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The Trichocentrum cepula complex comprises three species, T. caatingaense, T. cepula and T. sprucei, endemic to tropical forests east of the Andes in South America. The delimitation of these species has been diversely interpreted due to the extensive morphological variation in the complex. We applied an integrative approach to achieve a better understanding of these biological units, using geometric morphometrics, cytogenetic analysis (chromosome counts and CMA/DAPI banding) and molecular phylogenetics (ITS and rpl32-trnL). An initial morphometric analysis using the pre-identified specimens into three taxa suggested that T. sprucei is distinct from the other two, which show some overlap. A subsequent analysis of the labellum, including only T. caatingaense and T. cepula organized in six pseudo-populations, suggested the existence of four morphological groups. All analysed specimens presented 2n = 36 chromosomes, CMA+/DAPI− terminal bands and CMA−/DAPI+ pericentromeric bands, which varied in number across species, localities or even individuals from the same locality. The notable variation in DAPI+ pericentromeric bands may be related to transposable elements that could also be a factor influencing the wide morphological variation in the flowers. In the phylogenetic analysis, the specimens belonging to T. caatingaense formed a strongly supported clade sister to the rest, whereas the specimens belonging to T. cepula and T. sprucei emerged together, with their relationships tending to be determined by geographic proximity. The evidence we generated suggests that treating the Brazilian populations of this species complex under a single name, T. cepula, provides more taxonomic stability and utility, thus the necessary taxonomic changes are implemented. [ABSTRACT FROM AUTHOR]

Galdieria sulphuraria is a unicellular red alga that lives in hot, acidic, toxic metal-rich, volcanic environments, where few other organisms survive. Its genome harbors up to 5% of genes that were most likely acquired through horizontal gene transfer. These genes probably contributed to G.sulphuraria 's adaptation to its extreme habitats, resulting in today's polyextremophilic traits. Here, we applied RNA-sequencing to obtain insights into the acclimation of a thermophilic organism towards temperatures below its growth optimum and to study how horizontally acquired genes contribute to cold acclimation. A decrease in growth temperature from 42°C/46°C to 28°C resulted in an upregulation of ribosome biosynthesis, while excreted proteins, probably components of the cell wall, were downregulated. Photosynthesis was suppressed at cold temperatures, and transcript abundances indicated that C-metabolism switched from gluconeogenesis to glycogen degradation. Folate cycle and S-adenosylmethionine cycle (one-carbon metabolism) were transcriptionally upregulated, probably to drive the biosynthesis of betaine. All these cold-induced changes in gene expression were reversible upon return to optimal growth temperature. Numerous genes acquired by horizontal gene transfer displayed temperature-dependent expression changes, indicating that these genes contributed to adaptive evolution in G.sulphuraria. [ABSTRACT FROM AUTHOR]

Abstract In the period July 2005–October 2006 several soil gas prospections were performed on the island of Pantelleria, an active volcanic/geothermal system at present in a quiescent state. Measured parameters were CO 2 concentrations and 220Rn and 222Rn activities at 50 cm depth and CO 2 fluxes from the soil. The whole island was covered with a measurement density of 3.5 points/km2 for CO 2 (flux and concentration) and 1.6 points/km2 for Rn. Further three main and seven minor areas of previously ascertained or expected exhalative activity were covered with a measurement density up to 100 points/km2. The obtained results ranged from 0.038 to 95%vol for CO 2 concentration, from 10 Bq/m3 to 164,000 Bq/m3 from 10 Bq/m3 to 750,000 Bq/m3 for 220Rn and 222Rn activities, respectively and from <0.1 to 4700 g/m2 day for CO 2 fluxes. Probability plots evidenced for all measured parameters the presence of three populations (background, mixed and hydrothermal). All anomalous values were found in the central part of the island within the youngest caldera. Flux data allowed us to estimate a total CO 2 output of the volcanic/geothermal system of Pantelleria in 24.2 tons per day. Some new exhaling area, significantly contributing to the total output and characterised by stunted or absent vegetation, were evidenced on the southern flank of Mt. Grande. At one of these areas the relationships between the measured parameters and vegetation cover were studied in detail along a 140 m long transect of 15 points. Finally, a first evaluation of the gas hazard related to the geogenic degassing evidenced some high risk area at the mofette along the shores of the Lake Specchio di Venere (CO 2) and in the village of Rekale (CO 2 and Rn). [ABSTRACT FROM AUTHOR]

A comprehensive hydrogeochemical study of the cold and thermal groundwaters of the presently quiescent volcanic system at Methana was undertaken that involved collecting 71 natural water samples. Methana is a peninsula in Peloponnesus, Greece whose arid climate and hydrological situation is similar to that of the nearby small islands of the Aegean Sea. Similarly, the chemical and isotopic compositions of its water are dominated by the mixing of seawater with meteoric water both through direct intrusion and meteoric recharge. However, the simple mixing trends at Methana are modified by water–rock interaction processes, enhanced by the dissolution of endogenous CO 2 , which lead to strong enrichments in alkalinity, Ca, Ba, Fe and Mn. The thermal waters show very high salinity that is sometimes close to that of seawater [total dissolved solids (TDS) = 8.5–40 g/l]. Although the cold groundwaters sometimes also show elevated TDS values (up to 6.3 g/l), their overall quality is acceptable due to the trace metal and nitrate contents mostly being below acceptable limits. While the saltiest groundwaters are not acceptable for human consumption, they are used for irrigation without exerting toxic effects on plants, which is probably due to the high permeability of the soils not supporting salt accumulation and salinity-resistant crops being cultivated. [ABSTRACT FROM AUTHOR]

The chemical composition of the groundwater at Mt. Etna was investigated in order to determine the extent to which the persistent plume affects the chemical composition of circulating waters. Samples from 31 springs and wells were collected during June and July 2014 and analyzed for their chemical compositions. The content of dissolved elements derives from the bulk deposition (wet and dry deposition) at the recharge areas as well as from the weathering of volcanic rocks during the infiltration and transport of groundwater. In its early phase, the chemical weathering of volcanic rocks and ashes is promoted by the acid rain that characterizes the area and subsequently by the huge amount of deep magmatic carbon dioxide (CO 2 ) coming up through the volcanic edifice and dissolving in the water. The high content of chlorine is mainly derived from interactions between the plume and rainwater, while the total alkalinity can be completely ascribed to the dissociation of carbonic acid (H 2 CO 3 ) after the hydration of CO 2 . The relative contributions of plume-derived elements/weathering and CO 2 -driven weathering has been computed for each element. In addition, the comparison between the chemical compositions of the bulk deposition and of groundwater provides a new understanding about the mobility of volatile elements. The proposed approach has revealed that the persistent plume strongly affects the chemical composition of groundwater at Mt. Etna and probably also at other volcanoes characterized by huge open-conduit degassing activity. [ABSTRACT FROM AUTHOR]

