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Volcanic and geothermal systems significantly contribute to the input of volatile contaminants, such as mercury and hydrogen sulfide, into the atmosphere. Mercury has a strong environmental impact. In the atmosphere the prevalent elemental form is Hg0 (~98 %), whose main physical-chemical features are: high volatility, low solubility and chemical inertness. Hydrogen sulfide (H2S), one of the most abundant gas compounds in volcanic fluids, is highly poisoning and corrosive and unpleasantly smells of rotten eggs. Measurements of Hg0 and H2S concentrations in air are commonly performed by means of passive samplers. However, real-time measurements, coupled with monitoring of local atmospheric conditions, are strongly recommended for a reliable reconstruction of the dispersion dynamics once such contaminants are discharged in air. In this paper, a new real-time measurement method for Hg0 and H2S is presented. A portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) and a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i) were used for Hg0 and H2S measurements, respectively. These instruments were synchronized and set to high-frequency acquisition. Measurements were carried out along transects at an average speed 60 ng/m3 and >2,100 μg/m3, respectively), suggests that these gases were discharged from both fumaroles and diffuse degassing from the crater bottom. At Mt. Amiata, the maximum Hg0 and H2S concentrations (>100 ng/m3 and >35 μg/m3, respectively) were recorded close to the geothermal power plants of Piancastagnaio. According to detailed dot-maps constructed on the basis of the measured values, as expected, wind was the main environmental parameter able to control the behavior and the dispersion halo of the Hg0- and H2S-rich plumes emitted from the contaminant sources.

Like other geodynamically active areas, Greece is affected by a large number of geogenic gas manifestations. These occur either in form of point sources (fumaroles, mofettes, bubbling gases) or as diffuse emanations. We produced a first catalogue of the geogenic gas manifestations of Greece also considering few literature data. Collected samples were analysed for their chemical (He, Ne, Ar, O2, N2, H2, H2S, CO, CH4 and CO2) and isotopic composition (He, C and N). Most of the sampled gas manifestation are found along the South Aegean active volcanic arc (32 sites) and in the majority they belong to the CO2 dominated group. Very few gas manifestations, N2- or CH4- dominated, are found along the most external units of the Hellenides orogen (Apulia domain - W and SW Greece), where generally compressive or transpersive tectonic prevails. On the contrary, gas manifestations (mainly CO2- dominated) are widespread along northern Greece (28 sites) and along Sperchios basin - north Evia graben (12 sites) which are characterised by extensional tectonic. Geogenic gases, apart from having important influences on the global climate, could have strong impact on human health. Gas hazard is often disregarded because fatal episodes are often not correctly attributed. Geodynamic active areas release geogenic gases for million years over wide areas and the potential risks should not be disregarded. A preliminary estimation of the gas hazard has been made for the last 20 years considering the whole population of Greece. In this period at least 2 fatal episodes with a total of 3 victims could be certainly attributed to CO2. This would give a risk of 1.3·10-8 fatality per annum. Such value, probably underestimated, is much lower than most other natural or anthropogenic risks. Nevertheless this risk, being unevenly distributed along the whole territory, should not be overlooked and better constrained in areas with high density of gas manifestations and high soil gas fluxes.

In the winter 2013, mercury concentrations in air from the mine-polluted area of Mt. Amiata (1738 m a.s.l.), in southern Tuscany (Central Italy), were measured by active moss biomonitoring. This area is part of the geologic anomaly of Hg in the Mediterranean basin, which contains about 65 % of the world’s cinnabar (HgS). Mt. Amiata covers some 400 km2 and is drained by several rivers. Esploitation activity at Abbadia S. Salvatore, in the SE sector of the mountain, sprang up during the 19th century as one of the largest mercury mining and smelting plants in Europe, after those of Almaden Spain. In this area, Sphagnum moss bags were exposed for about two months, from October to December 2013. At each site (10 sites), one covered and one uncovered moss bag were deployed. Concentrations of mercury in air were also investigated in the same sites with a portable spectrophotometer (Lumex RA-915M). After exposure, mosses were oven-dried, grinded and each sample was divided in two aliquots: one was analyzed for mercury by using a Hydra C cold vapor atomic absorption analyzer (INGV-Palermo), following 7473 US EPA method; the second was microwave digested in acid solution (HNO3 + H2O2). Extraction solutions were analyzed by ICP-MS for total concentrations of a large suite of trace elements, including potentially toxic elements e.g. As, Cd, Cr, Cu, Mo, Sb, Se, V. Mercury air concentrations measured with the Lumex showed extremely high values in the mine district of Abbadia, with median values ranging from 2,000 to 4,000 ng/m3 and maximum values up to 20,000 ng/m3, in contrast with the lower values (median values from 20 to 200 ng/m3) measured in the distal sites few kilometres from the mine-district area. In agreement with these results, in the vicinity of the district uncovered bags were in the range of 10,000 – 100,000 ng/g of Hg, whereas in the distal sites they were in the range of 1,000 – 10,000 ng/g. The moss-blank (unexposed moss) was ~100 ng/g. Covered moss bags were not significantly enriched in Hg with respect to the concentrations recovered from the moss-blank, suggesting that the mercury trapped in the mosses was mainly in particulate form. The particles carried from the winds were probably associated with soils re-mobilization, as also confirmed by the associated enrichments of some lithophile elements (Li and lanthanides) and anthropogenic element (As, Cr, Cd, Fe, Se, V). These preliminary results confirm the intense contamination of the study area not only for mercury but also for other potentially toxic elements.

