) ka. Comparison with regional speleothem records and the palaeotemperature proxy record from the NGRIP ice core (Greenland) suggests that this event corresponds to Greenland Interstadial (GI) 25b and 25a, an intra-interstadial climate oscillation within GI-25, according to the recent Greenland stratigraphic framework. The speleothem age is in reasonable agreement (within 0.8 kyr) with that of the corresponding event in Greenland based on the GICC05modelext ice chronology but is older by about 3.7 kyr than the Greenland age based on the AICC2012 chronology. (C) 2017 Elsevier Ltd. All rights reserved.

In July 2016 the SheepToShip LIFE project was financed by the EU LIFE Programme Climate Action 2014-2020 with the aim to reduce the greenhouse gas emissions from the dairy sheep sector in Sardinia, an absolute leader on dairy sheep raising [4]. In particular, the main objective of the project is to reduce by 20% in 10 years GHG emissions (nitrous oxide, methane and carbon dioxide) from the Sardinian dairy sheep supply chain. The immediate goals of the project are to encourage the environmental improvements of production systems in the sheep sector and to demonstrate the environmental, economic and social benefits deriving from eco-innovation in the dairy industry and sheep farming sector. Additionally, its actions promote the implementation of environmental policies and rural development, guided by the Life Cycle Thinking approach, and aimed at enhancing the environmental quality of local sheep's milk and cheese supply chains. Furthermore, one of the project scopes is to increase the level of knowledge and awareness of stakeholders and the general public regarding the environmental sustainability of products made from sheep's milk and their contribution to the mitigation of climate change. With this approach, the project expects to achieve the development of a common methodology for analysing the life-cycle of sheep's milk supply chains. This procedure will be used to determine the environmental impact of the sheep's milk business in Sardinia, including the environmental hotspots of the life-cycle of Sardinian Protected Designation of Origin (PDO) sheep's cheese, and will be tested in several cases study (sheep farms and sheep dairy businesses) through the introduction of low-input techniques compatible with maintaining quality standards of products.

The report analyzes the state of the art of the literature on the environmental impact of the sheep supply chain, relatively to global warming. LCA studies on sheep productions (meat, wool, milk and cheese, ecosystem services) and on post-farm emissions were reviewed and discussed focusing their methodological approach and main outcomes. Studies focusing the most important biological and technical option for the reduction of methane emissions, nitrogen excreta and variation of soil carbon stock were also reviewed and discussed. The report allowed to deduce important information for the planning of emission mitigation strategies to be applied in dairy sheep sector at territorial level in the European sheep farming systems.

This document contains practical guidelines and methodological standards concerning on-field data collection for LCA studies carried out within the SheepToShip LIFE project. It is targeted to technicians devoted to field LCA data collection.

The Su Bentu Cave has been recently investigated to determine the geochemical features of its groundwater. The analyses have shown a low mineralization with calcium bicarbonate character. Its main composition is explained by calcite dissolution and mainly reflects both cave lithology and rainwater input. A slight increase in sodium and sulphate contents is the only exception to this pattern that may be related to the weathering of the sediments filling the cave conduits. These preliminary results have been compared with the available data on Su Gologone spring, the main karst outlet of the Supramonte aquifer (Sardinia, Italy) to whose the cave is tributary. The same alkaline–earth bicarbonate character is also observed in the spring water, but the salinity and the concentration of main ions generally increase due to longer residence time. Moreover, for the discharge point, major magnesium content indicates a dominant circulation in Jurassic dolomites outcropping nearby.

The karst of Sorbas (SE Spain) is one of the most important gypsum areas worldwide. Its underground karst network comprises over 100 km of cave passages. Rounded smooth forms, condensation cupola and pendant-like features appear on the ceiling of the shallower passages as a result of gypsum dissolution by condensation water. Meanwhile, gypsum speleothems formed by capillarity, evaporation and aerosol deposition such as coralloids, gypsum crusts and rims are frequently observed closer to the passage floors. The role of condensation–dissolution mechanisms in the evolution of geomorphological features observed in the upper cave levels has been studied by means of long-term micro-erosion meter (MEM) measurements, direct collection and analysis of condensation waters, and micrometeorological monitoring. Monitoring of erosion at different heights on gypsum walls of the Cueva del Agua reveals that the gypsum surface retreated up to 0.033 mm yr− 1 in MEM stations located in the higher parts of the cave walls. The surface retreat was negligible at the lowest sites, suggesting higher dissolution rates close to the cave ceiling, where warmer and moister air flows. Monitoring of microclimatic parameters and direct measurements of condensation water were performed in the Covadura Cave system in order to estimate seasonal patterns of condensation. Direct measurements of condensation water dripping from a metal plate placed in the central part of the El Bosque Gallery of Covadura Cave indicate that condensation takes place mainly between July and November in coincidence with rainless periods. The estimated gypsum surface lowering due to this condensation water is 0.0026 mm yr− 1. Microclimatic monitoring in the same area shows differences in air temperature and humidity of the lower parts of the galleries (colder and drier) with respect to the cave ceiling (warmer and wetter). This thermal sedimentation controls the intensity of the condensation–evaporation mechanisms at different heights in the cave.