Active biomonitoring using moss-bags was applied to an active volcanic environment for the first time. Bioaccumulation originating from atmospheric deposition was evaluated by exposing mixtures of washed and air-dried mosses ( Sphagnum species) at 24 sites on Mt. Etna volcano (Italy). Concentrations of major and a large suite of trace elements were analysed by inductively coupled mass and optical spectrometry (ICP-MS and ICP-OES) after total acid digestion. Of the 49 elements analysed those which closely reflect summit volcanic emissions were S, Tl, Bi, Se, Cd, As, Cu, B, Na, Fe, Al. Enrichment factors and cluster analysis allowed clear distinction between volcanogenic, geogenic and anthropogenic inputs that affect the local atmospheric deposition. This study demonstrates that active biomonitoring with moss-bags is a suitable and robust technique for implementing inexpensive monitoring in scarcely accessible and harsh volcanic environments, giving time-averaged quantitative results of the local exposure to volcanic emissions. This task is especially important in the study area because the summit area of Mt. Etna is visited by nearly one hundred thousand tourists each year who are exposed to potentially harmful volcanic emissions. [ABSTRACT FROM AUTHOR]

Volcanic emissions were studied at Mount Etna (Italy) by using moss-bags technique. Mosses were exposed around the volcano at different distances from the active vents to evaluate the impact of volcanic emissions in the atmosphere. Morphology and mineralogy of volcanic particulate intercepted by mosses were investigated using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS). Particles emitted during passive degassing activity from the two active vents, Bocca Nuova and North East Crater (BNC and NEC), were identified as silicates, sulfates and halide compounds. In addition to volcanic particles, we found evidences also of geogenic, anthropogenic and marine spray input. The study has shown the robustness of this active biomonitoring technique to collect particles, very useful in active volcanic areas characterized by continuous degassing and often not easily accessible to apply conventional sampling techniques. [ABSTRACT FROM AUTHOR]

Abstract: The studied area is a 130 km long fast spreading graben in Central Greece. Its complex geodynamical setting includes both the presence of a subduction slab at depth responsible for the recent (Quaternary) volcanic activity in the area and the western termination of a tectonic lineament of regional importance (the North-Anatolian fault). A high geothermal gradient is made evident by the presence of many thermal springs with temperatures from 19 to 82 °C, that discharge along the normal faults bordering the graben. In the period 2004–2012, 58 gas and 69 water samples were collected and their chemical and isotopic analysis revealed a wide range of compositions. Two main groups of thermal waters can be distinguished on the basis of their chemical composition. The first, represented by dilute waters (E.C. <0.6 mS/cm) of the westernmost sites, is characterised by the presence of CH4-rich and mixed N2–CH4 gases. The second displays higher salinities (E.C. from 12 to 56 mS/cm) due to mixing with a modified marine component. Reservoir temperatures of 150–160 °C were estimated with cationic geothermometers at the easternmost sites. Along the graben, from west to east, the gas composition changes from CH4- to CO2-dominated through mixed N2–CH4 and N2–CO2 compositions, while at the same time the He isotopic composition goes from typical crustal values (<0.1 R/R A) up to 0.87 R/R A, showing in the easternmost sites a small (3–11%) but significant mantle input. The δ13C values of the CO2-rich samples suggest a mixed origin (mantle and marine carbonates). [Copyright &y& Elsevier]

Recent evidence supports and reinforces the concept that environmental cues may reprogramme somatic cells and change their natural fate. In the present review, we concentrate on environmental reprogramming and fate potency of different epithelial cells. These include stratified epithelia, such as the epidermis, hair follicle, cornea and oesophagus, as well as the thymic epithelium, which stands alone among simple and stratified epithelia, and has been shown recently to contain stem cells. In addition, we briefly discuss the pancreas as an example of plasticity of intrinsic progenitors and even differentiated cells. Of relevance, examples of plasticity and fate change characterize pathologies such as oesophageal metaplasia, whose possible cell origin is still debated, but has important implications as a pre-neoplastic event. Although much work remains to be done in order to unravel the full potential and plasticity of epithelial cells, exploitation of this phenomenon has already entered the clinical arena, and might provide new avenues for future cell therapy of these tissues. [ABSTRACT FROM AUTHOR]

About 120 rainwater samples were collected through a network of five bulk collectors in the area of the Louros basin (Epirus, Greece) during the wet season from October 2008 to August 2009. They were analysed for their isotopic (δD and δ18O) and chemical (H+, Na+, K+, Mg2+, Ca2+, NH4 +, F−, Cl−, Br−, NO3 −, SO4 2−) composition. A local meteoric water line (δD‰=5.80±0.02 δ18O‰+0.02±0.12) and a local isotopic lapse rate (−0.18 δ18O‰/100m) were obtained considering the volume-weighted means of the five sampling sites. These results agree well with those obtained in nearby areas. The chemical composition of the samples allows to identify an almost entirely marine origin for chloride and sodium with decreasing deposition values at increasing distance from the coast. Nitrate and ammonium are almost completely of anthropogenic origin, calcium and potassium are overwhelmingly geogenic, sulphate has a prevailingly anthropogenic origin with a significant marine contribution and magnesium has a mixed marine and soil dust origin. Finally, as for most of the Mediterranean area, rainwater acidity is buffered by the dissolution of the abundant geogenic carbonate aerosol. [ABSTRACT FROM AUTHOR]

Abstract: Passive samplers were used to measure the atmospheric concentrations of SO2 naturally emitted at three volcanoes in Italy (Etna, Vulcano and Stromboli) and of H2S naturally emitted at three volcanic/geothermal areas in Greece (Milos, Santorini and Nisyros). The measured concentrations and dispersion patterns varied with the strength of the source (open conduits or fumaroles), the meteorological conditions and the area topography. At Etna, Vulcano and Stromboli, SO2 concentrations reach values that are dangerous to people affected by bronchial asthma or lung diseases (>1000μgm−3). H2S values measured at Nisyros also exceed the limit considered safe for the same group of people (>3000μgm−3). The data obtained using passive samplers represent time-averaged values over periods from a few days up to 1month, and hence concentrations probably reached much higher peak values that were potentially also dangerous to healthy people. The present study provides evidence of a peculiar volcanic risk associated with tourist exploitation of active volcanic areas. This risk is particularly high at Mt. Etna, where the elderly and people in less-than-perfect health can easily reach areas with dangerous SO2 concentrations via a cableway and off-road vehicles. [Copyright &y& Elsevier]

Methane soil flux measurements have been made in 38 sites at the geothermal system of Sousaki (Greece) with the closed chamber method. Fluxes range from −47.6 to 29 150 mg m day, and the diffuse CH output of the system has been estimated at 19 t a. Contemporaneous CO flux measurements showed a moderate positive correlation between CO and CH fluxes. Comparison of the CO/CH soil flux ratios with the CO/CH ratio of the gases of the main gas manifestations provided evidence for methanotrophic activity within the soil. Laboratory CH consumption experiments confirmed the presence of methanotrophic microorganisms in soil samples collected at Sousaki. Consumption was generally in the range from −4.9 to −38.9 pmolCH h g but could sometimes reach extremely high values (−33 000 pmolCH h g). These results are consistent with recent studies on other geothermal systems that revealed the existence of thermoacidophilic bacteria exerting methanotrophic activity in hot, acid soils, thereby reducing methane emissions to the atmosphere. [ABSTRACT FROM AUTHOR]

