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Submarine hydrothermal systems along active volcanic ridges and arcs are highly dynamic, responding to both oceanographic (e.g., currents, tides) and deep-seated geological forcing (e.g., magma eruption, seismicity, hydrothermalism, and crustal deformation, etc.). In particular, volcanic and hydrothermal activity may also pose profoundly negative societal impacts (tsunamis, the release of climate-relevant gases and toxic metal(loid)s). These risks are particularly significant in shallow (

The chemical composition of rainwater depends on (i) the dissolution of gases and particulate matter emitted by different sources, (ii) the chemical and physical reactions occurring during local and regional scale transport, and (iii) removal processes. The source of major and trace elements dissolved in rainwater can be both natural (e.g. sea salts, volcanic emissions, geogenic dust, biogenic material) and anthropogenic (e.g. industrial plants, vehicular traffic, domestic heating, vessel traffic). A group of trace elements has been recently brought to attention, especially for their possible environmental impacts, the Technology-critical elements (TCEs): Ga, Ge, In, Te, Nb, Ta, Tl, the Platinum Group Elements and most of the rare-earth elements (REE). The current knowledge about the geochemical cycle of TCEs is still scarce and there are not many studies about the concentrations of them in the rainwater. Nevertheless, recent studies (e.g. Brugnone et al., 2020) evidenced a contribution from the volcanic activity for some of them (Te, Tl, and REE). The main aim of this research is to produce an unedited geochemical database on major and trace element concentrations and bulk depositions, in different areas of Sicily: a volcanic area (Mt Etna), two urban (Palermo and Catania), and two industrial areas (Milazzo and Priolo) and a rural monitoring site representative of the regional atmospheric background (Cesarò, Nebrodi Regional Park). The samples will be collected monthly, for almost two years, through a network of 15 bulk collectors, most of which were installed at atmospheric monitoring stations of the “Agenzia Regionale per la Protezione Ambientale - ARPA Sicilia”. Moreover, the isotopic ratios of H and O in the rainwater will be investigated, while an innovative feature of the research will be the determination of the isotopic ratios of isotopes not investigated in previous similar studies: 34S/32S, 11B/10B, 87Sr/86Sr. These isotopes have been studied in matrices such as groundwaters, river and marine waters, in which the above elements show higher concentrations than rainwater. Therefore, a new analytical methodology will be developed to measure these isotopic ratios in rainwater. The isotope fingerprint enables to distinguish the contribution of sea-salt from terrestrial and anthropogenic components, allowing to discriminate the different sources that contribute to the chemical and the isotopic composition of atmospheric bulk deposition in the Mediterranean basin.

Karst systems represent the main drinking water source for 20-25% of world’s population, although covering only 7-10% of the global land surface (Ford & Williams, 2007). Karst aquifers are highly vulnerable to external pollution, so their protection and management is of critical importance to sustain water resources. In Greece, starting from the 1970’s, water demands for agricultural, domestic and industrial use increased significantly, mainly in coastal areas (Daskalaki & Voudouris, 2008). The main Hellenic aquifers are hosted in alluvial deposits, in Neogene deposits and in carbonate rocks. The latter cover about 35% of the country and are located in Western, Central and Southern Greece (Daskalaki & Voudouris, 2008). Karst aquifers are developed in limestones and dolomites (Triassic – Cretaceous), and in marbles (Paleozoic – Mesozoic). Their hydrogeological behaviour is controlled by tectonic deformation. About 45% of them is located inland, while the rest is in coastal areas (Voudouris & Kazakis, 2018). During several field sampling campaigns from 2016 to 2020, 126 karst water samples were collected in Greece. Physicochemical parameters (temperature, pH, electric conductivity and redox potential) were measured in situ. Analyses of major ions and trace elements were performed at the laboratories of INGVPalermo. Results were compared with the limits set by the Directive 98/83/EC that fixes quality standards for drinking water. Temperatures of sampled waters ranged from 8.7 to 31 °C, pH from 6.5 to 8.4, whilst Total Dissolved Solids from 206 to 25,617 mg L-1. Most of the samples showed a typical alkaline-earth bicarbonate composition, whilst those sited along the coastline presented elevated concentrations of Na+ (up to 7,680 mg L-1), Cl- (up to 14,200 mg L-1) and SO4 2- (up to 1,940 mg L-1), sometimes exceeding the EC limits, suggesting a seawater contamination. Furthermore, karst springs contaminated by seawater, displayed high concentrations of B (up to 3,870 μg L-1) and Sr (up to 7,080 μg L-1). Nitrate concentrations were always below the EC limit (50 mg L-1), indicating a low contamination from fertilizers. Few low chloride waters showed a metal enrichment, such as Tempi springs (Thessaly) that presented enrichments in Sr (up to 242 μg L-1), Mo (up to 2.27 μg L-1), Cs (up to 1.57 μg L-1) and As (up to 17 μg L-1). Such enrichments could be attributed to the local petrological environment. Generally, karst water samples can be considered suitable for human consumption. Water quality degradation of Hellenic karst springs is mainly due to seawater intrusion or to local geogenic contamination.

Identification of transfer of mantle-derived fluids (e.g. CO2, N2, noble gases) in continental regions is critical for developing exploration strategies of natural resources (i.e., hydrocarbons, ore deposits, heat sources) and also to investigate the processes that control the deep and shallow evolution of Earth such as subduction, volcanism, natural degassing vs. active tectonic and earthquakes (e.g., O’Nions & Oxburgh, 1988; Caracausi et al., 2013; Labidi et al., 2020). Recently the outgassing of deep-mantle volatiles has been verified in different crustal segments of central-western Europe, but the geological and tectonic controls on migration of these deep fluids remain to be fully understood. To figure out the source of these volatiles can furnish new elements to the understanding of the complex regional geodynamic evolution and for the exploitation of natural resources. Furthermore, that region is also characterized by an high heat flow (< 150 mW/m2) that highlights an high geothermal energy potential that is coupled to seismicity trough the overall crust (Horwarth et al., 2015). Here, we report on the results of an extensive geochemical survey of gas manifestations in the Serbian part of the Vardar zone, a mega-suture zone between Eurasia and Africa plates. Based on their chemical compositions (C, He, Ne, Ar), the studied gases are clustered into three distinct groups (CO2-, N2- and CH4-dominated). The He isotope ratios identify a weak (