This work reports the results of geomorphological observations carried out in the coastal Fico Cave and surrounding areas (Baunei, Central East Sardinia) in the Gulf of Orosei. A tidal notch, generally believed to be of Eemian (MIS 5e) age, is barely visible at 8.5 above present sea level (asl), some metres below the main entrance of the cave. Old cave passages, now partially opened by cliff retreat and parallel to the coastline, are clearly visible at around 14 m asl and correspond to the main level of Fico Cave. Two more notches are located higher, at 22 and 50 m asl. Fico Cave itself is composed of at least 6 clearly distinguished more or less horizontal levels (− 10 m below present sea level (bsl), and + 14, + 22, + 40, + 50, and + 63 m asl), independent of the stratal dip, arguing for a sea-level, and hence, fresh-water lens control. Cave passages develop along main fractures more or less parallel to the coastline and never extend landward for more than 150 m, mostly ending blindly, or diminishing in their dimensions progressively landward. Most passages only contain clay deposits, lacking fluvial or marine sediments or typical fluvial erosion morphologies (i.e. scallops). It is suggested from this body of evidence that Fico Cave was formed in the coastal mixing zone along major discontinuities during several Quaternary interglacial periods, when sea level was high and relatively stable for enough time to develop large dissolutional voids. The geomorphological observations indicate the main + 14 m asl level of the cave to have formed during MIS 9, and was heavily reworked during MIS 5, while the higher levels are relative to older interglacial highstands that occurred between 1 Ma and 325 ka. The small active branch developed below present sea level has formed during MIS 7 (225 ka). These observations shed new light on the position of the MIS 5e highstand markers in this area of the coast, much higher than previously thought.

The “espada” speleothems of Cueva de las Espadas (Naica Mine, Chihuahua, Mexico) comprise a high-purity selenite core overlain by successive deposits of calcite, gypsum and aragonite. Gypsum precipitated under water from a hydrothermal solution (~ 58°C) when the water table was above the cave level ca. 57 ka, during the last glaciation, and some intervals during deglaciation and the Holocene. Aragonite was deposited at lower temperatures (~ 26°C) in a perched lake occupying the cave bottom, when the water table dropped below the cave level during brief dry intervals during deglaciation and the early Holocene. The isotopic composition of gypsum water of crystallization shows that the deglaciation–Holocene aquifer water was enriched in deuterium by 12.8–8.7‰ relative to water from the last glaciation. This is attributed to an increased relative moisture contribution from the Gulf of Mexico during deglaciation and the Holocene compared to the last glaciation. This indicates that drier conditions occurred in the Naica area during the Holocene than around 57 ka. Furthermore, trace element analyses of gypsum served to deduce the circulation regime of the Naica aquifer during the past 60,000 yr, and also suggest that higher aquifer recharge occurred during the last glaciation.