Abstract: Chemical and isotopic analyses of the main gas manifestations of the island of Pantelleria (Italy) were used to gain insight on the origin of the released methane. Results indicate that the most probable origin is through abiogenic reactions within the hydrothermal system. Methane and CO2 flux measurements from the soils were made with the accumulation chamber method in an area of about 0.015km2 within the main fumarolic area of the island (Favara Grande). The 23 measurements range from −34 to 3550mgm−2 d−1 for CH4 and from 0.6 to 379gm−2 d−1 for CO2. The relationships between CH4 and CO2 fluxes and the CH4/CO2 ratios in the gases collected between the depths of 25 and 100cm provide evidence for methanotrophic processes within the soils. Methane output for the surveyed area was calculated to be 2.5ta−1 and extrapolated to about 5–10ta−1 for the entire volcanic/hydrothermal system of the island. Previous higher estimates of the CH4 output at Pantelleria (Etiope et al., 2007, J. Volcanol. Geotherm. Res., 165, 76–86) were based on soil CO2 output and CH4/CO2 ratios in fumarolic gases; the present work provides the first direct CH4 flux data and it suggests that methanotrophic activity in the soil could be substantial in reducing the CH4 emission to the atmosphere. [Copyright &y& Elsevier]

Abstract: An extensive geochemical survey of the fluids released by the volcanic/geothermal system of Methana was undertaken. Gases were characterized based on the chemical and isotopic [helium (He) and carbon (C)] analysis of 27 samples. Carbon dioxide soil gas concentration and fluxes were measured at 179 sampling sites throughout the peninsula. Forty samples of thermal and cold groundwaters were also sampled and analysed to characterize the geochemistry of the aquifers. Gases of hydrothermal origin gave a preliminary geothermometric estimate of about 210 °C. The He-isotope composition indicated mantle contributions of up to 40%, and the C-isotope composition of CO2 indicated that it predominantly (>90%) originated from limestone decomposition. The groundwater composition was suggestive of mixing between meteoric and hydrothermally modified sea-water endmembers and water–rock interaction processes limited to simple rock dissolution driven by an increased endogenous CO2 content. All of the thermal manifestations and anomalous degassing areas, although of limited extent, were spatially correlated with the main active tectonic system of the area. The total CO2 output of the volcanic system has been preliminary estimated to be less than 0.05 kg s−1. Although this value is very low compared to those of other volcanic systems, anomalous CO2 degassing at Methana – which is currently restricted to limited areas and at present is the only volcanic risk of the peninsula – is a potential gas hazard that warrants further assessment in future studies. [Copyright &y& Elsevier]

Many studies have assessed the strong influence of volcanic activity on the surrounding environment. This is particularly true for strong gas emitters such as Mt. Etna and Stromboli volcanoes. Among volcanic gases, fluorine compounds are potentially very harmful. Fluorine cycling through rainwater in the above volcanic areas was studied analysing more than 400 monthly bulk samples. Data indicate that only approximately 1% of fluorine emission through the plume is deposited on the two volcanic areas by meteoric precipitations. Although measured bulk rainwater fluorine fluxes are comparable to and sometimes higher than in heavily polluted areas, their influence on the surrounding vegetation is limited. Only annual crops, in fact, show some damage that could be an effect of fluorine deposition, indicating that long-living endemic plant species or varieties have developed some kind of resistance. [Copyright &y& Elsevier]

Turnera carolina, a new species from Chapada das Mesas region in the Brazilian Cerrado, is described and illustrated. The new taxon can be characterized by having internodes up to 5 cm long, leaves with dark spots on both sides, petals that are smaller than the sepals, bracts and calyx that are usually reddish, and an orange corolla. We also present a distribution map, illustrations, field photos, comments on taxonomy, and an identification key to the species of Turnera from Chapada das Mesas National Park and surroundings. [ABSTRACT FROM AUTHOR]

Samples of efflorescences and encrustations of hydrothermal origin were collected at Sousaki (Greece) and analysed for their mineralogical (XRD) and chemical composition. Solutions obtained both from mineralization with HNO 3 and from leaching with deionised water were analysed for major (ICP-OES), minor and trace metals (ICP-MS) and sulfate contents (IC). Results evidence the dependence of the chemical and mineralogical composition on micro-environmental conditions i.e. humidity, oxygen-rich or -poor environment, exposed or sheltered from meteoric agents. In fact, the presence of highly soluble sulfate minerals with elevated contents of many metals (e.g. Mg, Al, Fe, Mn, Cr, Ni, etc.) further underscores the important influence of hydrothermal activity on elements' mobility, whilst the sometimes very high concentrations in toxic elements like Al, Cr, Ni suggest also possible environmental impacts. • The ultramafic rock composition of the area is reflected in the chemistry of the efflorescences and incrustations. • Fumarolic alteration products temporarily stores high quantities of highly soluble elements. • Flushes after dry periods may transport high levels of harmful toxic contaminants. [ABSTRACT FROM AUTHOR]

Background: Genome reduction in intracellular pathogens and endosymbionts is usually compensated by reliance on the host for energy and nutrients. Free-living taxa with reduced genomes must however evolve strategies for generating functional diversity to support their independent lifestyles. An emerging model for the latter case is the Rhodophyta (red algae) that comprises an ecologically widely distributed, species-rich phylum. Red algae have undergone multiple phases of significant genome reduction, including extremophilic unicellular taxa with limited nuclear gene inventories that must cope with hot, highly acidic environments. Results: Using genomic data from eight red algal lineages, we identified 155 spliceosomal machinery (SM)-associated genes that were putatively present in the red algal common ancestor. This core SM gene set is most highly conserved in Galdieria species (150 SM genes) and underwent differing levels of gene loss in other examined red algae (53-145 SM genes). Surprisingly, the high SM conservation in Galdieria sulphuraria coincides with the enrichment of spliceosomal introns in this species (2 introns/gene) in comparison to other red algae (< 0.34 introns/gene). Spliceosomal introns in G. sulphuraria undergo alternatively splicing, including many that are differentially spliced upon changes in culture temperature. Conclusions: Our work reveals the unique nature of G. sulphuraria among red algae with respect to the conservation of the spliceosomal machinery and introns. We discuss the possible implications of these findings in the highly streamlined genome of this free-living eukaryote. [ABSTRACT FROM AUTHOR]

We report three species of Bromeliaceae (Encholirium spectabile Mart. ex Schult. & Schult.f., Pitcairnia burchellii Mez, and Tillandsia bulbosa Hook.) for the first time from Maranhão, northeastern Brazil, based on our fieldwork. Data on species' morphology, taxonomy, ecology, and geographic distribution are included. Our new data add to the knowledge to the flora of Maranhão and expand the distribution of three bromeliad species in Brazil. [ABSTRACT FROM AUTHOR]