Karst aquifers are considered to be one of the most important aquifer types, as they constitute the main drinking water resource for the majority of the global population (Ford et al., 2007). They are generated from the dissolution of carbonate rocks (e.g. limestone, dolomite, marble etc.), a phenomenon commonly known as “karstification”. This process is mainly caused by the acidity of water enriched in dissolved CO2, with the concentration of the latter being dependent on both the temperature and the CO2 partial pressure of the atmosphere in contact with the water (Bakalowicz, 2005). Carbonate rocks cover about 35% of the land surface of Greece and are mainly located in the western, central and southern parts of the country (Daskalaki et al., 2008). The Hellenic karst aquifer resources are more abundant in the western part of Greece, which receives the highest amount of precipitation (1800 mm/a) (Mimikou, 2005). The karst system constitutes a strategic resource of water in the region and preserving its quantity and quality is of the utmost importance for the sustainability of the area. Seventy samples of natural water were collected from karst springs in the northern (Macedonia-Thrace) and in the central parts of Greece, during 3 campaigns from 2016 to 2018. Sampling sites were selected on the basis of the springs flow rates (> 50 L/s). Water temperature, pH, Eh and electric conductivity were measured in situ with portable instruments; major ions were determined by Ionic Chromatography (IC) on filtered (anions) or filtered and acidified (cations) samples, whereas trace elements were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) on filtered and acidified samples. All analyses were performed at the laboratories of INGV of Palermo. Chemical compositions were compared with the limits fixed by the Directive 98/83/EC, which is the most recent EU legislation that sets quality standards for drinking water. Regulations concerning the quality of drinking water as established by the Directive allow Member States to adapt the monitoring of water quality to local conditions (Karavoltsos et al., 2008). Temperatures of the sampled waters ranged from 8 to 25 °C, pH from 6.5 to 8.4, whilst Total Dissolved Solids (TDS) from 206 to 15,418 mg/L. The highest concentrations of sodium, potassium, chloride and sulfate were found in the karst springs of Central Greece (26.6-5610 mg/L; 1.56-204 mg/L; 81.06-9467 mg/L; 15-2420 mg/L, respectively), where values had sometimes exceeded the limits set by the Directive 98/83/EC, indicating a contamination due to sea water intrusion. Based on the chloride concentrations, samples were subdivided into low (Cl- < 100 mg/L) and high (Cl- > 100 mg/L) chloride karst waters. All water samples were plotted in a Langelier Ludwig diagram (Fig. 1) with the low chloride waters presenting a typical alkaline-earth bicarbonate composition. Exception is the samples of Kaliakuda, Sidirokastro and Koromilia that display enrichment in alkalis possibly due to hydrothermal activity. On the other hand, the most chloride-rich waters plot close to the sea water composition point while two samples (Rema, Mylos Kokkosi) are aligned along the seawater-groundwater mixing line (Fig. 1). Concentration ranges of major and trace elements for all waters are presented in Fig. 2, with low and high chloride samples being plotted with different symbols. High chloride group displays much higher values for Mg, SO4, Cl, Na, K, Sr, B, Li, Rb and Cs with respect to low chloride, with differences in the median values between two and three orders of magnitude. Species deriving from carbonate dissolution (Ca and HCO3) show the lowest range of concentrations both for low and high chloride waters (Fig. 2). Low chloride waters show a wide range of concentrations (three to four orders of magnitude) for trace elements such as Li, Fe, Rb, As, Mn, Cu and Cs. Trace elements were above the legislation limits (Directive 98/83/EC) mostly in the case of high chloride karst springs, showing elevated concentrations of Boron (up to 1861 μg/L), Strontium (up to 5026 μg/L) and Arsenic (up to 12.1 μg/L). In terms of Boron and Strontium, the exceeding values seem to be generally related to the intrusion of sea water. On the other hand, Arsenic, whose maximum admissible level is 10 μg/L, was above limit also in the low chloride water (17 μg/L) of Tempi, Thessalia. Few low chloride waters show a metal enrichment, such as Tempi (Sr = 242 μg/L, Mo = 2.27 μg/L, and Cs = 1.57 μg/L) and Kaliakuda (V = 3.89 μg/L, Mn = 3.65 μg/L, Fe = 71.26 μg/L, Cu = 11.55 μg/L, Zn = 22.61 μg/L, Rb = 54.7 μg/L), whilst nitrate concentrations that could indicate contamination from fertilizers or from septic tanks, are always below the maximum admissible value (50 mg/L). Most of the analyzed waters can be considered suitable for human consumption. Water quality deterioration of Hellenic karst springs is mainly due to sea water intrusion, whilst only few low chloride waters show significant enrichments in trace metals that rarely exceeds the drinking water standards. These higher contents are probably of natural origin due to local geological setting.

