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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.

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.

659 water samples from springs and wells in the Sabatini and Vicano-Cimino Volcanic Districts (central Italy) were analyzed for arsenic (As), fluoride (F-) and radon (Rn-222) concentrations. Waters mostly sourced from a shallow and cold aquifer hosted within volcanic rocks, which represents the main public drinking water supply. Cold waters from perched aquifers within sedimentary formations and thermal waters related to a deep hydrothermal reservoir were also analyzed. The highest concentrations of As and F- were measured in the thermal waters and attributed to their enhanced mobility during wate-rock interaction processes at hydrothermal temperatures. Relatively high concentrations of As and F- were also recorded in those springs and wells discharging from the volcanic aquifer, whereas waters hosted in the sedimentary units showed significantly lower contents. About 60% (As) and 25% (F-) of cold waters from the volcanic aquifer exceeded the maximum allowable concentrations for human consumption. Such anomalously high levels of geogenic pollutants were caused by mixing with fluids upwelling through faulted zones from the hydrothermal reservoir. Chemical weathering of volcanic rocks and groundwater flow path were also considered to contribute to the observed concentrations. Cold waters from the volcanic aquifer showed the highest Rn-222 concentrations, resulting from the high contents of Rn-generating radionuclides in the volcanic units. Approximately 22% of these waters exceeded the recommended value for human consumption. A specific Quality Index (QI), comprised between 1 (very low) and 4 (very high), was computed for each water on the basis of As, F- and Rn-222 concentrations and visualized through a spatial distribution map processed by means of geostatistical techniques. This map and the specific As, F- and Rn-222 maps can be regarded as useful tools for water management by local authorities to both improve intervention plans in contaminated sectors and identify new water resources suitable for human consumption.

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 (

Here we report on the first assessment of volatile fluxes from the hyperacid crater lake hosted within the summit crater of Copahue, a very active volcano on the Argentina-Chile border. Our observations were performed using a variety of in situ and remote sensing techniques during field campaigns in March 2013, when the crater hosted an active fumarole field, and in March 2014, when an acidic volcanic lake covered the fumarole field. In the latter campaign, we found that 566 to 1373 t d -1 of SO 2 were being emitted from the lake in a plume that appeared largely invisible. This, combined with our derived bulk plume composition, was converted into flux of other volcanic species (H 2 O ~ 10989 t d -1 , CO 2 ~ 638 t d -1 , HCl ~ 66 t d -1 , H 2 ~ 3.3 t d -1 , and HBr ~ 0.05 t d -1 ). These levels of degassing, comparable to those seen at many open-vent degassing arc volcanoes, were surprisingly high for a volcano hosting a crater lake. Copahue's unusual degassing regime was also confirmed by the chemical composition of the plume that, although issuing from a hot (65°C) lake, preserves a close-to-magmatic signature. EQ3/6 models of gas-water-rock interaction in the lake were able to match observed compositions and demonstrated that magmatic gases emitted to the atmosphere were virtually unaffected by scrubbing of soluble (S and Cl) species. Finally, the derived large H 2 O flux (10,988 t d -1 ) suggested a mechanism in which magmatic gas stripping drove enhanced lake water evaporation, a process likely common to many degassing volcanic lakes worldwide. Key Points First volatile flux record of crater lake gas emissions from Copahue volcano Magmatic gases breaching through the lake surface Magmatic gas stripping drive enhanced lake water evaporation Fil: Tamburello, G.. Università degli Studi di Palermo; Italia Fil: Caselli, Alberto Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentina Fil: Tassi, F.. Università degli Studi di Firenze; Italia Fil: Vaselli, O.. Università degli Studi di Firenze; Italia Fil: Calabrese, S.. Università degli Studi di Palermo; Italia Fil: Rouwet, D.. Istituto Nazionale di Geofisica e Vulcanologia; Italia Fil: Capaccioni, B.. Universidad de Bologna; Italia Fil: Di Napoli, R.. Università degli Studi di Palermo; Italia Fil: Cardellini, C.. Università di Perugia; Italia Fil: Chiodini, G.. Istituto Nazionale di Geofisica e Vulcanologia; Italia Fil: Bitetto, M.. Università degli Studi di Palermo; Italia Fil: Brusca, L.. Istituto Nazionale Geofisica e Vulcanologia; Italia Fil: Bellomo, S.. Istituto Nazionale Geofisica e Vulcanologia; Italia Fil: Aiuppa, A.. Istituto Nazionale Geofisica e Vulcanologia; Italia