Karst hydrosystems represent one of the largest global drinking water resources, but they are extremely vulnerable to pollution. Climate change, high population density, intensive industrial, and agricultural activities are the principal causes of deterioration, both in terms of quality and quantity, of these resources. Samples from 172 natural karst springs were collected in the whole territory of Greece. To identify any geogenic contamination and/or anthropogenic pollution, analyses of their chemical compositions, in terms of major ions and trace elements, were performed and compared to the EU limits for drinking water. Based on chloride content, the collected karst springs were divided into two groups: low-chloride (< 100 mg L−1) and high-chloride content (> 100 mg L−1). An additional group of springs with calcium-sulfate composition was recognised. Nitrate concentrations were always below the EU limit (50 mg L−1), although some springs presented elevated concentrations. High contents in terms of trace elements, such as B, Sr, As, and Pb, sometimes exceeding the limits, were rarely found. The Greek karst waters can still be considered a good quality resource both for human consumption and for agriculture. The main issues derive from seawater intrusion in the aquifers along the coasts. Moreover, the main anthropogenic pollutant is nitrate, found in higher concentrations mostly in the same coastal areas where human activities are concentrated. Finally, high levels of potentially harmful trace elements (e.g. As, Se) are very limited and of natural origin (geothermal activity, ore deposits, etc.). [ABSTRACT FROM AUTHOR]

The study area is close to the boundary of three tectonic plates (Anatolian, Arabian, and African plates) and is characterized by important tectonic lineaments, which consist mainly of the Dead Sea Fault (DSF), the Karasu Fault, and the East Anatolian Fault (EAF) systems. To understand the origin of soil gas emanation and its relationships with the tectonics of the Amik Basin (Hatay), a detailed soil gas sampling was systematically performed. Together with CO 2 flux measurements, > 220 soil gas samples were analyzed for Rn and CO 2 concentrations. The distribution of soil Rn (kBq/m 3 ), CO 2 concentration (ppm), and CO 2 flux (g/m 2 /day) in the area appears as a point source (spot) and/or diffuses (halo) anomalies along the buried faults/fractures due to crustal leaks. The results revealed that Rn and CO 2 concentrations in the soil gas show anomalous values at the specific positions in the Amik Basin. The trace of these anomalous values is coincident with the N-S trending DSF. CO 2 is believed to act as a carrier for Rn gas. Based on the Rn and CO 2 concentrations of soil gases, at least three gas components are required to explain the observed variations. In addition to the atmospheric component, two other gas sources can be recognized. One is the deep crust component, which exhibits high Rn and CO 2 concentrations, and is considered the best indicator for the surface location of fault/fracture zones in the region. The other component is a shallower gas source with high Rn concentration and low CO 2 concentration. Moreover, He isotopic compositions of representative samples vary from 0.94 to 0.99 Ra, illustrating that most samples have a soil air component and may have mixed with some crustal component, without significant input of the mantle component. Based on the repeated measurements at a few sites, soil gas concentrations at the same site were observed to be higher in 2014 than in 2013, which may be associated with the activity of the DSF in 2013–2014. This suggests that soil gas variations at fault zone are closely related to the local crustal stress, and hence are suitable for monitoring fault activities. [ABSTRACT FROM AUTHOR]

Cyanidioschyzon merolae ( C. merolae ) is an acidophilic red alga growing in a naturally low carbon dioxide (CO 2 ) environment. Although it uses a ribulose 1,5-bisphosphate carboxylase/oxygenase with high affinity for CO 2 , the survival of C. merolae relies on functional photorespiratory metabolism. In this study, we quantified the transcriptomic response of C. merolae to changes in CO 2 conditions. We found distinct changes upon shifts between CO 2 conditions, such as a concerted up-regulation of photorespiratory genes and responses to carbon starvation. We used the transcriptome data set to explore a hypothetical CO 2 concentrating mechanism in C. merolae , based on the assumption that photorespiratory genes and possible candidate genes involved in a CO 2 concentrating mechanism are co-expressed. A putative bicarbonate transport protein and two α-carbonic anhydrases were identified, which showed enhanced transcript levels under reduced CO 2 conditions. Genes encoding enzymes of a PEPCK-type C 4 pathway were co-regulated with the photorespiratory gene cluster. We propose a model of a hypothetical low CO 2 compensation mechanism in C. merolae integrating these low CO 2 -inducible components. [ABSTRACT FROM AUTHOR]

The Dead Sea Transform (DST) fault system, where a lateral displacement between the African and Arabian plates occurs, is characterised by anomalous heat flux in the Israeli area close to the border with Syria and Jordan. The concentration of He and CO 2 , and isotopic composition of He and total dissolved inorganic carbon were studied in cold and thermal waters collected along the DST, in order to investigate the source of volatiles and their relationship with the tectonic framework of the DST. The waters with higher temperature (up to 57.2 °C) are characterised by higher amounts of CO 2 and helium (up to 55.72 and 1.91 ∗ 10 − 2 cc l − 1 , respectively). Helium isotopic data (R/Ra from 0.11 to 2.14) and 4 He/ 20 Ne ratios (0.41–106.86) show the presence of deep-deriving fluids consisting of a variable mixture of mantle and crust end-members, with the former reaching up to 35%. Carbon isotope signature of total dissolved carbon from hot waters falls within the range of magmatic values, suggesting the delivery of deep-seated CO 2 . The geographical distribution of helium isotopic data and isotopic carbon (CO 2 ) values coupled with (CO 2 / 3 He ratios) indicate a larger contribution of mantle-derived fluids affecting the northern part of the investigated area, where the waters reach the highest temperature. These evidences suggest the occurrence of a favourable tectonic framework, including a Moho discontinuity up-rise and/or the presence of a deep fault system coupled with the recent magmatic activity recognised in the northern part of Israel. [ABSTRACT FROM AUTHOR]

This study is focused on the (micro)biogeochemical features of two close geothermal sites ( FAV1 and FAV2), both selected at the main exhalative area of Pantelleria Island, Italy. A previous biogeochemical survey revealed high CH4 consumption and the presence of a diverse community of methanotrophs at FAV2 site, whereas the close site FAV1 was apparently devoid of methanotrophs and recorded no CH4 consumption. Next-Generation Sequencing ( NGS) techniques were applied to describe the bacterial and archaeal communities which have been linked to the physicochemical conditions and the geothermal sources of energy available at the two sites. Both sites are dominated by Bacteria and host a negligible component of ammonia-oxidizing Archaea (phylum Thaumarchaeota). The FAV2 bacterial community is characterized by an extraordinary diversity of methanotrophs, with 40% of the sequences assigned to Methylocaldum, Methylobacter (Gammaproteobacteria) and Bejerickia (Alphaproteobacteria); conversely, a community of thermo-acidophilic chemolithotrophs ( Acidithiobacillus, Nitrosococcus) or putative chemolithotrophs ( Ktedonobacter) dominates the FAV1 community, in the absence of methanotrophs. Since physical andchemical factors of FAV1, such as temperature and pH, cannot be considered limiting for methanotrophy, it is hypothesized that the main limiting factor for methanotrophs could be high NH4+ concentration. At the same time, abundant availability of NH4+ and other high energy electron donors and acceptors determined by the hydrothermal flux in this site create more energetically favourable conditions for chemolithotrophs that outcompete methanotrophs in non-nitrogen-limited soils. [ABSTRACT FROM AUTHOR]