Earthquakes and volcanic eruptions represent a hazard. However, the impact of gases released in geodynamically active areas should not be underestimated. It is commonly known that geogenic sources release great amounts of gases, which, apart from having an important influence on the global climate, can also have a strong impact on human health causing both acute and chronic effects. In particular, CO2 and sulphur gases (mainly H2S and SO2) are the main compounds responsible for acute mortality due to their asphyxiating and/or toxic properties. One of the most known and also worst episodes occurred, took place on the 21th of August 1986 at Lake Nyos, Cameroon, when about 1700 people were killed and 850 injured by a massive CO2 release (D’Alessandro, 2006). Like other geodynamically active areas, Greece is also affected by a large number of geogenic gas manifestations (Daskalopoulou et al., 2018a). These occur either in the form of point sources (fumaroles, mofettes, bubbling gases) or of diffuse soil gas emanations (Daskalopoulou et al., 2018b). D’Alessandro and Kyriakopoulos (2013) made a preliminary estimation of the risk related to geogenic gases in Greece for the time period of 1992-2011; the whole population of the country was considered. In that period, at least two fatal episodes with a total of three victims took place, likely caused to the exposure to geogenic gases (specifically CO2). This would give a risk of 1.310-8 fatality from geogenic gas manifestations per annum. This value, although probably underestimated, is much lower than many other natural or anthropogenic risks. Since deaths due to natural gases are often wrongly attributed, it cannot be excluded that some fatal episode has not been recognized and thus that the risk is somewhat higher than assessed. Although very low, this risk should not be neglected, not only because it is possibly underestimated, but also because simple countermeasures could be adopted for risk reduction. Dangerous areas could be easily identified and delimited by geochemical prospecting and their hazards properly highlighted. Apart from the sites where fatal episodes occurred, many other hazardous sites have been recognized in Greece. Here we present data collected at Loutra Ypatis (central Greece). Study area Sperchios Basin – Evoikos Gulf Graben is a 130 km long actively spreading graben in Central Greece (1 cm/a). The high geothermal gradient of the area is evident by the presence of many thermal springs with temperatures that vary from 24 to 82 °C. In the waters of these springs, discharging along the normal faults bordering the graben, an abundant gas phase is bubbling. Loutra Ypatis is one of the emerging springs and its waters (31 °C) are exploited by a spa. The water is currently drained by a gallery and therefore the water level is about 5 m below ground at the bottom of a funnel-like hole (Fig. 1 left). For safety reasons the hole was covered by a closed building (Fig. 1 left and center). The gas, which is vigorously bubbling in the spring, is mostly (> 96%) composed of CO2 (D’Alessandro et al., 2014). The walls of the hole are covered of sulfur that derives from the partial oxidation of the H2S (2500 ppm) contained in the released gas (D’Alessandro et al., 2014). Methods In October 2015 atmospheric concentrations of CO2 were measured with a Licor LI820 NDIR spectrometer (range 0 to 20,000 ppm, accuracy of 2%), whilst in April 2016, the atmospheric concentrations of CO2 and H2S were measured with a Multi-GAS analyser manufactured by INGV-Palermo equipped with Licor LI-840 NDIR spectrometer (CO2 0-20,000 ppm) and an EZ3H electrochemical sensor by City Technology Ltd. (H2S 0–100 ppm). Simultaneous CO2, CH4 (both 0- 100%), CO, H2S (both 0-500 ppm) and O2 (0 – 25%) concentrations within the building were measured with a portable gas analyser GA2000 (Geotechnical Instruments). Results and discussion Due to the fact that a building covers the thermal spring, the intense bubbling activity of its waters creates a strong gas accumulation inside. The main component of the released gases is CO2, which has a higher density with respect to atmospheric air, thus creating the conditions for gas accumulation. About 2 m above the water level, CO2 concentrations of >95% and non-detectable O2 concentrations were measured. At higher levels above the water, CO2 concentrations were decreased but never below 50%. Such concentrations within the building are lethal for both animals and human beings. Of course, access is forbidden, but as the building is not perfectly sealed, the gases permeate to the outside through fissures and cracks. Figure 2 shows the CO2 concentrations measured in the air on October 2015 at 1.5 m height while walking around the walls of the edifice at about 2 m distance. Leaking of CO2 from the edifice is made evident by concentrations reaching values of more than 6000 ppm. The highest values were measured close to the entrance of the edifice were fissures and cracks are concentrated. Due to the tendency of CO2 to accumulate at lower levels, in this place, close to the ground, CO2 levels lethal to small animal can be reached. This was made evident by a dead bird found in that occasion (Fig. 1). In April 2016, due to the much windier conditions, CO2 concentrations at the same places reached values never exceeding 1000 ppm while H2S was always below 1 ppm. These values sharply increased getting closer to the fissures around the main entrance of the building and reached saturation of the sensors (CO2 > 20,000 ppm and H2S > 100 ppm) at a distance of few centimeters. The intense CO2 degassing observed at Loutra Ypatis may be responsible for elevated levels that can have an impact on human beings. It is worth noting that values measured in the atmosphere close to the building exceed the Occupational Recommended Exposure Limit of 5000 ppm (NIOSH, 2005). In closed spaces lethal levels can be easily reached. An older inhabitant of the close by village told us that in his childhood a playmate died by going inside the gallery that drains the thermal water out of the spa due to the high CO2 levels. Such episode underscores the need not to disregard the gas hazard created by intense natural gas manifestations like the thermal spring of Loutra Ypatis.

Areas located at plate boundaries are characterized by the presence of seismic, volcanic, and geothermal activity, as well as ore deposition. Such processes are enhanced by the circulation of hydrothermal fluids in the crust transporting volatiles from either the deep crust or the mantle to the surface. Intense geodynamic activity is also taking place in Greece giving rise to: (i) the highest seismicity in Europe, (ii) the presence of an active volcanic arc and numerous areas of anomalously high geothermal gradient, and (iii) a widespread occurrence of thermal springs. Elevated heat flow values are concentrated in Sperchios basin, an area characterised by a system of deeply rooted extensional faults and quaternary volcanic activity. This regime favoured the formation of hydrothermal systems, the surface expression of which are thermal springs with intense bubbling of CO2-rich gases. Flux measurements in the bubbling pools were made with the floating chamber method. The highest bubbling CO2 output is found in Thermopyles and Psoroneria (1 and 2 t/d, respectively). The outgoing channels of these springs have an elevated flow (>250 l/s) of gas-charged water (>15 mmol/l of CO2). Although no bubbling is noticed along the stream, the CO2 content decreases by an order of magnitude after few hundreds of metres, indicating an intense degassing from the water. Taking into account the water flow and the amount of CO2 lost to the atmosphere, the CO2 output of the outgoing channels is quantified in >10 t/d for Thermopyles and 9 t/d for Psoroneria. An estimation is also made at Ypati, Kamena Vourla, Koniavitis and Edipsos, where the mean values reach 1 t/d of CO2 for each spring. The obtained values are always higher respect to the estimated outputs from visible bubbling, suggesting that most of the degassing is “hidden”. Furthermore, the loss of CO2 from the water determines a shift in dissolved carbonate species as demonstrated by the pH increase along the channel that leads eventually to an oversaturation in carbonate minerals and therefore travertine deposition. To sum up, the total CO2 output of the study area is estimated at 30 t/d, with the major contribution deriving from the degassing along the outflow channels of the thermal springs. Such output is comparable to that of the single active volcanic systems along the South Aegean Volcanic Arc (Sousaki, Methana, Milos, Santorini, Kos and Nisyros) and highlights the importance of “hidden” degassing along CO2-oversaturated streams.