The present work deals with the results of long-term micro-erosion measurements in the most important gypsum cave of Spain, the Cueva del Agua (Sorbas, Almeria, SE Spain). Nineteen MEM stations were positioned in 1992 in a wide range of morphological and environmental settings (gypsum floors and walls, carbonate speleothems, dry conduits and vadose passages) inside and outside the cave, on gypsum and carbonate bedrocks and exposed to variable degree of humidity, different air flow and hydrodynamic conditions. Four different sets of stations have been investigated: (1) the main cave entrance (Las Vinicas spring); (2) the main river passage; (3) the abandoned Laboratory tunnel; and (4) the external gypsum surface. Data over a period of about 18 years are available. The average lowering rates vary from 0.014 to 0.016 mm yr− 1 near the main entrance and in the Laboratory tunnel, to 0.022 mm − 1 on gypsum floors and 0.028 mm yr− 1 on carbonate flowstones. The denudation data from the external gypsum stations are quite regular with a rate of 0.170 mm yr− 1. The observations allowed the collecting of important information concerning the feeding of the karst aquifer not only by infiltrating rainwater, but under present climate conditions also by water condensation of moist air flow. This contribution to the overall karst processes in the Cueva del Agua basin represents over 20% of the total chemical dissolution of the karst area and more than 50% of the speleogenetically removed gypsum in the cave system, thus representing all but a secondary role in speleogenesis. Condensation–corrosion is most active along the medium walls, being slower at the roof and almost absent close to the floor. This creates typical corrosion morphologies such as cupola, while gypsum flowers develop where evaporation dominates. This approach also shows quantitatively the morphological implications of condensation–corrosion processes in gypsum karst systems in arid zones, responsible for an average surface lowering of 0.047 mm yr− 1, while mechanical erosion produces a lowering of 0.123 mm yr− 1.

Terrestrial ecosystems play a fundamental role in the context of the global carbon budget acting as net sinks of CO2 through their photosynthesis processes. Urban environments are CO2 source hot spots resulting from the sum of biogenic and human contributions, with fossil fuel combustion being the main responsible of anthropogenic emissions. Moreover, cities center typically records higher temperatures than rural surroundings (urban heat island effect) due to a presence of buildings and complex surfaces with respect to trees and lawns. In this work, eddy covariance measurements of carbon dioxide exchange from two different nearby sites (a natural Mediterranean maquis ecosystem and an urban site in central Sassari, Italy) have been analysed and compared over the same multi-seasonal period aiming to characterize the daily and seasonal trend of carbon fluxes. Due to their proximity, the two sites are expected to experience similar weather conditions but differences in air temperature, humidity, and precipitation have been further investigated. CO2 exchanges are significantly different between the two sites: in the natural site, carbon fluxes show a seasonal and diurnal pattern linked to the physiological activity of the vegetation and soil microrganism (with peaks of fluxes occurring in spring and autumn) whereas during the summer months carbon uptake decrease due to water stress conditions. At the urban site, carbon fluxes are characterized by a different trend, especially at daily scale, where peaks emissions are clearly related to traffic. Similarities are observed during the summer weekends, due to urban vegetation uptake and a decrease in vehicular traffic (holiday period). Other emissions sources in the urban site have been analyzed, such as domestic heating during winter months, as well as the mitigation potential of increased vegetated areas.

Capo Caccia karst area (North-West Sardinia, Italy) is one of the monitoring points of the Italian ICOS infrastructure. The carbon flux in this region is continuously performed by direct measurement of gas exchanges across canopy-atmosphere interface using an eddy covariance tower placed over a Mediterranean maquis, constituted by sclerophyl species. As the net ecosystem carbon balance in this terrestrial ecosystem does not only respond to physiological features of its vegetation, the geological contribution to the GHG budget has been investigated through the relationships among atmosphere-biosphere-geosphere gas exchanges. Since carbon dioxide is involved in the geochemical cycle of the karst processes, the environmental monitoring programme has been extended to the underground atmosphere using micrometeorological stations installed within caves. The preliminary data show a static cave air CO2 concentration ranging from 500 ppm to 1600 ppm, with periodic gas plumes that reach up to 18,000 ppm. Correlation analysis point out that subsurface-atmosphere gas exchange reflects environmental forcing related to atmospheric variables. In fact the degassing mainly occurs by barometric pressure changes and via density driven flow. Subsurface air ventilation can be also induced by water table oscillations, so future step of the study will take into account the relationship between the unsatured zone and the near marine ecosystem. Even though underground air mass is reasonably small respect to the outside atmosphere, when considering the high density of karst features of Capo Caccia karst ecosystem, its temporal CO2 pattern provides evidence that the amounts of carbon that might be released from subsurface could be noticeable at both local and regional scale. Integrated monitoring of atmosphere dynamic can give clues for understanding carbon cycle model and multidisciplinary approaches contribute for filling the gap in global carbon budget.