We investigated the geochemical features of the fluids circulating over the Amik Basin (SE Turkey–Syria border), which is crossed by the Northern extension of the DSF (Dead Sea Fault) and represents the boundary area of three tectonic plates (Anatolian, Arabian and African plates). We collected 34 water samples (thermal and cold from natural springs and boreholes) as well as 8 gas samples (bubbling and gas seepage) besides the gases dissolved in the sampled waters. The results show that the dissolved gas phase is a mixture of shallow (atmospheric) and deep components either of mantle and crustal origin. Coherently the sampled waters are variable mixtures of shallow and deep ground waters, the latter being characterised by higher salinity and longer residence times. The deep groundwaters (from boreholes deeper than 1000 m) have a CH 4 -dominated dissolved gas phase related to the presence of hydrocarbon reservoirs. The very unique tectonic setting of the area includes the presence of an ophiolitic block outcropping in the westernmost area on the African Plate, as well as basalts located to the North and East on the Arabic Plate. The diffuse presence of CO 2 -enriched gases, although diluted by the huge groundwater circulation, testifies a regional degassing activity. Fluids circulating over the ophiolitic block are marked by H 2 -dominated gases with abiogenic methane and high-pH waters. The measured 3 He/ 4 He isotopic ratios display contributions from both crustal and mantle-derived sources over both sides of the DSF. Although the serpentinization process is generally independent from mantle-type contribution, the recorded helium isotopic ratios highlight variable contents of mantle-derived fluids. Due to the absence of recent volcanism over the western side of the basin (African Plate), we argue that CO 2 -rich volatiles carrying mantle-type helium and enriched in heavy carbon, are degassed by deep-rooted regional faults rather than from volcanic sources. [ABSTRACT FROM AUTHOR]

The development of a resilient society is a major challenge for growing human population faced with abundant natural hazards. During and after the May 22, 2021 eruption of Nyiragongo, the local population was surprised and scared by the subsequent seismicity and associated surface fracturing, coupled with the alert of a possible new eruptive vent opening in Goma (Democratic Republic of Congo) and/or Gisenyi (Rwanda). The creation of a toll-free phone number enabled the population to record fractures and gas/thermal anomalies affecting the area. Such work was fundamental in enabling scientists and authorities to assess the associated risks. Crucially, gas data showed that the degassing through fractures did not represent direct transfer of magmatic volatiles but was more likely of superficial origin. Surprisingly, this participatory work revealed that the first fractures appeared several weeks before the eruption and their opening was not detected by the monitoring system. This firmly underlines the need for scientists to anchor citizen science in monitoring strategies. [ABSTRACT FROM AUTHOR]

Highlights: [•] Isotopic composition of precipitation and groundwater in Sicily (Italy). [•] Isotopic data processing for hydrogeological purpose. [•] GIS mapping of isotopic data. [Copyright &y& Elsevier]

The thymus develops from the third pharyngeal pouch of the anterior gut and provides the necessary environment for thymopoiesis (the process by which thymocytes differentiate into mature T lymphocytes) and the establishment and maintenance of self-tolerance. It contains thymic epithelial cells (TECs) that form a complex three-dimensional network organized in cortical and medullary compartments, the organization of which is notably different from simple or stratified epithelia. TECs have an essential role in the generation of self-tolerant thymocytes through expression of the autoimmune regulator Aire, but the mechanisms involved in the specification and maintenance of TECs remain unclear. Despite the different embryological origins of thymus and skin (endodermal and ectodermal, respectively), some cells of the thymic medulla express stratified-epithelium markers, interpreted as promiscuous gene expression. Here we show that the thymus of the rat contains a population of clonogenic TECs that can be extensively cultured while conserving the capacity to integrate in a thymic epithelial network and to express major histocompatibility complex class II (MHC II) molecules and Aire. These cells can irreversibly adopt the fate of hair follicle multipotent stem cells when exposed to an inductive skin microenvironment; this change in fate is correlated with robust changes in gene expression. Hence, microenvironmental cues are sufficient here to re-direct epithelial cell fate, allowing crossing of primitive germ layer boundaries and an increase in potency. [ABSTRACT FROM AUTHOR]

Major ion content of 37 wet-only rainwater samples collected on the southern flank of Mount Etna volcano was investigated. Measured pH values range from 3.80 to 7.22 and display a positive correlation with Ca2 + and an inverse correlation with NO3-, suggesting that anthropogenic NOx are the most effective acidifying agents while Ca, likely as solid CaCO3, is the prevailing proton acceptor. Na/Cl ratios indicate a dominant marine origin for both species, while K, mg and Ca contents point to additional sources (soil dust, fertilisers etc.). Nitrate and sulphate concentrations display a nearly constant ratio indicating a common anthropogenic origin, and only a few samples are characterised by sulphate excess. The analysis of time series reveals a good correlation between the excess sulphate in rainwater and SO2 fluxes from the summit craters plume. Non sea salt chloride contents show also a significant correlation with volcanic activity indicating a magmatic sulphur and chloride contribution to rainwater. Meteoric flux estimations point to a prevailing magmatic origin for sulphur in the collected rainwaters while sea spray is the main source of chlorine. [ABSTRACT FROM AUTHOR]

Nisyros Island (Greece) is an active volcano hosting a high-enthalpy geothermal system. During June 2013, an extensive survey on Hg concentrations in different matrices (fumarolic fluids, atmosphere, soils, and plants) was carried out at the Lakki Plain, an intracaldera area affected by widespread soil and fumarolic degassing. Concentrations of gaseous elemental mercury (GEM), together with H2S and CO2, were simultaneously measured in both the fumarolic emissions and the atmosphere around them. At the same time, 130 samples of top soils and 31 samples of plants (Cistus creticus and salvifolius and Erica arborea and manipuliflora) were collected for Hg analysis. Mercury concentrations in fumarolic gases ranged from 10,500 to 46,300 ng/m3, while Hg concentrations in the air ranged from high background values in the Lakki Plain caldera (10-36 ng/m3) up to 7100 ng/m3 in the fumarolic areas. Outside the caldera, the concentrations were relatively low (2-5 ng/m3). The positive correlation with both CO2 and H2S in air highlighted the importance of hydrothermal gases as carrier for GEM. On the other hand, soil Hg concentrations (0.023-13.7 μg/g) showed no significant correlations with CO2 and H2S in the soil gases, whereas it showed a positive correlation with total S content and an inverse one with the soil pH, evidencing the complexity of the processes involving Hg carried by hydrothermal gases while passing through the soil. Total Hg concentrations in plant leaves (0.010-0.112 μg/g) had no direct correlation with soil Hg, with Cistus leaves containing higher values of Hg with respect to Erica. Even though GEM concentrations in the air within the caldera are sometimes orders of magnitude above the global background, they should not be considered dangerous to human health. Values exceeding the WHO guideline value of 1000 ng/m3 are very rare (<0.1%) and only found very close to the main fumarolic vents, where the access to tourists is prohibited. [ABSTRACT FROM AUTHOR]

We report the first records of Tillandsia kegeliana, T. loliacea, T. paraensis, T. parvispica, T. recurvata, and T. tenuifolia for Maranhão, Brazil. These species were collected in the Amazonian and Cerrado biomes. This work adds new knowledge to the flora of Maranhão and extends the distribution of these species within Brazil. [ABSTRACT FROM AUTHOR]