Florina Basin is located in northern Greece, close to Mount Voras where the volcanic activity of Late Messinian age began. In the area, many CO2-rich gas emissions are present as a bubbling free-phase in groundwater (both springs and wells) and soil gases. Volcanism along with the geological and geodynamic regime of the basin, created the ideal conditions for CO2 accumulation in vertically stacked reservoirs. One of these, industrially exploited by the company Air Liquide Greece, produces 30,000 t/a of CO2. Results show that CO2 concentrations in the gases of Florina can arrive up to 99.8% and are mostly above 90%. Moreover, C-isotope composition (-2.1 to + 0.3 h vs. VPDB) indicates a mixed mantle-limestone origin for CO2, while He isotope composition (R/RA from 0.21 to 1.20) shows a prevailing crustal origin with an up to 15% mantle contribution. Helium and methane, with concentrations spanning over three orders of magnitude, show a positive correlation and a consequent high variability of He/CO2 and CH4/CO2 ratios. This variability can be attributed to the interaction of the uprising gases with groundwater that chemically fractionates them due to their different solubility. Based on the CO2, CH4 and He concentrations, gas samples collected in the basin can be divided in 3 groups: a) deep reservoir gases, b) enriched in less soluble gases and c) depleted in less soluble gases. The first group consists of gas samples collected at the Air Liquide extraction wells, which tap a 300m deep reservoir. This group can be considered as the least affected by fractionation processes due to interaction with groundwater. The gases of the second group due to their interaction with shallower unsaturated aquifers, become progressively enriched in less soluble gases (He and CH4). Finally, the third group represents residual gas phases after extensive degassing of the groundwater during its hydrological pathway.

Volatiles are transported from the deep crust or mantle to the surface in geodynamically active areas where seismic, volcanic and geothermal activity is present; the circulation of hydrothermal fluids in the crust is enhanced. In such areas, faults may act as preferential pathways for advective gas-carrying fluid transport. Towards the surface, pressure decrease allows the gases to escape from the fluids into soil gas and eventually into the atmosphere (King, 1986). The migration of carbon-bearing crustal and mantle fluids contributes to Earth’s carbon cycle (Berner & Kothavala 2001). However, till now, the mechanisms, magnitudes and time variations of carbon transfer from depth to the surface remain the least understood parts of the global carbon budget. Carbon dioxide and methane are the main contributors of the total amount of C-degassing from geological (volcanic and non-volcanic) sources. From the beginning of the last century, high attention has been paid to the reservoirs of CO2 and CH4 in the atmosphere because they represent the most dangerous species in terms of global warning. The increased amount of carbon dioxide and methane in the atmosphere has important implications for the energy balance and the chemical composition of the atmosphere. Mörner and Etiope (2002) calculated that 102-103 Mt of CO2 are presumably involved in the carbon cycle every year. This estimation though, is affected by high uncertainty as a number of sources and C-degassing environments that account for this high leakage were not taken into consideration. Greece belongs to the most geodynamically active regions of the world and as such, it has to be considered an area of intense geogenic degassing. Regarding carbon, the territory is characterized by the high hydrothermal and volcanic activity of the South Aegean Active Volcanic Arc (SAAVA), and by widespread geological seeps of buried carbon dioxide and methane. In the present work, we present more than 700 literature data of free gases spread along the whole Hellenic territory to get insight on geographic distribution and composition of the released fluids. Moreover, we review all the published studies on CO2 and/or CH4 output of high degassing areas of Greece that are mainly concentrated along the SAAVA in a first attempt to estimate the total geologic output of the nation. Helium isotope data propose that the highest mantle contribution (50 to 90%) is found along the SAAVA, whereas the lowest in continental Greece (0-20%), with the atmospheric contribution being mostly negligible. Based on the geographical distribution of the gases, it is evident that the R/RA ratios and CO2 concentrations increase in areas characterized by: i) thin crust; ii) elevated heat flow values; iii) recent (Pleistocene-Quaternary) volcanic activity; and iv) deep routed extensional or transtensional regional faults. The highest values are therefore found along the SAAVA and the lowest in the western part of Greece where CH4 emission is prevailing. Furthermore, it was noticed that the majority of the samples present a prevailing limestone C component, whilst only few samples have a prevailing mantle C component (Sano and Marty, 1995). It seems barely possible though to distinguish CO2 deriving from crustal and slabrelated limestones. Additionally, due to the complex geodynamic history, the mantle C isotope composition could be affected by subduction-related metasomatism and, similarly to the nearby Italian area (Martelli et al., 2008), the C isotope composition could be more positive. In this case, the mantle contribution is probably underestimated. In terms of geogenic carbon degassing, the best studied and most exhaling area is the SAAVA, which releases 104,090 t/a of CO2 and 20.26 t/a of CH4. Continental Greece on the contrary, is much less studied but may release CO2 in the same order of magnitude in its eastern-central and northern part. The western and south-western parts of Greece are conversely the main area of methane and higher hydrocarbon degassing. Methane output of Greece is much less constrained but the presence on its territory of one of the biggest thermogenic gas seepages of Europe releasing about 200 t/a of CH4 to the atmosphere underscores its potentially high contribution. Approximately 114,310 t/a of CO2 and 221 t/a of CH4 are released from the whole Hellenic territory (Daskalopoulou et al., submitted). This estimation though, should be considered minimum as there are processes and sources that have not been taken into consideration yet. More specifically, in the submarine manifestations found at greater depths, gases cannot reach the sea surface due to the dissolution process that takes place along the water column; this is especially true for CO2 that is more soluble in water respect to other gases (eg. Milos - Dando et al., 1995; Kolumbo - Rizzo et al., 2016 etc). Moreover, the geological and geodynamic regime can contribute in the formation of CO2 reservoirs. This is the case of Florina Basin (Pearce et al., 2004) where more than one CO2 reservoirs were created, with one of them being exploited by the company Air Liquide Greece. It is worth noting that this reservoir, found at a depth of approximately 300 m, produces 30,000 t/a of CO2 (Pearce et al., 2004). Moreover, in the same area, water is also used for water supply and irrigation purposes. This water though contains a great amount of dissolved CO2 great part of which is released to the atmosphere when the water is pumped to the surface. Another source that should be underscored is the quantification of geogenic CO2 dissolved in big karstic aquifers. Chiodini et al. (1999, 2000) demonstrated that the relatively high solubility of CO2 in water plays an important role in the quantification of carbon. This approach was proved for central Italy and it might be the case for continental Greece due to the similar geodynamic history. Finally, in ophiolitic sequences where serpentinization takes place, if and when the conditions are adequate (i.e. presence of effective catalysts – Etiope and Ionescu, 2015) an abiogenic origin for CH4 seems to be favored even at low temperatures. Ophiolitic sequences crop out widely in Greece along two N-S trending belts, whilst more hyperalkaline springs or dry seeps may be present. However, their flux in generally is very low and therefore their contribution to the total natural CH4 output has probably to be considered negligible.