Volcanic and geothermal areas are important emitters of natural gas compounds into the atmosphere, which can be of concern when discharging close to densely, populated sites. Mercury has a strong environmental impact, its organic and inorganic complexes being toxic. The dominant form of Hg in the atmosphere is gaseous elemental mercury (GEM), which has high volatility and residence time of 1-2 years. Volcanic degassing accounts for a significant part of the natural mercury emissions. No mercury limits or target values in ambient air are present in the EU legislations, whereas US-EPA and ATSDR impose 300 and 200 ng/m3, respectively, as a limit for chronic exposure. WHO has proposed the annual average value of 1,000 ng/m3 as a guideline for Hg0 in ambient air. The determination of Hg0 concentrations is often performed via passive/diffusive samplers, which provide time-integrated gas concentrations, but not able to assess the highly variable distributions of GEM. Different weather factors and photochemical reactions indeed affect the Hg0 dispersion. In volcanic/geothermal sites, GEM measurements can be associated with H2S, an irritating and suffocating substance and detectable at very low concentrations (7 μg/m3, ~5 ppb) due to its typical rotten eggs odor. WHO recommends a guideline value of 150 μg/m3 (~107 ppb) with a 24h averaging time. In April 2014 real-time Hg0 and H2S measurements in air were conducted at the Solfatara Crater, which is nested in the town of Pozzuoli (Southern Italy). The main aims were to (1) test this new methodological approach and (2) investigate the Hg0 the H2S concentrations and their spatial distribution. GEM and H2S continuous measurements were determined with a portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M, DL: 2ng/m3) and a pulsed fluorescence gas analyzer (Thermo 450i, DL: 1 ppb), respectively. The GEM and H2S and meteorological data were acquired along previously planned pathways at an average speed

From 25th of October to 5th of November 2014 field surveys were carried out at Nyiragongo and Nyamulagira volcanoes, DR Congo. These two volcanoes belong to the eight volcanoes in the Virunga volcanic chain. They have an altitude of about 3470 m.a.s.l. and 3060 m.a.s.l., respectively. The craters of the two volcanoes lie within a distance of less than 15 km and both have a diameter of about 1000 m and 2000 m, respectively showing a similar inner geometry containing several terraces inside. The lava lake of Nyamulagira is still under formation while Nyiragongo’s lava lake is known since more than 100 years with short interruptions after the eruptions in 1977 and 2002. However, also Nyamulagira had a long period of lava lake activity, at least from 1912 to 1938. Both volcanoes are characterized by low SiO2 content of their lava, but Nyiragongo being exceptionally low in SiO2 and with significantly higher alkali content than Nyamulagira. There is a clear distinction between both lavas; a basaltic to tephritic one in the case of Nyamulagira and an often foidite one in the case of Nyiragongo. Also their volcanic activity has differed significantly during the last decades from each other. While Nyiragongo is famous for its permanent lava lake, Nyamulagira is characterized by frequent eruptions, which sum up to more than 40 since 1865. During our field survey we investigated and compared the gas composition and fluxes of both volcanoes in autumn 2014. The ground - based remote sensing technique - Multi Axis Differential Optical Absorption spectroscopy (MAX-DOAS) using scattered sunlight, the in-situ Multi-GAS-instrument, as well as active alkaline and particle traps have been simultaneously applied at each crater of the two volcanoes during the field trip. Downwind installed DOAS instruments (appendant to NOVAC (Network of Observation of Volcanic and Atmospheric Change)) were used to determine SO2 emission fluxes. Among others, bromine monoxide/sulphur dioxide (BrO/SO2) and carbon dioxide/sulphur dioxide (CO2/SO2) ratios were calculated to differ between Nyamulagira and Nyiragongo by of about a factor 5 and 3, respectively. Fluxes of major compounds (CO2, H2O, SO2, HCl, HF, HBr) and trace elements (Cd, Cu, As, Pb, Zn, etc.) will be here presented, giving a very detailed view of similarities and differences between the plume of both volcanoes. The differences in the gas composition of these two plumes will be discussed and with a view on earlier petrological data some possible processes responsible for them will be proposed.