Members of Oncidiinae are widely known for their interactions with oil-collecting bees that explore lipophilic secretions on flowers. They may also be pollinated through food deception and the offering of nectar. Although data on breeding systems are available for many Oncidiinae orchids, little is known about the reproductive strategies in Rodriguezia, a neotropical genus of ca. 55 species. In this paper, we explore the reproductive biology of two species of Rodriguezia with distinctive morphologies: R. decora and R. lanceolata. Floral features, spectral reflectance, pollinators and pollination mechanisms, and breeding systems were studied. Both species are scentless and produce nectar as a reward. Floral nectar is secreted by a gland at the base of the labellum and stored into the sepaline spur. Rodriguezia decora reflects mainly in the blue and red regions of the light spectrum, while R. lanceolata reflects in the red region. Rodriguezia decora is exclusively visited and pollinated by butterflies, while Trochilidae hummingbirds are the pollinators of R. lanceolata. Pollinaria attach to the upper third of the proboscis of butterflies (R. decora), and to the bill of hummingbirds (R. lanceolata), during the collection of nectar from the spur. Both Rodriguezia species are self-sterile. Flower features and floral reflectance support the occurrence of psychophily in R. decora and ornithophily in R. lanceolata. [ABSTRACT FROM AUTHOR]

Methylglyoxal (MGO) and glyoxal (GO) are toxic reactive carbonyl species generated as by-products of glycolysis. The pre-emption pathway for detoxification of these products, the glyoxalase (GLX) system, involves two consecutive reactions catalyzed by GLXI and GLXII. In Arabidopsis thaliana , the GLX system is encoded by three homologs of GLXI and three homologs of GLXII , from which several predicted GLXI and GLXII isoforms can be derived through alternative splicing. We identified the physiologically relevant splice forms using sequencing data and demonstrated that the resulting isoforms have different subcellular localizations. All three GLXI homologs are functional in vivo, as they complemented a yeast GLXI loss-of-function mutant. Efficient MGO and GO detoxification can be controlled by a switch in metal cofactor usage. MGO formation is closely connected to the flux through glycolysis and through the Calvin Benson cycle; accordingly, expression analysis indicated that GLXI is transcriptionally regulated by endogenous sugar levels. Analyses of Arabidopsis loss-of-function lines revealed that the elimination of toxic reactive carbonyl species during germination and seedling establishment depends on the activity of the cytosolic GLXI;3 isoform. The Arabidopsis GLX system involves the cytosol, chloroplasts, and mitochondria, which harbor individual components that might be used at specific developmental stages and respond differentially to cellular sugar status. [ABSTRACT FROM AUTHOR]

Fractions of the volatiles ascending from magma chambers meet groundwaters flowing away from the volcano summit and are carried to great distance as dissolved gases. The complex interactions between ascending magmatic volatiles, tectonic structures, heterogeneities in rock permeability and flow lines of aquifers deeply affect the dispersion of the dissolved species. Studying the spatial distribution of such species can therefore provide valuable information on the circulation of fluids inside volcanic edifices. Our study focussed on the composition of dissolved inert gases (He, Ne and N 2 ) and He isotope ratio ( 3 He/ 4 He) in groundwaters circulating at Mt Etna volcano (Italy), because the concentrations of these species differ markedly between magmatic and shallow (crustal and atmospheric) sources, and they do not interact chemically with rocks. We identified groundwaters that flow through anomalously degassing areas associated with clearly evident or known tectonic structures. These waters show a typically magmatic He isotope composition (high 3 He/ 4 He ratios) and high proportions of dissolved magmatic gases (He and CO 2 ) compared to the atmospheric ones (Ne and N 2 ). Downstream of the degassing structures, along the hydrological outflows, we found groundwaters that are progressively enriched in atmospheric-derived gases (Ne and N 2 ) and exhibited lower 3 He/ 4 He ratios. On this basis, we set up a model of unidimensional dispersion-advection of inert volatile solutes, coupled with a two-layer model for the dynamic exchange of volatiles through the aquifer–atmosphere interface. The model is able to quantitatively explain the progressive dilution of the magmatic signal over distances of several kilometres from the source location of the anomaly towards the final part of the flow lines at the coast. Typical hydrogeological parameters such as the flow velocity, rock permeability and rate of air–groundwater interaction can be constrained, and underground pathways of waters can be identified. Waters that are anomalously rich in magmatic tracers with respect to their peripheral position along the flow lines reflect arrival of deep gases from below, and they therefore offer a powerful tool for revealing hidden tectonic structures. [ABSTRACT FROM AUTHOR]

In this study, hydrogen sulfide (H 2 S) measurements in air carried out using (a) passive/diffusive samplers (Radiello ® traps) and (b) a high-frequency (60 s) real-time analyzer (Thermo ® 450i) were compared in order to evaluate advantages and limitations of the two techniques. Four different sites in urban environments (Florence, Italy) and two volcanic areas characterized by intense degassing of H 2 S-rich fluids (Campi Flegrei and Vulcano Island, Italy) were selected for such measurements. The concentrations of H 2 S generally varied over 5 orders of magnitude (from 10 −1 –10 3 μg/m 3 ), the H 2 S values measured with the Radiello ® traps (H 2 S R ) being significantly higher than the average values measured by the Thermo ® 450i during the trap exposure (H 2 S Ta ), especially when H 2 S was <30 μg/m 3 . To test the reproducibility of the Radiello ® traps, 8 passive/diffusive samplers were contemporaneously deployed within an 0.2 m 2 area in an H 2 S-contaminated site at Mt. Amiata (Tuscany, Italy), revealing that the precision of the H 2 S R values was ±49%. This large uncertainty, whose cause was not recognizable, is to be added to that related to the environmental conditions (wind speed and direction, humidity, temperature), which are known to strongly affect passive measurements. The Thermo ® 450i analyzer measurements highlighted the occurrence of short-term temporal variations of the H 2 S concentrations, with peak values (up to 5732 μg/m 3 ) potentially harmful to the human health. The Radiello ® traps were not able to detect such temporal variability due to their large exposure time. The disagreement between the H 2 S R and H 2 S Ta values poses severe concerns for the selection of an appropriate methodological approach aimed to provide an accurate measurement of this highly toxic air pollutant in compliance with the WHO air quality guidelines. Although passive samplers may offer the opportunity to carry out low-cost preliminary surveys, the use of the high-frequency H 2 S analyzer is preferred when an accurate assessment of air quality is required. In fact, the latter provides precise real-time measurements for a reliable estimation of the effective exposure to hazardous H 2 S concentrations, giving insights into the mechanisms regulating the dispersion of this air pollutant in relation to the meteorological parameters. [ABSTRACT FROM AUTHOR]