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.

Greece belongs to the most geodynamically active regions of the world and as such, it has to be considered an area of intense geogenic degassing. In terms of carbon, the territory is characterized by the high hydrothermal and volcanic activity of the South Aegean Active Volcanic Arc (SAAVA), and by widespread geological seeps of buried carbon dioxide and methane. In the present work, we investigate the island of Gyali located in the volcanic system Kos-Gyali-Nisyros. Nine gas samples have been collected on the island of Gyali in areas found both on land, in a small lake (∼2000 m2) along its beach, and in the sea close to the shore at shallow depths (

T he Duvalo locality is located in the SW of the Republic of North Macedonia, in the Ohrid region, near the village of Kosel. It is an area of strong soil degassing, called “volcano” by the local people despite volcanic activity has never been documented in the recent geologic history of the area [1]. A large area (thousands of sqm) shows signs of strong alteration and is devoid of vegetation. Until the 19thcentury sulphur was mined from this area [1]. In August 2019, a campaign of soil CO2 flux measurements and soil gas sampling was made. Duvalo is sometimes referred to as an active geothermal feature but no signs of enhanced geothermal gradient were found and the soil temperatures at 50 cm depth in this campaign were always within the range of local mean air temperatures. Soil CO2 flux values ranged from 1.3 to 59,000 g/m2/d and can be modelled with the overlapping of 3 or 4 flux populations. A possible biological background is estimated in 6.8±1.8 g/m2/d while the other populations are characterized by an anomalous average flux ranging from 180 to 33,000 g/m2/d. The CO2 total emission, estimated both with a statistical and geostatistical approach, provided similar values in the order of 50 t/d. This has to be considered as a minimum value because only areas with evident signs of alteration have been investigated. Nevertheless, the estimated output is quite high for an area unrelated with recent volcanism or geothermal activity. The chemical composition of soil gases shows: CO2 (96.6%), N2 (1.8%), H2S (0.6%) and CH4 (0.3%) as the main gases. The present composition is almost indistinguishable from previous analyses made in 1957 and 1977 [1] pointing to a stability of the system in last decades. The isotope compositions indicate for CO2 (δ13C -0.2 ‰) a pure carbonate rock origin, for CH4 (δ13C -34.4 ‰ and δ2H -166 ‰) a thermogenic origin and for He (R/RA 0.10) a pure crustal origin. The H2S released at Duvalo may be produced by either microbial or thermochemical sulphate reduction favoured by hydrocarbons whose presence can be inferred by the uprise of thermogenic methane. Partial oxidation of H2S during its upflow, producing sulphuric acid, may be responsible of the production of abundant CO2 through dissolution of carbonate rocks. Similar processes have been evidenced also in other parts of North Macedonia [2]. These gases rise up through the N–S trending normal faults bordering the seismically active Ohrid basin graben [3] being released to the atmosphere through the soils of Duvalo “volcano”.

A multidisciplinary field campaign was carried out at Nisyros Island (Greece). Hydrothermal gases were sampled and analysed, and CH4 and CO2 fluxes from the soils were measured with the accumulation chamber method. The sampling area (Lakki plain) covers an area of about 0.08 km2, and includes the main fumarolic areas of Kaminakia, Stefanos, Ramos, Lofos and Phlegeton. Flux values measured at 130 sites range from −3.4 to 1420 mg m−2 d−1 for CH4 and from 0.1 to 383 g m−2 d−1 for CO2. The fumarolic areas show very different CH4 degassing patterns, Kaminakia showing the highest CH4 output values (about 0.8 t a−1 from an area of about 30,000 m2) and Phlegeton the lowest (about 0.01 t a−1 from an area of about 2500 m2). The total output from the entire geothermal system of Nisyros should not exceed 2 t a−1. Previous indirect estimates of the CH4 output at Nisyros, based on soil CO2 output and CH4/CO2 ratios in fumarolic gases, were more than one order of magnitude higher. The present work further underscores the utmost importance of direct CH4 flux data because indirect methods totally disregard methanotrophic activity within the soil. Ten soil samples were collected for CH4 consumption experiments and for metagenomic analysis. Seven of the soil samples showed small but significant CH4 consumption (up to 39.7 ng g−1 h−1) and were positive for the methanotrophs-specific gene (pmoA) confirming microbial CH4 oxidation in the soil, notwithstanding the harsh environmental conditions (high temperature and H2S concentrations and low pH). © 2020 Elsevier B.V.

Rapid fluctuation of environmental conditions can impose severe stress upon living organisms. Surviving such episodes of stress requires a rapid acclimation response, e.g., by transcriptional and post-transcriptional mechanisms. Persistent change of the environmental context, however, requires longer-term adaptation at the genetic level. Fast-growing unicellular aquatic eukaryotes enable analysis of adaptive responses at the genetic level in a laboratory setting. In this study, we applied continuous cold stress (28°C) to the thermoacidophile red alga G. sulphuraria, which is 14°C below its optimal growth temperature of 42°C. Cold stress was applied for more than 100 generations to identify components that are critical for conferring thermal adaptation. After cold exposure for more than 100 generations, the cold-adapted samples grew ∼30% faster than the starting population. Whole-genome sequencing revealed 757 variants located on 429 genes (6.1% of the transcriptome) encoding molecular functions involved in cell cycle regulation, gene regulation, signaling, morphogenesis, microtubule nucleation, and transmembrane transport. CpG islands located in the intergenic region accumulated a significant number of variants, which is likely a sign of epigenetic remodeling. We present 20 candidate genes and three putative cis-regulatory elements with various functions most affected by temperature. Our work shows that natural selection toward temperature tolerance is a complex systems biology problem that involves gradual reprogramming of an intricate gene network and deeply nested regulators.

