There is an urgent need to better constrain the global rates of mercury degassing from natural so... more There is an urgent need to better constrain the global rates of mercury degassing from natural sources, including active volcanoes. Hitherto, estimates of volcanic fluxes have been limited by the poorly determined speciation of Hg in volcanic emissions. Here, we present a systematic characterisation of mercury partitioning between gaseous (Hg (g)) and particulate (Hg (p)) forms in the volcanic plume of Mount Etna, the largest open-vent passively degassing volcano on Earth. We demonstrate that mercury transport is predominantly in the gas phase, with a mean Hg (p) /Hg (g) ratio of $0.01 by mass. We also present the first simultaneous measurement of divalent gaseous mercury (Hg II ðgÞ) and total gaseous mercury (Hg (g)) in a volcanic plume, which suggests that Hg 0 ðgÞ is the prevalent form of mercury in this context. These data are supported by the results of model simulations, carried out with HSC thermodynamic software. Based on a mean ''bulk plume'' Hg/SO 2 mass ra...
There is some debate at present regarding the quantity of mercury naturally released by volcanoes... more There is some debate at present regarding the quantity of mercury naturally released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget a number of field campaigns were carried out to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been made of emissions of Masaya (Nicaragua), Etna and Vulcano (Italy), Tatun (Taiwan), Taal and Makiling (Philippines) and Kilauea (Hawaii, USA). Emissions from open vents, fumaroles, hot springs, bubbling mud pools and altered ground were investigated at these sites and concentrations of mercury elevated above background levels were observed on most occasions. A Lumex 915+ portable mercury vapour spectrometer was employed to record real-time gaseous elemental mercury (GEM) concentrations alongside a Multi-GAS sensor box developed to monitor SO2, H2S, CO2, humidity, temperature and pressure. These measurements were carried out...
Since the 19 March 2008 explosion within Halema`uma`u that formed the new vent at Kilauea's s... more Since the 19 March 2008 explosion within Halema`uma`u that formed the new vent at Kilauea's summit, degassing rates have been greatly elevated above the levels typical of previous years. The location and subsequent dispersion of this new degassing presents its own specific problems compared to that in the east rift zone. For example, throughout 2008 the Halema'uma'u plume was generally blown through the Kau desert, directly affecting downwind communities. In this study we present measurements made in July 2008. We characterize the gas chemistry in terms of SO2 and halogens (HF, HCl, HBr and HI) in the new plume from Halema'uma'u in order to compare them with other plumes worldwide, including those from subduction zone settings and other emissions from Kilauea itself. Further to this we characterize the plume's chemistry in terms of emissions of environmentally important metallic species both in the size-segregated aerosol (important for determining atmospheri...
Mercury is a toxic metal which has a long lifetime in the atmosphere, (~ 1 year). This long lifet... more Mercury is a toxic metal which has a long lifetime in the atmosphere, (~ 1 year). This long lifetime enables it to be carried vast distances and the metal is found in elevated concentrations in remote regions of the world. There is some debate at present regarding the quantity of mercury released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget we have carried out a number of field campaigns to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been made of emissions of Masaya (Nicaragua), Etna and Vulcano (Italy), Tatun (Taiwan), Taal and Makiling (Philippines) and Kilauea (Hawaii, USA). Emissions from open vents, fumaroles, hot springs, bubbling mud pools and altered ground were investigated at these sites. A Lumex 915+ portable mercury vapour spectrometer was employed to record real-time gaseous elemental mercury (GEM) concentrations alongside a Multi-G...