Geochemical behaviour of rare earth elements (REE), Zr, and Hf was investigated in CO 2 -rich waters circulating in Pantelleria Island also including ‘Specchio di Venere’ Lake within a calderic depression. A wide range of total dissolved REE concentrations was found (2.77–12.07 nmol L − 1 ), with the highest contents in the lake. The main REE complexes in the CO 2 -rich waters are [REE(CO 3 ) 2 ] − and [REECO 3 ] + , showing changeable proportions as a function of pH. The REE normalized to post-Archean Australian Shale (PAAS) showed similar features with heavy REE (HREE) enrichments in CO 2 -rich waters collected from springs and wells, whereas a different REE pattern was found in the ‘Specchio di Venere’ Lake water with middle REE (MREE) enrichments. The PAAS normalized concentration ratios (LREE/HREE) N and (MREE/HREE) N in waters are < 1, except for the lake water in which (MREE/HREE) N > 1. Positive Eu anomalies were found in the investigated waters owing to water–rock interactions with less evolved host rocks. Ce anomalies as a function of Eh values were recognized, with the highest Ce anomaly occurring in the lake water with respect to the CO 2 -rich waters. The Y/Ho and Zr/Hf molar ratios are higher in the investigated waters (except for lake water) than that in the local rocks, with values ranging from 35.4 to 77.9 and from 76.3 to 299, respectively. The precipitation of authigenic phases was considered to be responsible for the increase in the Y/Ho and Zr/Hf ratios owing to enhanced Hf and Ho removal with respect to Zr and Y. The REE patterns in the lake water show a similar shape (MREE-enriched and a positive Ce anomaly) as those found in the settling dust and in the desert varnish coating of the rocks in arid environments, which mainly contain Fe- and Mn-oxyhydroxides and clay minerals. Similarly, Y/Ho and Zr/Hf ratios in the ‘Specchio di Venere’ Lake (35.4 and 76.3, respectively) show a desert varnish signature. These data, coupled with the presence of iron oxyhydroxides and phyllosilicates in the shallowest water layer of the ‘Specchio di Venere’ Lake, verify the aeolian input from the Sahara Desert. [ABSTRACT FROM AUTHOR]

The geochemical behaviour of Rare Earth Elements, Zr and Hf was investigated in the thermal waters of Nevado del Ruiz volcano system. A wide range of pH, between 1.0 and 8.8, characterizes these fluids. The acidic waters are sulphate dominated with different Cl/SO 4 ratios. The important role of the pH and the ionic complexes for the distribution of REE, Zr and Hf in the aqueous phase was evidenced. The pH rules the precipitation of authigenic Fe and Al oxyhydroxides producing changes in REE, Zr, Hf amounts and strong anomalies of Cerium. The precipitation of alunite and jarosite removes LREE from the solution, changing the REE distribution in acidic waters. Y–Ho and Zr–Hf (twin pairs) have a different behaviour in strong acidic waters with respect to the water with pH near-neutral. Yttrium and Ho behave as Zr and Hf in waters with pH near neutral-to-neutral, showing super-chondritic ratios. The twin pairs showed to be sensitive to the co-precipitation and/or adsorption onto the surface of authigenic particulate (Fe-, Al-oxyhydroxides), suggesting an enhanced scavenging of Ho and Hf with respect to Y and Zr, leading to superchondritic values. In acidic waters, a different behaviour of twin pairs occurs with chondritic Y/Ho ratios and sub-chondritic Zr/Hf ratios. For the first time, Zr and Hf were investigated in natural acidic fluids to understand the behaviour of these elements in extreme acidic conditions and different major anion chemistry. Zr/Hf molar ratio changes from 4.75 to 49.29 in water with pH < 3.6. In strong acidic waters the fractionation of Zr and Hf was recognized as function of major anion contents (Cl and SO 4 ), suggesting the formation of complexes leading to sub-chondritic Zr/Hf molar ratios. [ABSTRACT FROM AUTHOR]

Abstract: This study reports on the first quantitative assessment of the geochemical cycling of volcanogenic elements, from their atmospheric release to their deposition back to the ground. Etna’s emissions and atmospheric depositions were characterised for more than 2years, providing data on major and trace element abundance in both volcanic aerosols and bulk depositions. Volcanic aerosols were collected from 2004 to 2007, at the summit vents by conventional filtration techniques. Precipitation was collected, from 2006 to 2007, in five rain gauges, at various altitudes around the summit craters. Analytical results for volcanic aerosols showed that the dominant anions were S, Cl, and F, and that the most abundant metals were K, Ca, Mg, Al, Fe, and Ti (1.5–50μgm−3). Minor and trace element concentrations ranged from about 0.001 to 1μgm−3. From such analysis, we derived an aerosol mass flux ranging from 3000 to 8000ta−1. Most analysed elements had higher concentrations close to the emission vent, confirming the prevailing volcanic contribution to bulk deposition. Calculated deposition rates were integrated over the whole Etna area, to provide a first estimate of the total deposition fluxes for several major and trace elements. These calculated deposition fluxes ranged from 20 to 80ta−1 (Al, Fe, Si) to 0.01–0.1ta−1 (Bi, Cs, Sc, Th, Tl, and U). Comparison between volcanic emissions and atmospheric deposition showed that the amount of trace elements scavenged from the plume in the surrounding of the volcano ranged from 0.1% to 1% for volatile elements such as As, Bi, Cd, Cs, Cu, Tl, and from 1% to 5% for refractory elements such as Al, Ba, Co, Fe, Ti, Th, U, and V. Consequently, more than 90% of volcanogenic trace elements were dispersed further away, and may cause a regional scale impact. Such a large difference between deposition and emission fluxes at Mt. Etna pointed to relatively high stability and long residence time of aerosols in the plume. [Copyright &y& Elsevier]

Abstract: The significant amounts of selenium (Se) emitted by volcanoes may have important impact on human health due to the narrow range between nutrition requirement and toxic effects for living organisms upon Se exposure. Although soils play a key role in determining the level in food and water and thereby human health, little is known about the behaviour of Se in volcanic soils. In this work we evaluated the Se release during rainwater–soil interaction under controlled conditions using soils collected on the flanks of Etna volcano and synthetic rain. Selenium concentrations in soil leachate solutions displayed a spatial distribution, which cannot be explained by plume deposition, total Se soil concentrations or the presence of Fe oxides. Instead, Al compounds and to a minor extent SOM were identified as the active phases controlling the selenate mobilization during interaction with sulphate-containing rainwater. This shows the importance of soils as reactive interfaces. Selenium is mobilized when volcanic-derived acid rain interacts with poorly developed soils close to the crater. This geogenic process might influence the chemical composition of groundwater and as a result, human health. [Copyright &y& Elsevier]

Abstract: Ischia volcano, in Central Italy, has long been known for its copious surface hydrothermal manifestations, signs of a pervasive circulation of hot fluids in the subsurface. Because of the significant chemical heterogeneity of fumarolic gas discharges and hot spring discharges, evidences of a complex hydrothermal setting, a definite model of fluid circulation at depth is currently unavailable, in spite of the several previous efforts. Here, we report on the chemical and isotopic composition of 120 groundwater samples, collected during several sampling surveys from 2002 to 2007. The acquired data suggest that the composition of surface manifestations reflect contributions from meteoric water, sea water, and thermal fluids rising from two distinct hydrothermal reservoir, with equilibrium temperatures of respectively ~150 °C and ~270 °C, and depths of 150–300 m and >300 m (but possibly >1000 m). We also make use of an isotopic characterization of the dissolved gas phase in thermal waters to demonstrate that the Ischia hydrothermal system is currently supplied by a deep-rising gas component (DGC), characterized by CO2 ~97.7±1.2 vol.% (on a water-free basis), δ 13CCO2 =−3.51±0.9‰, and helium isotopic ratio of about 3.5 Ra (3He/4He ratio normalized to the air ratio, R a), likely magmatic in origin. An assessment of the thermal budget for Ischia hydrothermal system is also presented, in the attempt to derive a first estimate of the size and rate of degassing of the magmatic reservoir feeding the gas emissions. We calculate that a heat flow of about 153–222 MW presently drives hydrothermal circulation on the island, which we suggest is supplied in convective form (e.g., by the ascent of a high-T magmatic vapour phase) by complete degassing of 2.2–3.3·107 m3 yr−1 of trachytic magma (with ~2.1 wt.% dissolved H2O content). If extrapolated to entire period of quiescence lasting since the Arso eruption in 1302 A.D., this volume corresponds to 1.6–2.3·1010 m3 of magma degassed in about 700 years of quiescent activity. [Copyright &y& Elsevier]