Rapid fluctuation of environmental conditions can impose severe stress upon living organisms. Surviving such episodes of stress requires a rapid acclimation response, e.g., by transcriptional and post-transcriptional mechanisms. Persistent change of the environmental context, however, requires longer-term adaptation at the genetic level. Fast-growing unicellular aquatic eukaryotes enable analysis of adaptive responses at the genetic level in a laboratory setting. In this study, we applied continuous cold stress (28°C) to the thermoacidophile red algaG. sulphuraria,which is 14°C below its optimal growth temperature of 42°C. Cold stress was applied for more than 100 generations to identify components that are critical for conferring thermal adaptation. After cold exposure for more than 100 generations, the cold-adapted samples grew ~30% faster than the starting population. Whole-genome sequencing revealed 757 variants located on 429 genes (6.1% of the transcriptome) encoding molecular functions involved in cell cycle regulation, gene regulation, signaling, morphogenesis, microtubule nucleation, and transmembrane transport. CpG islands located in the intergenic region accumulated a significant number of variants, which is likely a sign of epigenetic remodeling. We present 20 candidate genes and three putative cis-regulatory elements with various functions most affected by temperature. Our work shows that natural selection towards temperature tolerance is a complex systems biology problem that involves gradual reprogramming of an intricate gene network and deeply nested regulators.

Samples of efflorescences and encrustations of hydrothermal origin have been collected at three fumarolic areas in Greece. The three sites are Sousaki, Thiafi (Methana) and Kokkino Nero (Kos) and all belong to the South Aegean Active Volcanic Arc. Samples were analysed for their mineralogical (XRD and SEM-EDS) and chemical composition. Solutions obtained from both mineralization with HNO3 and leaching with distilled water, were analysed for major (ICP-OES), minor and trace metals (ICP-MS) and for sulfate contents (IC). Results show that their composition is mainly controlled by the petrological composition of the substrate (ultramafic rocks at Sousaki, felsic volcanic rocks at Methana and low-grade metamorphic rocks at Kos). The microenvironmental conditions (humidity, oxidizing or anoxic, exposed or sheltered from meteoric agents) as well as the rainfall regime of the area play also an important role. The presence of highly soluble sulfate minerals with elevated contents of many metals further underscores the significant influence of hydrothermal activity on elements’ mobility. The sometimes very high concentrations in toxic elements like Al, As, Co, Cr, Ni evidence also a potential environmental impact.

In the period from 2004 to 2017, more than 350 samples of free and dissolved gases were collected along the whole Hellenic area. Some literature data have also been taken into consideration (Rizzo et al., 2016). Samples have been analysed for their chemical and isotope composition. The concentrations range from 0.10 to 3370 μmol/mol for He, 600 to 995,000 μmol/mol for N2, 0.60 to 915,000 μmol/mol for CH4 and 17 to 1,002,000 μmol/mol for CO2, whereas the isotope values range from 0.01 to 7.10 for R/RA and -29.91 to +6.00 for δ13C-CO2. Considering the R/RA and 4He/20Ne ratios the atmospheric, mantle and crustal contributions for He have been calculated (Sano and Wakita, 1985). The highest mantle contribution (50 to 90%) is found in the South Aegean Active Volcanic Arc (SAAVA), whereas the lowest in continental Greece (0-20%). Atmospheric contribution is mostly negligible. Taking into consideration the geographical distribution of the gases, it is evident that the R/RA increases in areas characterized by: i) thin crust; ii) elevated heat flow values; iii) recent (Pleistocene-Quaternary) volcanic activity; and iv) deep routed extensional or transtensional regional faults. The highest values are therefore found along the SAAVA and the lowest in the western part of Greece. Furthermore, based on the CO2/3He and δ13C-CO2 values (Sano and Marty, 1995), the contribution of Sediment, Mantle and Limestone end-members for CO2 was determined. The majority of the collected samples present a prevailing limestone C component and only few samples have a prevailing mantle C component. However, with the present data, it is not possible to distinguish CO2 deriving from crustal and slab-related limestones. Additionally, due to the complex geodynamic history, the mantle C isotopic composition could be affected by subduction-related metasomatism and, similarly to the nearby Italian area (Martelli et al., 2008), the C isotope composition could be more positive. In this case, the mantle contribution is probably underestimated.

The Sperchios Basin is an actively spreading rift area with deeply rooted extensional faults and also a site of quaternary volcanic activity. Such geologic conditions favoured the formation of many hydrothermal systems, whose surface expressions are among the biggest thermal springs of the whole Greece. Degassing of deeply derived geogenic CO2 is highlighted by strong bubbling within the main pools of the springs. Flux measurements were made in the Thermopyles spring with the floating chamber method and results showed that bubbling gases in the spring release about 1 ton/day of CO2. The outgoing stream has a flow of more than 250 l/s of water rich in CO2 (about 16 mmol/l). Although no bubbling is visible along the stream, after 300 m, the CO2 content decreases to 2 mmol/l, indicating an intense CO2 degassing. This was quantified in more than 10 tons/day, suggesting that most of the degassing is not visible. Output estimations at the close by thermal springs of Psoroneria and Ypatis have not been made yet, but considering that the bubbling in their pools and the water outflow rates are similar, the CO2 emitted will be of the same order of magnitude. Further contributions from the Sperchios area may come from the Kamena Vourla springs and from diffuse soil degassing. To sum up, the best estimate of the total CO2 output of the studied area is in the order of many tens of tons/day. Such output is comparable to that of the single active volcanic systems along the South Aegean Volcanic Arc (Sousaki, Methana, Milos, Santorini, Kos and Nisyros) and it highlights the importance of hidden degassing along CO2-oversaturated streams.

Several gas samples have been collected from natural gas manifestations in the island of Milos. Most of them are located underwater along its coasts, whereas three anomalous degassing fumarolic areas (Kalamos, Paleochori and Adamas) were identified on land. Almost all the gases have CO2 as the prevailing gas species, with concentrations ranging from 88 to 99% for the samples taken underwater, while the on-land manifestations present a wider range (15-98%), being sometimes heavily contaminated by air. Methane reaches up to 1.0%, H2 up to 3.2% and H2S up to 3.5% indicating a hydrothermal origin of the gases. The isotope composition of He shows values ranging from 2.55 to 3.39 R/RA, highlighting a significant mantle contribution with the highest values measured at Adamas. C-isotope composition of CO2 is in the range from -1.9 to +1.3‰ vs. V-PDB, with most of the values found around -0.5‰ indicating a prevailing limestones origin. Isotope composition of CH4, ranging from -18.4 to-5.0‰ vs. V-PDB for C and from -295 to +7‰ vs. V-SMOW for H, points to a geothermal origin with sometimes evident secondary oxidation processes. CO2-flux measurements showed values up to 1100, 1500 and 8000 g/m2/day in the areas of Kalamos, Paleochori and Adamas respectively and up to about 23,000 g/m2/day in the marine area of Kanava. The south-western part of the island was covered with a lower density prospection, revealing only few anomalous CO2 flux values (up to 650 g/m2/day). Preliminary CO2 output estimations gave values of 1.1, 0.6 and 5.5 tons/day for the three fumarolic areas and of 1.1 tons/day for Kanava. The total output of the island (about 10 tons/day) is comparable to the other volcanic/geothermal systems of the south Aegean active volcanic arc (Nisyros, Kos, Nea Kameni, Methana and Sousaki).