The IPCC Fifth Assessment Report (AR5) accounts an increase of the total annual anthropogenic GHG emissions between 2000 and 2010 that directly came from the transport sector. In 2010, 14% of GHG emissions were released by transport and fossil-fuel-related CO2 emissions reached about 32 GtCO2 per year. The report also considers adaptation and mitigation as complementary strategies for reducing the risks of climate change for sustainable development of urban areas. This paper describes the on-road traffic emission estimated in the framework of a Sardinian regional project [1] for the town of Sassari (Sardinia, Italy), one of the Sardinian areas where the fuel consumption for on-road transportation purposes is higher [2]. The GHG emissions have been accounted (a) by a calculation-based methodology founded on a linear relationship between source activity and emission, and (b) by the COPERT IV methodology through the EMITRA (EMIssions from road TRAnsport) software tool [3]. Inventory data for annual fossil fuel consumption associated with on-road transportation (diesel, gasoline, gas) have been collected through the Dogane service, the ATP and ARST public transport services and vehicle fleet data are available from the Public Vehicle Database (PRA), using 2010 as baseline year. During this period, the estimated CO2 emissions accounts for more than 180,000 tCO2. The calculation of emissions due to on-road transport quantitatively estimates CO2 and other GHG emissions and represents a useful baseline to identify possible adaptation and mitigation strategies to face the climate change risks at municipal level.

Ojo de la Reina is the first and the smallest cave intersected at the -290 level in the Naica Mine (Mexico), therefore it was the first cavity in which the lowering of temperature induced by mine ventilation caused condensation over crystals’ surface since 2005. The consequent dissolution of the gypsum crystals and subsequent condensed water evaporation lead to the deposition of several new minerals, among which some highly soluble Mg/Na compounds (bloedite, epsomite, halite, hexahydrite, kieserite, starkeyite). The single available source of Mg and Na ions in this minerogenetic environment is represented by the huge fluid inclusions widespread within the crystals. The condensation occurs mainly along the widened principal exfoliation (010) planes, and allows to an easy and fast opening of the fluid inclusions that consequently drip Mg-rich fluids stored inside them. Finally the evaporation of the relatively small volumes of involved water allows to the development of the high soluble Mg and Na compounds.

The caves of Naica (Chihuahua, Mexico) are perhaps the most famous mine caves of the world due to the presence of gigantic gypsum crystals. Nevertheless, very little research has been carried out on these crystals until now. An international multidisciplinary investigation started in 2006 with the aim not only to define the genesis and the age of the Naica gypsum crystals, but also to focus other important scientific aspects of these caves and to ensure a complete documentation and knowledge of these natural wonders which will not be accessible anymore in a few couple of years. The preliminary results of this, still in progress, research allow to date the giant crystals and to define the boundary conditions and the mechanisms which induced their development. For the first time pollens have been extracted from gypsum crystals and their analyses evidenced that some 35 Ky BP the Naica climate was cooler and more humid than today.

Unusual orange ochre crusts were recently discovered in Crovassa Ricchi in Argento Cave (San Giovanni Mine, SW Sardinia). These speleothems appear covering the cave walls on hydrothermal calcite spars as well as filling widened spaces between calcite crystals. Planar crusts display geometrical forms following the boundaries between the calcite spars. EDX-SEM microanalyses reveal that these deposits comprise substances of Fe, Mn, Pb, Zn and O that occur as solid inclusions in pits on the surface of altered calcite microcrystals. Micro-Raman spectroscopy analyses suggest the presence of calcite and ferromanganese oxides with a low degree of crystallinity. The genetic mechanism proposed for these speleothems describes an initial stage of precipitation of euhedral calcite crystals from warm water under subaqueous conditions. The crystal surfaces were eroded and corroded by colder aggressive water that smoothed the surfaces of the crystals and slightly widened the spaces between calcite spars. Metal-rich mud coming from alteration of bedrock and ore bodies filled the cave, also penetrating along the spaces between the calcite spars. When the water table fell below the cave level, part of the sediments was eroded but the cave walls remained covered with metal-rich clayey sediments. Under aerobic conditions, metals - which were reduced in previous stages - oxidized to oxides, lowering the pH and thus the crystal surface and the calcite planes between the spars were corroded. Subsequently, the polymetallic crusts became harder through evaporation within the cave, "fossilizing" the products of this process within the planes between spars. Finally, the exposed calcite surfaces continued to be altered due to CO2 diffusion into condensation water, while the boundaries between crystals were preserved against corrosion thanks to the crust coating. As a result, the external crystal edges protrude by several centimeters from the current cave wall, while the crystal surfaces are depressed, giving rise to calcite "ghosts". © 2013 Elsevier B.V. All rights reserved.