Abstract: Quantifying the contribution of volcanism to global mercury (Hg) emissions is important to understand the pathways and the mechanisms of Hg cycling through the Earth''s geochemical reservoirs and to assess its environmental impacts. While previous studies have suggested that degassing volcanoes might contribute importantly to the atmospheric budget of mercury, little is known about the amount and behaviour of Hg in volcanic aquifers. Here we report on detailed investigations of both the content and the speciation of mercury in aquifers of active volcanoes in Italy and Guadeloupe Island (Lesser Antilles). In the studied groundwaters, total Hg (THg) concentrations range from 10 to 500 ng/l and are lower than the 1000 ng/l threshold value for human health protection fixed by the World Health Organization [WHO (1993): WHO Guidelines for Drinking Water Quality- http://www.who.int/water_sanitation_health/GDWQ/index.htlm]. Positive co-variations of (THg) with sulphate indicate that Hg-SO4-rich acid groundwaters receive a direct input of magmatic/hydrothermal gases carrying mercury as Hg0 (gas). Increasing THg in a volcanic aquifer could thus be a sensitive tracer of magmatic gas input prior to an eruption. Since the complex behaviour and toxicity of mercury in waters depend on its chemical speciation, we carefully determined the different aqueous forms of this element in our samples. We find that dissolved elemental Hg0 (aq) and particulate-bound Hg (HgP) widely prevail in volcanic aquifers, in proportions that highlight the efficiency of Hg adsorption onto colloidal particles. Moreover, we observe that dissolved Hg0 aq and Hg(II) forms coexist in comparable amount in most of the waters, in stark contrast to the results of thermodynamic equilibrium modelling. Therefore, chemical equilibrium between dissolved mercury species in volcanic waters is either prevented by natural kinetic effects or not preserved in collected waters due to sampling/storage artefacts. Finally, we provide a first quantitative comparison of the relative intensity of aqueous transport and atmospheric emissions of mercury at Mount Etna, a very active basaltic volcano. [Copyright &y& Elsevier]

There is an urgent need to better constrain the global rates of mercury degassing from natural sources, including active volcanoes. Hitherto, estimates of volcanic fluxes have been limited by the poorly determined speciation of Hg in volcanic emissions. Here, we present a systematic characterisation of mercury partitioning between gaseous (Hg(g)) and particulate (Hg(p)) forms in the volcanic plume of Mount Etna, the largest open-vent passively degassing volcano on Earth. We demonstrate that mercury transport is predominantly in the gas phase, with a mean Hg(p)/Hg(g) ratio of ∼0.01 by mass. We also present the first simultaneous measurement of divalent gaseous mercury () and total gaseous mercury (Hg(g)) in a volcanic plume, which suggests that is the prevalent form of mercury in this context. These data are supported by the results of model simulations, carried out with HSC thermodynamic software. Based on a mean “bulk plume” Hg/SO2 mass ratio of 8.7×10−6, and a contemporaneous volcanic SO2 flux of 0.8Mtyr−1, we estimate an Hg emission rate from Mt. Etna during passive degassing of 5.4tyr−1 (range, 1.1–10tyr−1). This corresponds to ∼0.6% of global volcanic Hg emissions, and about 5% of Hg released from industrial activities in the Mediterranean area. [Copyright &y& Elsevier]

Abstract: This paper documents arsenic concentrations in 157 groundwater samples from the island of Ischia and the Phlegrean Fields, two of the most active volcano-hosted hydrothermal systems from the Campanian Volcanic Province (Southern Italy), in an attempt to identify the environmental conditions and mineral-solution reactions governing arsenic aqueous cycling. On Ischia and in the Phlegrean Fields, groundwaters range in composition from NaCl brines, which we interpret as the surface discharge of deep reservoir fluids, to shallow-depth circulating fluids, the latter ranging from acid-sulphate steam-heated to hypothermal, cold, bicarbonate groundwaters. Arsenic concentrations range from 1.6 to 6900 μg·l−1 and from 2.6 to 3800 μg·l−1 in the Phlegrean Fields and on Ischia, respectively. They increase with increasing water temperature and chlorine contents, and in the sequence bicarbonate groundwaters

New geochemical data on dissolved major and minor constituents in 276 groundwater samples from Etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation. This topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area. Multivariate statistical analysis reveal 3 sources of solutes: (a) the leaching of the host basalt, driven by the dissolution of magma-derived CO2; (b) mixing processes with saline brines rising from the sedimentary basement below Etna; (c) contamination from agricultural and urban wastewaters. The last process, highlighted by increased concentrations of SO4, NO3, Ca, F and PO4, is more pronounced on the lower slopes of the volcanic edifice, associated with areas of high population and intensive agriculture. However, this study demonstrates that natural processes (a) and (b) are also very effective in producing highly mineralised waters, which in turn results in many constituents (B, V, Mg) exceeding maximum admissible concentrations for drinking water. [Copyright &y& Elsevier]

Monogenetic eruptions are the most common volcanic activity in the world. However, unrest monitoring data are scarce due to the long intervening quiescence periods. This study analyzes unrest signals recorded in one of the largest monogenetic fields in the Canary Islands, Cumbre Vieja (La Palma). Two seismic swarms were registered in October 2017 and February 2018 with b-values of 1.6 ± 0.1 and 2.3 ± 0.2 respectively suggesting an intense magmatic fluids contribution, gas and/or magma. Both swarms were linked to changes in gas emissions. Increases in hydrogen concentration, and (R/R a) c up to 7.52 ± 0.05, were recorded before the first swarm, at the sampling point closest to where seismicity was located, indicating a deep gas input. After the second swarm, increases in (R/R a) c and thoron soil concentration were recorded at two locations. This dataset is compatible with a stalled magmatic intrusion at ca. 25 km depth, with an estimated volume between 5.5·10−4 km3 and 3·10−2 km3. • Geophysical and geochemical signals recorded at La Palma suggest a reawakening of Cumbre Vieja. • Two seismic swarms with high b-value point to a magmatic fluids contribution. • Increases in δ13C-CO 2 and (R/R a) c were recorded close where seismicity was located. • A slight eastward magma migration is suggested by geochemical and geophysical data. • An increase in soil thoron concentration was recorded at two sites after the second swarm. [ABSTRACT FROM AUTHOR]