Fil: Chiodini, Giovanni. Istituto Nazionale Di Geofisica E Vulcanologia. Italia. Fil: Liccioli, Caterina. Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia; Argentina. Río Negro, Argentina Fil: Vaselli, Orlando. Universita Degli Studi Di Firenze; Italia Fil: Calabrese, Sergio. Università di Palermo; Italia Fil: Tassi, Franco. Universita Degli Studi Di Firenze; Italia Fil: Caliro, Stefano. Istituto Nazionale Di Geofisica E Vulcanologia; Italia Fil: Caselli, Alberto Tomás Universidad Nacional de Rio Negro. Instituto de Investigaciones en Paleobiologia y Geologia; Argentina. Río Negro, Argentina Fil: Agusto, Mariano R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: D'alessandro, Walter. Istituto Nazionale Di Geofisica E Vulcanologia; Italia Fil: Liccioli, Caterina. Consejo Nacional de Investigaciones Científicas y Técnicas. Río Negro, Argentina. Fil: Caselli, Alberto Tomás Consejo Nacional de Investigaciones Científicas y Técnicas. Río Negro, Argentina. A geochemical survey of the main thermal waters discharging in the southwestern part of the Domuyo volcanic complex (Argentina), where the latest volcanic activity dates to 0.11 Ma, has highlighted the extraordinarily high heat loss from this remote site in Patagonia. The thermal water discharges are mostly Na-Cl in composition and have TDS values up to 3.78 g L− 1 (El Humazo). A simple hydrogeochemical approach shows that 1,100 to 1,300 kg s− 1 of boiling waters, which have been affected by shallow steam separation, flow into the main drainage of the area (Rio Varvarco). A dramatic increase of the most conservative species such as Na, Cl and Li from the Rio Varvarco from upstream to downstream was observed and related solely to the contribution of hydrothermal fluids. The equilibrium temperatures of the discharging thermal fluids, calculated on the basis of the Na-K-Mg geothermometer, are between 190 °C and 230 °C. If we refer to a liquid originally at 220 °C (enthalpy = 944 J g− 1), the thermal energy release can be estimated as high as 1.1 ± 0.2 GW, a value that is much higher than the natural release of heat in other important geothermal fields worldwide, e.g., Mutnovsky (Russia), Wairakei (New Zealand) and Lassen Peak (USA). This value is the second highest measured advective heat flux from any hydrothermal system on Earth after Yellowstone. A geochemical survey of the main thermal waters discharging in the southwestern part of the Domuyo volcanic complex (Argentina), where the latest volcanic activity dates to 0.11 Ma, has highlighted the extraordinarily high heat loss from this remote site in Patagonia. The thermal water discharges are mostly Na-Cl in composition and have TDS values up to 3.78 g L− 1 (El Humazo). A simple hydrogeochemical approach shows that 1,100 to 1,300 kg s− 1 of boiling waters, which have been affected by shallow steam separation, flow into the main drainage of the area (Rio Varvarco). A dramatic increase of the most conservative species such as Na, Cl and Li from the Rio Varvarco from upstream to downstream was observed and related solely to the contribution of hydrothermal fluids. The equilibrium temperatures of the discharging thermal fluids, calculated on the basis of the Na-K-Mg geothermometer, are between 190 °C and 230 °C. If we refer to a liquid originally at 220 °C (enthalpy = 944 J g− 1), the thermal energy release can be estimated as high as 1.1 ± 0.2 GW, a value that is much higher than the natural release of heat in other important geothermal fields worldwide, e.g., Mutnovsky (Russia), Wairakei (New Zealand) and Lassen Peak (USA). This value is the second highest measured advective heat flux from any hydrothermal system on Earth after Yellowstone.

The role and extent of horizontal gene transfer (HGT) in eukaryotes are hotly disputed topics that impact our understanding regarding the origin of metabolic processes and the role of organelles in cellular evolution. We addressed this issue by analyzing 10 novel Cyanidiales genomes and determined that 1% of their gene inventory is HGT-derived. Numerous HGT candidates originated from polyextremophilic prokaryotes that live in similar habitats as the Cyanidiales and encodes functions related to polyextremophily. HGT candidates differ from native genes in GC-content, number of splice sites, and gene expression. HGT candidates are more prone to loss, which may explain the nonexistence of a eukaryotic pan-genome. Therefore, absence of a pan-genome and cumulative effects fail to provide substantive arguments against our hypothesis of recurring HGT followed by differential loss in eukaryotes. The maintenance of 1% HGTs, even under selection for genome reduction underlines the importance of non-endosymbiosis related foreign gene acquisition.

Greece belongs to the most geodynamically active regions of the world and as such it has to be considered an area of intense geogenic degassing. Here we review all the papers already published in the scientific literature on both the geochemistry of gas manifestations and the CO2 and CH4 release, in an attempt to obtain the first nationwide inventory of the natural output of these carbon gases in Greece. The best studied and most exhaling area is the South Aegean Active Volcanic Arc (SAAVA), which releases more than 1.3 × 105 tons of CO2 per year. Continental Greece, on the contrary, is much less studied but may release CO2 in the same order of magnitude in its eastern-central and northern parts. The western and south-western parts of Greece are conversely the main areas in which methane and higher hydrocarbons degas. Methane output of Greece is much less constrained, but the presence of one of the biggest thermogenic gas seepages of Europe, which releases about 200 tons of CH4 per year to the atmosphere, underscores its potentially high contribution. © 2019 Elsevier Ltd