Real-time measurements of GEM and H2S discharged from natural and anthropogenic sources are a valuable tool to investigate the dispersion dynamics of these contaminants in air. In this study, a new approach to measure GEM and H2S concentrations in air, carried out by coupling a portable Zeeman atomic absorption spectrometer with high frequency modulation of light polarization (Lumex RA-915M) and a pulsed fluorescence gas analyzer (Thermo Scientific Model 450i), was applied to two distinct areas: (i) in the surroundings of Piancastagnaio (Siena, Central Italy), located in the eastern flanks of Mt. Amiata (a 200,000Âyears old volcano), where three geothermal plants are operating and whose exhaust gases are dispersed in the atmosphere after passing through the turbines and an abatement system to mitigate the environmental impact on air, and (ii) at Solfatara Crater (Campi Flegrei, Southern Italy), a volcanic apparatus characterized by intense hydrothermal activity. In 2014, seven GEM and H2S surveys were carried out in the two areas along pre-defined pathways performed by car at both the study sites. The lowest and highest recorded GEM and H2S concentrations at Piancastagnaio were up to 194 and 77Âng/m3, respectively, whilst at Solfatara Crater were up to 690 and 3392Âμg/m3, respectively. Although the GEM concentrations at Piancastagnaio were lower than the limit value recommended by local regulations for outdoor environment (300Âng/m3), they were almost one order of magnitude higher than the GEM background both in Tuscany (~Â3.5Âng/m3) and Mt. Amiata (3–5Âng/m3), suggesting that the main source of GEM was likely related to the geothermal plants. At Solfatara Crater, the highest GEM values were recognized in proximity of the main fumarolic gas discharges. As far as the H2S concentrations are concerned, the guideline value of 150Âμg/m3, recommended by WHO (2000), was frequently overcome in the study areas. Dot (in the surroundings of Piancastagnaio) and contour (at Solfatara Crater) maps for GEM and H2S concentrations built for each survey highlighted the important effects played by the meteorological parameters, the latter being measured by a Davis® Vantage Vue weather station. In particular, the GEM and H2S plumes were strongly affected by the wind speed and direction that were able to modify the dispersion of the two parameters in air in a matter of hours, indicating that the proposed analytical approach is able to produce a more realistic picture of the distribution of these air pollutants than that provided by using passive traps. Finally, the H2S/GEM ratio, calculated by normalizing the measured GEM and H2S concentrations to their highest values (nH2S/GEM), was used as a good proxy for the chemical-physical processes that these two gas species can suffer once emitted in the air. In particular, H2S resulted to be more affected by secondary processes than GEM, possibly related to photochemical oxidation reactions.

We have performed leaching experiments on the fine (< 2 mm) particulate sampled in seven active and quiescent volcanic systems in the Mediterranean area. We reacted the particulate both in pure water and in a synthetic gastric solution. The amount of As, Mn, Pb, Ba, U and Ni leached by pure water exceeded the MAC limits for drinking water in all the materials under investigation. We defined a tolerable ash intake index (TAI) to evaluate the impact of ash ingestion, and we find that 0.2 g and 12 g of ingested fine ash from Vesuvius and Vulcano are enough to exceed the safety limits for Pb and As. Six grams of fine ashes from Stromboli are sufficient to overstep the safety limits for As. Based on our mineralogical characterisation of the particulate, we expect that the submillimetric ash fraction, with a higher surface/volume ratio, releases a greater relative amount of trace metals, which are concentrated in the thin surface layer produced by the reaction of the pristine volcanic particles with coexisting volcanic gases. This means that our measurements represent lower bounds to the actual amount of metal released in aqueous solutions by the volcanic ashes from the locations under investigation. Our results place the first constraints on the mobilisation of toxic elements from volcanic ash, which are necessary to assess the associated potential health risk of volcanic areas. © 2017 Elsevier B.V.

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 CO2, 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. © 2017 Elsevier B.V.

Volcanic and geothermal systems emit endogenous gases by widespread degassing from soils, including CH4, a greenhouse gas 25 times as potent as CO2. Recently, it has been demonstrated that volcanic/geothermal soils act as source, but also as biological filter for methane release to the atmosphere. For long time, volcanic/geothermal soils has been considered inhospitable for methanotrophic microorganisms, but new extremophile methanotrophs belonging to Verrucomicrobia were identified in three different areas (Pozzuoli, Italy; Hell’s Gate, New Zealand; Kamchatka, Russia), explaining anomalous behaviours in methane leakages of several geothermal/volcanic sites. Our aim was to increase the knowledge of the relationship between methane emissions from volcanic/geothermal areas and biological methane oxidation, by investigating a geothermal site of Pantelleria island (Italy). Pantelleria Island hosts a high enthalpy geothermal system characterized by high temperature, high CH4 and very low H2S fluxes. Such characteristics are reflected in potentially great supply of methane for methanotrophs and scarce presence of inhibitors of their activity (H2S and NH3) in the Pantelleria soils. Potential methanotrophic activity within these soils was already evidenced by the CH4/CO2 ratio of the flux measurements which was lower than that of the respective fumarolic manifestations indicating a loss of CH4 during the gas travel towards the earth’s surface. In this study laboratory incubation experiments using soils sampled at Favara Grande, the main hydrothermal area of Pantelleria, showed very high methane consumption rates (up to 9500 ng CH4 h1 g1). Furthermore, microbiological and culture-independent molecular analyses allowed to detect the presence of methanotrophs affiliated to Gamma- and Alpha-Proteobacteria and to the newly discovered acidothermophilic methanotrophs Verrucomicrobia. Culturable methanotrophic Alpha-proteobacteria of the genus Methylocystis were isolated by enrichment cultures. The isolates showed a wide range of tolerance to pH (3.5 – 8) and temperatures (18 – 45 C), and an average methane oxidation rate of 450 ppm/h. A larger diversity of proteobacterial and verrucomicrobial methanotrophs was detected by the amplification of the methane mono-oxygenase gene pmoA. This study demonstrates the coexistence of both the methanotrophic phyla Verrucomicrobia and Proteobacteria in the same geothermal site. The presence of proteobacterial methanotrophs was quite unexpected because they are generally considered not adapted to live in such harsh environments. Their presence at Favara Grande could be explained by not so low soil pH values (> 5) of this specific geothermal site and by the high methane availability. Such species could have found their niches in the shallowest part of the soils, were the temperatures are not so high, thriving on the abundant upraising methane. Understanding the ecology of methanotrophy in geothermal sites will increase our knowledge of their role in methane emissions to the atmosphere.