Relazione scientifica redata 2015 a conclusione del progetto CO2.0 - Sviluppo, verifica funzionale e messa a punto di un sistema integrato per la quantificazione degli scambi netti di CO2 e per la valutazione di strategie di mitigazione a livello urbano e territoriale. Legge Regionale 7 agosto 2007, n. 7 Promozione della ricerca scientifica e dell'innovazione tecnologica in Sardegna

The Mesozoic carbonate platform of NW Sardinia (Italy) pertains to the historical region of Nurra and since 1999 to the Regional Natural Park of Porto Conte. The area is also part of the Fluxnet project, a global network that coordinates the analysis of the net ecosystem carbon balance by direct measurement of gas exchanges across canopy-atmosphere interface using micrometeorological flux tower. The carbonate terrains of this sector host well-developed cave systems. The karst aquifer has a high dissolved carbon and the underground atmosphere is often characterised by anomalous level of carbon dioxide that has never been investigated before. As geological diffusive background emission over the carbonate outcrop was previously neglected, this study is aimed to assess the magnitude of the CO2 outgassing from caves to outside atmosphere. An environmental monitoring programme has been carried out in the Monte Doglia cave, a 100 m-deep vertical shaft located at 320 m asl and 2 km far from the coast. It opens in an area where a significant part of the surface is bare rock. The soil cover, where it exists, rarely exceeds 20 cm in thickness and consists of fine red, sandy material. The natural vegetation consists mainly of shrubs. The cave is monitored with multiple meteorological sensors that record continuously air CO2 and microclimatic parameters. Carbon dioxide concentration is measured at -10 m depth from the entrance by an infrared spectrometer (NDIR technology, range 0-10,000 ppm). Preliminary data indicate periodic oscillations of cave air CO2 levels ranging from 500 ppm to 1600 ppm, punctuated by events that provide clues to ventilation and degassing mechanisms. These gas plumes reach concentration >10,000 ppm. This huge CO2 content is hidden when a prevailing advective-renewal of cave air is established. Ventilation occurs via density driven flow and by wind across the entrance. Subsurface airflow in unsatured zones can be also induced by atmospheric pressure fluctuations, topographic effects, water table oscillations and meteoric water infiltration. About the origin of this CO2-rich gas, examples of volatiles escapes along faults have been documented in Sardinia. They have been related to mantle-derived fluxes associated to Quaternary volcanism. Other non-volcanic degassing involved on natural CO2 emissions from Nurra karst terrain might derive from carbonate rock weathering, oxidation of sulphur deposits and surface processes. Future stable isotopes analyses will be devoted to clarify these points. Finally, by considering the density of cave entrances and the contribution of numerous fractures widespread in the karst terrain, the temporal CO2 pattern of Nurra region provides evidence that the amounts of carbon that might be released from subsurface atmosphere in the vadose zone could be noticeable at both local and regional scale.

Although suppression of apoptosis has been implicated as a mechanism for the hepatocarcinogenicity of peroxisome proliferators (PPs), they can also induce cell death in rat AH130 and human HepG2 hepatoma cells. To study how PPs induce cell death and to characterize the molecular events involved, we administered the hypolipidemic BR931, a peroxisome proliferator, to rat hepatoma FaO cells. Treatment with increasing concentrations of BR931 (0.015 to 0.6 mM) reduced cell viability in a dose- and time-dependent manner, associated with DNA fragmentation and morphological changes characteristic of apoptosis. BR931 also caused phosphorylation of p53 within 3 hours, translocation of the pro-apoptotic Bax protein to mitochondria, release of cytochrome-c into the cytosol, and activation of caspase-9 and -3. These results indicated that BR931 activated the intrinsic caspase cascade. Pretreatment with three different antioxidants, N-acetylcysteine, Vitamin C and Trolox, reduced apoptosis, suggesting that reactive oxygen species (ROS) plays a role in BR931-induced apoptosis. In support of this hypothesis, BR931 produced increased levels of 8-hydroxy-deoxy-guanosine, a marker of DNA oxidative damage. Antioxidants prevented the p53 phosphorylation, up-regulation of Bax and BR931-induced apoptosis. These results suggest that BR931 can increase generation of ROS, leading to DNA damage and p53 phosphorylation, which, in turn, induces the activation of Bax, release of cytochrome-c from mitochondria and activation of caspases, culminating in cell death.