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 (

Este trabalho objetiva verificar os potenciais das plantas Trichilia pallida e Sesamum indicum na prospecção de acaricidas botânicos, para serem utilizados como nova alternativa para controle do ixodídeo Rhipicephalus sanguineus. O extrato hexânico (e.h.) de folhas de T. pallida e o óleo essencial de sementes de S. indicum foram obtidos em laboratório, a partir de amostras coletadas, respectivamente, em uma área de Mata Atlântica e em fazendas de cultivo no Brasil. Larvas de R. sanguineus foram obtidas a partir de fêmeas ingurgitadas, coletadas em ambientes urbanos naturalmente infestados. Os bioensaios foram realizados em quadruplicata, a 27 ± 1oC, RH ? 80% e fotoperíodo de 12 horas. Cerca de 50 larvas, de 14 a 21 dias de idade, foram acondicionadas em envelopes de papel-filtro, impregnados com diferentes concentrações das substâncias vegetais, obtidas a partir da diluição de soluções-padrão. Em cada bioensaio, foram utilizados quatro envelopes impregnados com cada concentração testada. O grupo controle usou a mesma quantidade de larvas, submetidas a: 1. Envelopes sem nenhum tratamento; 2. Envelopes tratados com água destilada e, 3. Envelopes com solventes utilizados na preparação de soluções vegetais. Pela ação do e.h. de folhas de T. pallida e do óleo de S. indicum, após 24 horas de exposição, obtiveram-se, respectivamente, CL50 de 4.660 ppm e 107.729 ppm e CL99 de 14.217 ppm e 279.912 ppm. Após 48h, obtiveram-se, respectivamente, CL50 de 1.555 ppm e 78.880 ppm e CL99 de 3.431 ppm e 221.255 ppm. Mortalidade larval significativa não foi observada no grupo controle (P < 0,05). This paper aims at verifying the potentials of Trichilia pallida and Sesamum indicum in the prospection of botanical acaricide, to be used as a new alternative to R. sanguineus control. Hexanic extract (h.e.) of T. pallida leaves and essential oil from seeds of S. indicum were obtained in laboratory, from samples collected, respectively, in an area of Atlantic forest and in agricultural farms, in Brazil. R. sanguineus larvae were obtained from engorged females collected in naturally infested urban environs. Bioassays were carried out in quadruplicate, at 27 ± 1oC, RH ? 80% and photoperiod of 12 hours. About 50 larvae, from 14 to 21 days of age, were conditioned in filter paper envelopes, impregnated with different concentrations of vegetable substances, obtained from dilution of stock solutions. In each bioassay, four envelopes impregnated with each tested concentration were used. The control group used the same amount of larvae, submitted to: 1. envelopes with no treatment; 2. envelopes with distilled water and, 3. envelopes having solvents used in the preparation of vegetable solutions. For the action of h.e. leaves of T. pallida and S. indicum oil, after 24h of exposure, it was obtained, respectively, LC50 of 4,660 ppm and 107,729 ppm and LC99 of 14,217 ppm and 279,912 ppm. After 48h, it was obtained, respectively, LC50 of 1,555 ppm and 78,880 ppm and LC99 of 3,431 ppm and 221,255 ppm. There was no significant mortality rate within the control group (P < 0.05). Made available in DSpace on 2019-11-21T18:08:30Z (GMT). No. of bitstreams: 1 26907.pdf: 229077 bytes, checksum: 7a95db95b8292ea0f42eea7f00e9bd3b (MD5) Previous issue date: 2019

Forty-five gas samples have been collected from natural gas manifestations at the island of Kos - the majority of which are found underwater along the southern coast of the island. On land, two anomalous degassing areas have been recognized. These areas are mainly characterized by the lack of vegetation and after long dry periods by the presence of sulfate salt efflorescence. Carbon dioxide is the prevailing gas species (ranging from 88 to 99%), while minor amounts of N2 (up to 7.5%) and CH4 (up to 2.1%) are also present. Significant contents of H2 (up to 0.2%) and H2S (up to 0.3%) are found in the on-land manifestations. Only one of the underwater manifestations is generally rich in N2 (up to 98.9%) with CH4 concentrations of up to 11.7% and occasionally extremely low CO2 amounts (down to 0.09%). Isotope composition of He ranges from 0.85 to 6.71 R/RA, indicating a sometimes-strong mantle contribution; the highest values measured are found in the two highly degassing areas of Paradise beach and Volcania. C-isotope composition of CO2 ranges from -20.1 to 0.64‰ vs. V-PDB, with the majority of the values being concentrated at around -1‰ and therefore proposing a mixed mantle - limestone origin. Isotope composition of CH4 ranges from -21.5 to +2.8‰ vs. V-PDB for C and from -143 to +36‰ vs. V-SMOW for H, pointing to a geothermal origin with sometimes-evident secondary oxidation processes. The dataset presented in this work consists of sites that were repeatedly sampled in the last few years, with some of which being also sampled just before and immediately after the magnitude 6.6 earthquake that occurred on the 20th of July 2017 about 15 km ENE of the island of Kos. Changes in the degassing areas along with significant variations in the geochemical parameters of the released gases were observed both before and after the seismic event; however, no coherent model explaining those changes was obtained. CO2 flux measurements showed values of up to about 104 g×m-2×d-1 in both the areas of Volcania and Kokkino Nero, 5×104 g×m-2×d-1 at Paradise beach, and 8×105 g×m-2×d-1 at Therma spring. CO2 output estimations gave values of 24.6, 16.8, 12.7, and 20.6 t×d-1, respectively, for the above four areas. The total output of the island is 74.7 t×d-1 and is comparable to those of the other active volcanic/geothermal systems of Greece (Nisyros, Nea Kameni, Milos, Methana, and Sousaki). © 2019 Kyriaki Daskalopoulou et al.

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.

The Arabidopsis genome annotation include 11 glyoxalase I (GLXI) genes, all encoding for protein members of the vicinal oxygen chelate (VOC) superfamily. The biochemical properties and physiological importance of three Arabidopsis GLXI proteins in the detoxification of reactive carbonyl species has been recently described. Analyses of phylogenetic relationships and conserved GLXI binding sites indicate that the other eight GLXI genes (GLXI-like) do not encode for proteins with GLXI activity. In this perspective article we analyse the structural features of GLXI and GLXI-like proteins, and explore splice forms and transcript abundance under abiotic stress conditions. Finally, we discuss future directions of research on this topic with respect to the substrate identification of GLXI and GLXI-like proteins and the need of reliable quantitative measurements of reactive carbonyl species in plant tissues.