Explosive eruptions and volcanic passive degassing inject large quantities of gas and particles into the atmosphere that are ultimately deposited at the Earth’s surface through wet or dry deposition processes, affecting the atmosphere, the hydrosphere and the biosphere. Mount Etna (Italy) is one of the most prodigious and persistent sources of gases and particles to the troposphere. Volcanic emissions were studied at Etna volcano by using moss-bags technique. Mosses (Sphagnum species) were exposed around the volcano at different distances from the active vents to evaluate the impact of its emissions into the atmosphere and in the local surrounding. The results confirmed the huge amount of silicates, sulfates and halides compounds emitted into the atmosphere from Mount Etna. X-ray microanalysis showed that chemical composition of the particles is mostly defined by silicate (from pure silica to metal-rich silicate composition) and sulfate/halide compounds. The contents of major and trace elements in the Sphagnum moss-bags significantly increased after their exposure to volcanic emissions, confirming mosses as efficient accumulators. Metals uptake rate rapidly decreases with the distance from the volcanic emission vents. The elements that showed the greatest accumulation after exposition were S, Na, Fe, Al, Cu, V, As, Cd, Li, Se, Sc, Th, Bi and Tl. This study confirmed the marked environmental impact of volcanic emissions in the eastern sector of Etna, leading to an intense “geochemical anomaly” of volatile major and trace elements due to the fumigation by the volcanic plume, in agreement with passive biomonitoring studies reported by previous authors. Finally, moss-bags techniques provide a cheap and efficient method to investigate quantitatively in space and time the environmental impact of volcanogenic atmospheric deposition.

Bulk deposition has been collected at six sampling sites in area of Gela plain (Italy) in the period from February 2008 to May 2009. Samples collected each two weeks were analysed for the major ion and trace elements content. Preliminary results allow identifying three different sources that control the abundance of the elements in atmospheric deposition: (1) sea spray, (2)geogenic dust, and (3) anthropogenic pollution. Due to the closeness of the coast, clear evidence of sea spray input is detectable for most of the samples. The high excess of non sea-salt sulphate(50 - 90% of the total) is prevailingly ascribable to the abundant SO2 emissions of the refinery.The pH values of the collected samples range from 4.2 to 8.6, with 80% of them above pH 6.5,indicating an extensive neutralization. This is due to NH3 coming from widespread agricultural activities in the plain of Gela, and geogenic CaCO3 either from local or from regional (desert dust) sources. Elevated levels of trace metals (Zn, V, Sb, Ni, Cr, Ni and Cu) can be observed in the samples collected close to the industrial area. All these elements can be identified as “anthropogenic” and attributed to the human activities, mainly to the industrial emissions, but a contribution could also derive from the intensive vehicular traffic.

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 2004e2012, 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.

Biomonitoring techniques have been widely used in environmental studies to monitor anthropogenic pollutant. Recently such techniques have been applied also to ascertain the impact of contaminants naturally released by volcanic activity. In the present study a biomonitoring surveys has been performed in many different active volcanic systems: Mt. Etna and Vulcano (Italy), Nisyros (Greece), Nyiragongo (DRC), Masaya (Nicaragua), Gorely (Kamchatka, Russia). We sampled leaves of different species Betulla aethnensis, Pinus nigra, Populus tremula, Senecio aethnensis and Rumex aethnensis on Etna, Cistus creticus and salvifolius on Vulcano and Nisyros, Senecio ssp. on Nyiragongo, a Fern on Masaya and Salix arctica at Gorely. All samples were analyzed by ICP-MS and ICP-OES for 49 elements after acid digestion with a microwave oven (HNO3 + H2O2). Major constituents in leaves are K, Ca, Mg, Na, Si, Al and Fe ranging from about 10 3 to 105 ppm. Manganesium, Sr, Rb, Ba, Zn, B, Cu show also relatively high concentrations (100-103 ppm) while the remaining elements (As, Bi, Cd, Ce, Co, Cr, Cs, Ga, Li, Mo, Ni, Pb, Sb, Sc, Se, Th, Tl, U, V, Y and lanthanide series) display much lower values (10-4-101 ppm). Nearly all investigated elements show their highest concentrations in the samples collected closest to the main degassing vents (open craters, fumarolic fields). Increased concentrations are also found in the samples collected in the downwind direction where volcanic emissions are prevailingly dispersed. Leaves collected along radial transects from the active vents, highlight that the levels of metals decrease from one to two orders of magnitude with increasing distance from the source. The decrease is stronger for volatile elements, which are highly enriched in volcanic emissions, (As, Bi, Cd, Cs, Pb, Sb, Tl) than for more refractory elements (Al, Ba, Sc, Si, Sr, Th, U). The different species of plants show significant differences in the bioaccumulation processes for most of the analyzed elements, in particular lanthanides, which are systematically enriched in Rumex leaves. Needles of pine (non-deciduous tree) represent a good tool for biomonitoring investigation because they are important tracers of accumulation with time. The high concentrations of many toxic elements in the leaves allow us to consider some of these plants as highly tolerant species to the volcanic emissions, and suitable for biomonitoring researches further confirming their strong potential in tracing the impact and geographic distribution of these natural contaminants.