The paper presents a detailed study demonstrating the hypogenic origin of the Corona 'e Sa Craba quartzite cave in SW Sardinia (Italy). Although the quartzite host-rock of this cave derived from silicification of Cambrian dolostones and dissolution of carbonate remnants could have had a role in the speleogenesis, detailed morphologic and petrographic investigation revealed clear evidence of quartz dissolution without signs of mechanical erosion by running waters. Thin section microscopy and scanning electron microscope (SEM) images show pervasive dissolution morphologies, such as pits and notches on quartz crystals causing the deep arenization of the cave walls, suggesting that the dissolution of quartz had a primary role in the formation of the void. The study of secondary cave minerals and the sulfur isotopic composition of sulfates and sulfides, coupled with data on fluid inclusions, allowed reconstruction of the peculiar speleogenetic history of this hypogenic hydrothermal quartzite cave. The cave formed by reduced hydrothermal fluids, probably under basic neutral pH in phreatic conditions. The presence of abundant cations of Ba2+ in reduced Cl-rich fluids enhanced the quartz dissolution rate, allowing the formation of the voids in deep settings. During the Late Oligocene uplift of the area, the hydrothermal fluids in the cave reached oxygen-rich conditions, thus a minerogenetic phase started with the deposition of barite when the temperature of the fluid was

Although hypogene cave systems have been described since the beginning of the 20th century, the importance in speleogenesis of ascending fluids that acquired their aggressiveness from in-depth sources has been fully realized only in the last decades. Aggressiveness of waters can be related to carbonic and sulfuric acids and the related corrosion-dissolution processes give rise to different types of caves and underground morphologies. The abundance of hydrothermal springs and associated travertine deposits, and the widespread interaction between volcanic or sub-volcanic phenomena and karst in many sectors of the Italian peninsula are a strong evidence of hypogene speleogenesis. Furthermore, researches on secondary minerals have allowed to discover hypogene caves formed by highly acidic vapors in subaerial environments, also showing that most of these caves have extremely rich mineral associations. Despite this, until the late 1980s the only known important cave systems of clear hypogene origin in Italy were considered to be the ones hosted in the Frasassi Canyon and Monte Cucco, in which important gypsum deposits undoubtedly showed that sulfuric acid played an important role in the creation of voids (Galdenzi, 1990, 2001; Galdenzi & Maruoka, 2003; Menichetti et al., 2007). Afterwards many other caves were categorized as formed by the sulfuric acid speleogenesis throughout the entire Apennines. Following the broad definition of hypogene caves by Palmer in 1991, and the even more general one of Klimchouk in the last decade (Klimchouk, 2007, 2009), the number of caves considered of hypogene origin in Italy has grown rapidly. Figure 1 shows the hypogene karst systems of Italy, including, besides the well-known and published ones, also the known and less studied, and presumed hypogene cave systems (see also Table 1). More recently, in some of these caves detailed studies have been carried out including geomorphology, mineralogy, and geochemistry. Sulfuric acid caves are known from many regions along the Apennine chain (Tuscany, Umbria, Marche, Latium, Campania, Calabria) (Forti, 1985; Forti et al., 1989; Galdenzi and Menichetti, 1989, 1995; Galdenzi, 1997, 2001, 2009; Galdenzi et al., 2010; Piccini, 2000; Menichetti, 2009, 2011; Mecchia, 2012; De Waele et al., 2013b), but also from Piedmont, Apulia, Sicily (Vattano et al., 2013) and Sardinia (De Waele et al., 2013a). In this last region ascending fluids have also formed a hypogene cave in quartzite rock. Oxidation of sulfides can locally create hypogene cave morphologies in dominantly epigenic caves, such as in the Venetian forealps (this cave is not shown in Figure 1, being largely epigenic in origin) (Tisato et al., 2012). Ascending fluids have also created large solution voids in Messinian gypsum beds in Piedmont, and these can be defined hypogene caves according to the definition by Klimchouk (Vigna et al., 2010). Some examples of hypogene cave systems due to the rise of CO2-rich fluids are also known in Liguria and Tuscany (Piccini, 2000). In the Alps and Prealps (Lombardy), some ancient high mountain karst areas exhibit evidences of an early hypogene origin, deeply modified and re-modeled by later epigenic processes. Hypogene morphologies are thus preserved as inactive features, and it is often difficult to distinguish them from epigenic ones. At almost twenty years distance from the first review paper on hypogene cave systems in Central Italy by S. Galdenzi and M. Menichetti (1995), we give a review of the state-of-the-art knowledge on hypogene caves actually known from the whole of Italy.