International audience; Along the Jordan Valley-Dead Sea Fault area several natural waters in springs, wells, and catchments occur. The chemical-physical characters of the studied waters allowed for the first time the investigation of the Zr and Hf geochemical behavior, apart from REE, extended to a wide range of Eh, temperature, salinity, and pH conditions. The results of this study indicate that the dissolved Zr and Hf distribution in natural waters is strongly influenced by redox conditions since these in turn drive the deposition of Fe-oxyhydroxides or pyrite. In oxidizing waters saturated or oversaturated in Fe-oxyhydroxides (Group 1), superchondritic Zr/Hf values are measured. On the contrary, in waters where Eh < 0 values occur (Group 2), chondritic Zr/Hf values are found. Superchondritic Zr/Hf values are produced by the preferential Hf scavenging onto Fe-oxyhydroxides that is inhibited under reducing conditions consistent with the water oversaturation relative to pyrite. Redox conditions also influence the amplitude of Ce and Eu anomalies. Oxidized Group-1 waters show negative Ce anomalies related to the oxidative Ce scavenging as CeO2 onto Fe-oxyhydroxide. Reduced Group-2 waters show positive Eu anomaly values consistent with the larger Eu2+ concentration relative to Eu3+ in these waters suggested by model calculations. The higher stability of Eu2+ with respect to its trivalent neighbors along the REE series can explain the above mentioned positive Eu anomaly values. The middle-REE enrichment observed in shale-normalized REE patterns of studied waters can be ascribed to carbonate and/or gypsum dissolution.

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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.

The large amount of trace elements emitted from volcanoes has a strong impact on the close surrounding areas. Nyiragongo Volcano (Democratic Republic of Congo) belongs to the Virunga volcanic chain and is one of the most active volcanoes in Africa. It is characterized by the presence of an active and permanent lava lake with a persistent degassing activity. During a field trip in October-November 2014, we investigated the impact of the volcanogenic deposition in the surrounding of the crater by using different sampling techniques. Rain-gauges were used to collect atmospheric bulk deposition. Active and passive biomonitoring techniques (moss-bags and leaves of endemic plants – Senecio spp. and Amarantus viridis) were applied in order to investigate the dispersion of volcanic gas and particle emissions. We collected daily rainfall events at various sites: seven samples at the crater rim (on the western and southern side, 3470 m a.s.l.), one sample at the village Kibati (south-eastern flank, 1955 m a.s.l.) located at the up-wind base of the volcano (representing the local background), and four samples in the city of Goma (southern flank of the volcano, 1500 m a.s.l.). In order to implement our dataset, several samples of rainwater, amaranth leaves, soils and atmospheric depositions (by moss-bags and filters exposition) were sampled after the field trip by the researchers of the Goma Volcano Observatory (GVO). Since, the prevalent wind direction was blowing the plume in westerly or southwesterly direction, we exposed the raingauges in the villages of Bulengo, Rusayo and Kingi in the southwestern side respect to the volcano, and Kibumba in the southesthern as a background site, at increasing distance from the rim. In the same sites, leaves of Amarantus viridis, which is one of the principal vegetables eaten by the local population, were collected. Rainwater, moss bags and plant samples were analyzed for major and trace elements by IC, ICP-OES and ICP-MS. The large amount of emitted volcanic gases and particles includes sulfur, halogens and trace elements, that strongly affect rainwater chemistry and have a widespread impact on the surrounding vegetation of the volcano. Indeed, rainwater samples collected at the rim of the crater have low pH values (_ 3), high concentration of F- and Cl- (up to 12.0 and 12.8 mg/l, respectively) and dissolved toxic elements (such as Al, As, Cd, Cu, Fe and Pb), whereas samples from the city of Goma have pH values above 5 and the same elements show orders of magnitude lower concentrations. The biomonitoring results highlight that bioaccumulation of trace elements is extremely high in the proximity of the crater rim and decreases with the distance from the active craters. The data will be compared to earlier measurements taken in December 2011 and the impact of a slightly decreasing gas emission on the vegetation will be discussed.

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.

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.

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.