Quantification of gaseous emissions in geological systems is an important branch because it is a major source of greenhouse gas to the atmospheric budget. Of geological environments, there are two different categories: the first category includes emissions of the predominant carbon dioxide (CO 2), while the second includes emissions of the predominant methane (CH4). The Hellenic territory has a very complex geodynamic setting deriving from a long and complicated geological history. It is strongly characterized by intense seismic activity and enhanced geothermal gradient. This activity, with the contribution of an active volcanic arc, favours the existence of many cold and thermal gas manifestations. Geogenic sources release huge amounts of gases, which, apart from having important influences on the global climate, could also have a strong impact on human health. Geochemical studies based on the isotopic composition of carbon and hydrogen, along with helium isotopic ratios have become a good indicator of the origin of the gas. The isotopic ratio 13C/12C of CO 2 expressed in δ 13C (provides important information about the amount of CO 2 released from the Earth's crust or mantle. For methane, carbon and hydrogen isotopic compositions and C1/(C2+C3) hydrocarbon ratios can characterize the origin of methane: biogenic (thermogenic or microbial) or abiogenic. Helium isotopic ratios provide additional information about crustal or mantle origin of the gas. In the present work, a large set of chemical and isotopic data is presented aiming at the identification of areas with geogenic gas emissions and their characterization in terms of different gas composition and origin. The present catalogue should be the base for the estimation total nationwide geogenic CO 2 and CH4 fluxes.

Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere. Due to their potential toxicity they may have important environmental impacts from the local to the global scale and they can severely affect the atmospheric and terrestrial environment also at timescales ranging from a few to million years. Etna volcano is known as one of the largest global contributors of magmatic gases (CO2, SO2, and halogens) and particulate matter, including some toxic trace elements. The aim of this study was to characterize the chemical composition and the mineralogical features of the volcanogenic aerosol passively emitted from Mt. Etna. Nine samples were collected by using the filtration technique at different sites on summer 2010 and 2011. Chemical and mineralogical analyses allowed to discriminate two main constituents: the first is mainly referable to the silicate component in the volcanic plume, like lithic and juvenile fragments, crystals (e.g., plagioclases, pyroxenes, oxides) and shards of volcanic glass; the second one is linked to the soluble components like sulfosalts or halide minerals (sulfates, chlorides and fluorides). These investigations are especially important in the study area because the summit of Mt. Etna is yearly visited by nearly one hundred thousand tourists that are exposed to potentially harmful compounds.

Methane is a major contributor to the greenhouse effect, its atmospheric concentration being more than doubled since the XIX century. Every year 22 Tg of methane are released to the atmosphere from several natural and anthropogenic sources. Natural sources include geothermal/volcanic areas but the estimation of the total methane emission from these areas is currently not well defined since the balance between emission through degassing and microbial oxidation within the soils is not well known. Microbial oxidation in soils contributes globally for about 3-9% to the removal of methane from the atmosphere and recent studies evidenced methanotrophic activity also in soils of volcanic/geothermal areas despite their harsh environmental conditions (high temperatures, low pH and high concentrations of H2S and NH3). Methanotrophs are a diverse group of bacteria that are able to metabolize methane as their only source of carbon and energy and are found within the Alpha and Gamma classes of Proteobacteria and within the phylum Verrucomicrobia. Our purpose was to study the interaction between methanotrophic communities and the methane emitted from the geothermally most active site of Pantelleria island (Italy), Favara Grande, whose total methane emission has been previously estimated in about 2.5 t/a. Laboratory incubation experiments with soil samples from Favara Grande showed methane consumption values of up to 9500 ng g1 dry soil per hour while soils collected outside the geothermal area consume less than 6 ng g1 h1. The maximum consumption was measured in the shallowest part of the soil profile (1-3 cm) and high values (>100 ng g1 h1) were maintained up to a depht of 15 cm. Furthermore, the highest consumption was measured at 37 C, and a still recognizable consumption (>20 ng g1 h1) at 80 C, with positive correlation with the methane concentration in the incubation atmosphere. These results can be considered a clear evidence of the presence of methanotrophs that were investigated by culturing and culture-independent techniques. The diversity of proteobacterial methanotrophs was investigated by creating a clone library of the amplified methane mono-oxygenase encoding gene, pmoA. Clone sequencing indicates the presence of Gammaproteobacteria in the soils of Favara Grande. Enrichment cultures, on a mineral medium in a CH4-enriched atmosphere, led to the isolation of different strains that were identified as Methylocistis spp., which belong to the Alphaproteobacteria. The presence of Verrucomicrobia was detected by amplification of pmoA gene using newly designed primers. Soils from Favara Grande show therefore the largest spectrum of methanotrophic microorganisms until now detected in a geothermal environment. While the presence of Verrucomicrobia in geothermal soils was predictable due to their thermophilic and acidophilic character, the presence of both Alpha and Gamma proteobacteria was unexpected. Their presence is limited to the shallowest part of the soil were temperatures are lower and is probably favored by a soil pH that is not too low (pH 5) and their contribution to biological methane oxidation at Pantelleria is significant. Understanding the ecology of methanotrophy in geothermal sites will increase our knowledge of the role of soils in methane emissions in such environments.

Methane plays an important role in the Earth’s atmospheric chemistry and radiative balance being the most important greenhouse gas after carbon dioxide. It has recently been established that geogenic gases contribute significantly to the natural CH4 flux to the atmosphere (Etiope et al., 2008). Volcanic/geothermal areas contribute to this flux, being the site of widespread diffuse degassing of endogenous gases (Chiodini et al., 2005). In such an environment soils are a source rather than a sink for atmospheric CH4 (Cardellini et al., 2003; Castaldi and Tedesco, 2005; D’Alessandro et al., 2009; 2011; 2013). Due to the fact that methane soil flux measurements are laboratory intensive, very few data have been collected until now in these areas. Preliminary studies (Etiope et al., 2007) estimated a total CH4 emission from European geothermal and volcanic systems in the range 4-16 kt a-1. This estimate was obtained indirectly from CO2 or H2O output data and from CO2/CH4 or H2O/CH4 values measured in the main gaseous manifestations. Such methods, although acceptable to obtain order-of-magnitude estimates, completely disregard possible methanotrophic activity within the soil. At the global scale, microbial oxidation in soils contributes for about 3-9% to the total removal of methane from the atmosphere. But the importance of methanotrophic organisms is even larger because they oxidise the greatest part of the methane produced in the soil and in the subsoil before its emission to the atmosphere. Environmental conditions in the soils of volcanic/geothermal areas (i.e. low oxygen content, high temperature and proton activity, etc.) have been considered inadequate for methanotrophic microrganisms. But recently, it has been demonstrated that methanotrophic consumption in soils occurs also under such harsh conditions due to the presence of acidophilic and thermophilic Verrucomicrobia. These organisms were found in Italy at the Solfatara di Pozzuoli (Pol et al., 2007), in New Zealand at Hell’s Gate (Dunfield et al., 2007) and in Kamchatka, Russia (Islam et al., 2008). Both the Italian and the Hellenic territories are geodynamically very active with many active volcanic and geothermal areas. Here we report on methane flux measurements made at Pantelleria (Italy) and at Sousaki and Nisyros (Greece). The total methane output of these three systems is about 10, 19 and 1 t a-1, respectively (D’Alessandro et al., 2009; 2011; 2013). The total emissions obtained from methane flux measurements are up to one order of magnitude lower than those obtained through indirect estimations. Clues of methanotrophic activity within the soils of these areas can be found in the CH4/CO2 ratio of the flux measurements which is always lower than that of the respective fumarolic manifestations, indicating a loss of CH4 during the travel of the gases towards earth’s surface. Furthermore laboratory methane consumption experiments made on soils collected at Pantelleria and Sousaki revealed, for most samples, CH4 consumption rates up to 9.50 μg h-1 and 0.52 μg h-1 respectively for each gram of soil (dry weight). Only few soil samples displayed no methane 2 consumption activity. Finally, microbiological and molecular investigations allowed us to identify the presence of methanotrophic bacteria belonging to the Verrucomicrobia and to the Alpha- and Gamma-Proteobacteria in the soils of the geothermal area of Favara Grande at Pantelleria. While the presence of the former was not unexpected due to the fact that they include acidophilic and thermophilic organisms that were previously found in other geothermal environments, the latter are generally considered not adapted to live in harsh geothermal environments. Their presence in the soils of Pantelleria could be explained by the fact that these soils do not have extremely low pH values (>5). Indeed thermotollerant methanotrophic Gamma-proteobacteria, have been previously found in the sediments of thermal springs in Kamchatka (Kizilova et al., 2012). Such species could find their niches in the shallowest part of the soils of Favara Grande were the temperatures are not so high and they thrive on the abundant upraising hydrothermal methane. References: Cardellini C., Chiodini G., Frondini F., Granieri D., Lewicki J., Peruzzi L., 2003. Accumulation chamber measurements of methane fluxes: application to volcanic–geothermal areas and landfills. Appl. Geochem. 18, 45–54. Castaldi S., Tedesco D., 2005. Methane production and consumption in an active volcanic environment of Southern Italy. Chemosphere 58, 131–139. Chiodini G., Granieri D., Avino R., Caliro S., Costa A., 2005. Carbon dioxide diffuse degassing and estimation of heat release from volcanic and hydrothermal systems. J. Geophys. Res. 110, B08204. D’Alessandro W., Bellomo S., Brusca L., Fiebig J., Longo M., Martelli M., Pecoraino G., Salerno F., 2009. Hydrothermal methane fluxes from the soil at Pantelleria island (Italy). J. Volcanol. Geotherm. Res. 187, 147–157. D’Alessandro W., Brusca L., Kyriakopoulos K., Martelli M., Michas G., Papadakis G., Salerno F., 2011. Diffuse hydrothermal methane output and evidence of methanotrophic activity within the soils at Sousaki (Greece). Geofluids 11, 97–107 D’Alessandro W., Gagliano A.L., Kyriakopoulos K., Parello F., 2013. Hydrothermal methane fluxes from the soil at Lakki plain (Nisyros island, Greece). Bull. Geol. Soc. Greece, vol. XLVII Proc. of the 13th International Congress, Chania, Sept. 2013 Dunfield P.F., Yuryev A., Senin P., Smirnova A.V., Stott M.B., Hou S., Ly B., Saw J.H., Zhou Z., Ren Y, Wang J., Mountain B.W., Crowe M.A., Weatherby T.M., Bodelier P.L.E., Liesack W., Feng L., Wang L., Alam M., 2007. Methane oxidation by an extremely acidophilic bacterium of the phylum Verrucomicrobia. Nature, 450, 879–882. Etiope G., Fridriksson T., Italiano F., Winiwarter W., Theloke J., 2007. Natural emissions of methane from geothermal and volcanic sources in Europe. J. Volcanol. Geotherm. Res. 165, 76–86. Etiope G., Lassey K.R., Klusman R.W., Boschi E., 2008. Reappraisal of the fossil methane budget and related emission from geologic sources. Geophys. Res. Lett. 35, L09307. Islam T., Jensen S., Reigstad L.J., Larsen Ø., Birkeland N.K., 2008. Methane oxidation at 55°C and pH 2 by a thermoacidophilic bacterium belonging to the Verrucomicrobia phylum. Proc. Natl. Acad. Sci. 105, 300–304. Kizilova A.K., Dvoryanchikova E.N., Sukhacheva M.V., Kravchenko I.K., Gal’chenko V.F., 2012. Investigation of the communities of the Hot Springs of the Uzon Caldera, Kamchatka, by Molecular Ecological Techniques. Microbiology, 81, 606-613. Pol A., Heijmans K., Harhangi H.R., Tedesco D., Jetten M.S.M., Op den Camp H.J.M., 2007. Methanotrophy below pH 1 by a new Verrucomicrobia species. Nature, 450, 874–878.

The presidency of Lyndon Baines Johnson dating from November 22, 1963 to January 20, 1969 provides authors and students of history with an understanding of how a president endeavors to secure historic legislation. It is the intention of this paper to explore beyond popular perceptions of presidential history from the exercising of power to political partisanship thus revealing the realities of Johnson's world in contrast to his recent Democratic successors; William Jefferson Clinton and Barack Hussein Obama. Often LBJ is perceived in the public imagination as the ultimate legislative president. Certainly his record from civil rights to consumer protection provides credence to this perception but this historic legacy were not the product of a single individual. Rather the successes were the product of a president, his congressional allies including Huber Horatio Humphrey and numerous activists from civil rights leaders to labor unions. Nor were these efforts without considerable obstruction and momentary defeats. In exploring three case studies; the Civil Rights Act of 1964, Medicare and the 1968 Fair Housing Act emphasis is placed less on the content contained within these pieces of legislation but the lessons including compromise, an understanding the legislative system, relying upon the "Bully Pulpit" and grassroots activism that shaped their passage.

Volcanic emissions represent one of the most relevant natural sources of trace elements to the troposphere, both during and between eruptions. Due to their potential toxicity they may have important environmental impacts from the local to the global scale. Atmospheric precipitation was collected approximately every two weeks, from April 2006 to December 2007, using a network of five rain gauges, located at various altitudes on the upper flanks around the summit craters of Etna volcano. The collected samples were analysed for major (Ca, Mg, K, Na, F, SO4, Cl, NO3) and a large suite of trace elements (Ag, Al, As, Au, B, Ba, Be, Bi, Cd, Co, Cr, Cs, Cu, Fe, Hg, La, Li, Mn, Mo, Ni, Pb, Rb, Si, Sb, Sc, Se, Sr, Th, Ti, Tl, U, V, Zn) by using different techniques (IC and ICP-MS ). The raingauges occasionally collected also fresh volcanic ashes emitted by the volcano during paroxysmal events. The ashes were retained by the filter-system used to block the coarse material. More than twenty events of ashfall were collected, but only half of these samples were suitable for a complete chemical analysis, due to the small amount of sample. In order to obtain elemental chemical composition of ashes, powdered samples were analysed by a combination of methods, including XRF, total digestion ICP-MS, INAA, and IR. The chemistry of rainwater reveals that most of the investigated elements (both major and trace elements) have higher concentrations close to the emission vent of the volcano, confirming the prevailing volcanic contribution. Rainwater composition clearly reflects the volcanic plume input. Ash-normalised rainwater composition indicates a contrasting behaviour between volatile elements, which are highly-enriched in rainwater, and refractory elements, which have low rainwater/ash concentration ratios. The degree of interaction between collected ash and rainwater was variable, depending on several factors: (i) the length of the period in which tephra was present in the sampler (the ash fall may have occurred any day from the first to the last day of the rain collecting period); (ii) the amount of rainwater fallen on the collectors after the ash-fall event, and its acidity; (iii) the granulometry of the ash samples that was widely variable (from few centimetres to micrometric particles) with increasing interaction due to the decreasing dimensions of the tephra grains; (iv) the distance of collector with respect to the craters. All these factors govern the efficiency of the dissolution processes of the volcanic ash, and the amount of elemental leaching from their surface. The results suggest that sulphate and halide salt aerosols are adsorbed onto ash particles, and their rate of dissolution in rainwater depends on solubility. Moreover, rapid chemical weathering of the silicate glass by the corrosive volcanic acid (SO2, HCl and HF) can also explain the enrichment of several refractory elements (Na, K, Ca, Mg, Si, Al, Fe, Ti, Sc).

Methane is released to the atmosphere by a wide number of natural (geological and biological) and anthropogenic sources, and is the second most important greenhouse gas after CO2. Microbial oxidation in soils by methanotrophic bacteria contributes to the removal of CH4 from the atmosphere and methanotrophic activity was also detected in volcanic/geothermal areas where degassing of endogenous gases occurs. Our aim is to describe the methanotrophs at the main exhalative area of Le Favare site at Pantelleria Island, where high CH4 consumption (up to 950 ng/g/ per h) was measured. Total soil bacterial diversity was analysed by TTGE of amplified 16S rRNA genes and the diversity of proteobacterial methanotrophs was investigated by creating a clone library of the amplified methane mono-oxygenase encoding genes, pmmoA. Enrichment cultures on a mineral medium in a CH4-enriched atmosphere led to the isolation of different strains that were identified as Methylocistis spp. Understanding the ecology of methanotrophy in geothermal sites will increase our knowledge of the role of such soils in methane emissions.

Methane plays an important role in the Earth’s atmospheric chemistry and radiative balance being the second most important greenhouse gas after carbon dioxide. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former. It has recently been established that significant amounts of geological methane, produced within the Earth’s crust, are currently released naturally into the atmosphere. Active or recent volcanic/geothermal areas represent one of these sources of geological methane. Microbial oxidation in soils contributes for about 3-9% to the total removal of CH4 from the atmosphere. Recent studies evidenced methanotrophic activity also in soils of volcanic/geothermal areas notwithstanding their harsh environmental conditions (high temperatures, low pH and high concentrations of H2S and NH3). The purpose of our study was to verify the methanotrophic potential and the bacterial diversity of the soils of the main geothermal area of Pantelleria island (Italy). Laboratory incubation experiments with soil samples collected at the main exhalative area showed methane consumption values of up to 9500 ng per g of dry soil per hour while soils collected outside the geothermal area less than 6 ng/g/h. Geothermal soils showed their maximum methane consumption in the shallowest part of the soil profile (0-3 cm) mantaining high values (>100 ng/g/h) at least up to dephts of 15 cm. Furthermore they showed the maximum consumption at about 37°C, showing a still recognizable consumption (>20 ng/g/h) at 80°C, and a positive correlation with the methane concentration in the incubation atmosphere. These results can be considered a clear evidence of the presence of methanotrophs. In order to evaluate the bacterial diversity, soil metagenomic DNA was extracted from Le Favare and analysed using a Temporal Temperature Gradient Electrophoresis (TTGE) analysis of the amplified Bacterial 16S rRNA gene. The amplification of metagenomic DNA with primers targeting Proteobacterial and Verrucomicrobial MMO (methane monooxygenase) genes is in progress. Enrichment cultures on a mineral medium in a CH4-enriched (25%) atmosphere allowed to isolate different strains that are under characterization.

Methane is the most abundant hydrocarbon in the atmosphere and a significant contributor to the radiative forcing with a global warming potential about 21 times that of CO2. Methane is released to the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter being twice as large as the former. Significant amounts of geological methane, produced within the Earth’s crust (e.g. volcanic/geothermal areas), are currently released into the atmosphere (48 Tg CH4/y). Microbial oxidation in soils by methanotrophic bacteria contributes to the removal of CH4 from the atmosphere for about 3-9%. Methanotrophs belong to the Gamma- and Alpha-proteobacteria and to the recently discovered acidophilic Verrucomicrobia. Evidence of methanotrophic activity also in soils of volcanic/geothermal areas has been recently revealed, notwithstanding their harsh environmental conditions (high temperatures, low pH, high concentrations of H2S and NH3). The purpose of our study was to verify the methanotrophic potential and the bacterial diversity of the soils of the main geothermal area of Pantelleria island (Italy). Close to the fumarolic area (Le Favare) the mean detected temperature is about 90 °C at 30 cm of depth and the mean measured pH of the soil is about 4.8. Laboratory incubation experiments with soil samples collected at the main exhalative area showed methane consumption values of up to 9500 ng/g of dry soil per hour while soils collected outside the geothermal area consumed less than 6 ng/g/h. Geothermal soils showed their maximum methane consumption in the shallowest part of the soil profile (0-3 cm). Furthermore they showed the maximum consumption at about 37°C, showing a still recognizable consumption (>20 ng/g/h) at 80°C. These results can be considered a clear evidence of the presence of methanotrophs. In order to evaluate the bacterial diversity, soil metagenomic DNA was extracted from Le Favare and analysed using a Temporal Temperature Gradient Electrophoresis (TTGE) analysis of the amplified Bacterial 16S rRNA gene. The amplification of metagenomic DNA with primers targeting Proteobacterial and Verrucomicrobial MMO (methane monooxygenase) genes is in progress. Enrichment cultures on a mineral medium in a CH4-enriched (25%) atmosphere led to the isolation of different strains that are under characterization.