There is some debate at present regarding the quantity of mercury naturally released by volcanoes... more There is some debate at present regarding the quantity of mercury naturally released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget a number of field campaigns were carried out to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been
ABSTRACT The data on volcanic and non-volcanic gas emissions available online are, as today, inco... more ABSTRACT The data on volcanic and non-volcanic gas emissions available online are, as today, incomplete and most importantly, fragmentary. Hence, there is need for common frameworks to aggregate available data, in order to characterize and quantify the phenomena at various scales. Building on the Googas experience we are now extending its capability, particularly on the user side, by developing a new web environment for collecting and publishing data. We have started to create a new and detailed web database (MAGA: MApping GAs emissions) for the deep carbon degassing in the Mediterranean area. This project is part of the Deep Earth Carbon Degassing (DECADE) research initiative, lunched in 2012 by the Deep Carbon Observatory (DCO) to improve the global budget of endogenous carbon from volcanoes. MAGA database is planned to complement and integrate the work in progress within DECADE in developing CARD (Carbon Degassing) database. MAGA database will allow researchers to insert data interactively and dynamically into a spatially referred relational database management system, as well as to extract data. MAGA kicked-off with the database set up and a complete literature survey on publications on volcanic gas fluxes, by including data on active craters degassing, diffuse soil degassing and fumaroles both from dormant closed-conduit volcanoes (e.g., Vulcano, Phlegrean Fields, Santorini, Nysiros, Teide, etc.) and open-vent volcanoes (e.g., Etna, Stromboli, etc.) in the Mediterranean area and Azores. For each geo-located gas emission site, the database holds images and description of the site and of the emission type (e.g., diffuse emission, plume, fumarole, etc.), gas chemical-isotopic composition (when available), gas temperature and gases fluxes magnitude. Gas sampling, analysis and flux measurement methods are also reported together with references and contacts to researchers expert of the site. Data can be accessed on the network from a web interface or as a data-driven web service, where software clients can request data directly from the database. This way Geographical Information Systems (GIS) and Virtual Globes (e.g., Google Earth) can easily access the database, and data can be exchanged with other database. In details the database now includes: i) more than 1000 flux data about volcanic plume degassing from Etna (4 summit craters and bulk degassing) and Stromboli volcanoes, with time averaged CO2 fluxes of ~ 18000 and 766 t/d, respectively; ii) data from ~ 30 sites of diffuse soil degassing from Napoletan volcanoes, Azores, Canary, Etna, Stromboli, and Vulcano Island, with a wide range of CO2 fluxes (from les than 1 to 1500 t/d) and iii) several data on fumarolic emissions (~ 7 sites) with CO2 fluxes up to 1340 t/day (i.e., Stromboli). When available, time series of compositional data have been archived in the database (e.g., for Campi Flegrei fumaroles). We believe MAGA data-base is an important starting point to develop a large scale, expandable data-base aimed to excite, inspire, and encourage participation among researchers. In addition, the possibility to archive location and qualitative information for gas emission/sites not yet investigated, could stimulate the scientific community for future researches and will provide an indication on the current uncertainty on deep carbon fluxes global estimates.
The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in ... more The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in phosphate rock using a dedicated analytical instrument (the DMA80 Tricell by Milestone) that employs an integrated sequence of thermal decomposition followed by catalyst conversion, amalgamation and atomic absorption spectrophotometry. However, this instrument underestimates Hg concentrations when phosphorite and apatite rocks are investigated with a classic thermal decomposition treatment that complies with US EPA method 7473. Therefore, to improve the recovery of total Hg, we performed alkaline fusion digestion (AFD) directly inside the furnace of the instrument, using BCR(32) as a certified reference material (Moroccan phosphate rock--phosphorite). The salts used for the AFD were a mixture of Na2CO3, K2CO3 and Li2CO3, which melt at about 400°C, due to their ability to form a ternary eutectic and to decompose the phosphorite matrices at 700°C. By adopting this analytical approach, the Hg recovery in BCR(32) was about 100%, compared to 40% when the reference material was analysed without using the alkaline fusion salt. We suggest that the AFD allowed the decomposition of the sample matrix and that some Hg compounds linked with other functional groups may be transformed in carbonates that sublimate at lower temperatures than other Hg compounds. This original method was tested on a number of different geological samples to compare the differences between the AFD method and the thermal treatment in order to verify the working range and to check the robustness of the new approach.
Geological Society, London, Special Publications, 2014
ABSTRACT We review the state of knowledge on global volcanogenic Hg emissions to the atmosphere a... more ABSTRACT We review the state of knowledge on global volcanogenic Hg emissions to the atmosphere and present new data from seven active volcanoes (Poa´s, Rinco´n de la Vieja, Turrialba, Aso, Mutnovsky, Gorely and Etna) and two geothermal fields (Las Pailas and Las Hornillas). The variability of Hg contents (c. 4–125 ng m23) measured in gaseous emissions reflects the dynamic nature of volcanic plumes, where the abundances of volatiles are determined by the physical nature of degassing and variable air dilution. Based on our dataset and previous work, we propose that an average Hg/SO2 plume mass ratio of c. 7.8 × 1026 (+1.5 × 1026; 1 SE, n ¼ 13) is best representative of open-conduit quiescent degassing. Taking into account the uncertainty in global SO2 emissions, we infer a global volcanic Hg flux from persistent degassing of c. 76+30 t a21. Our data are derived from active volcanoes during non-eruptive periods and we do not have any direct constraint on the Hg flux during periods of elevated SO2 flux associated with large-scale effusive or explosive eruptions. This suggests that the time-averaged Hg flux from these volcanoes is even larger if the eruptive contribution is considered. Conversely, closed-conduit degassing and geothermal emissions contribute modest amounts of Hg.
There is an urgent need to better constrain the global rates of mercury degassing from natural so... more There is an urgent need to better constrain the global rates of mercury degassing from natural sources, including active volcanoes. Hitherto, estimates of volcanic fluxes have been limited by the poorly determined speciation of Hg in volcanic emissions. Here, we present a systematic characterisation of mercury partitioning between gaseous (Hg (g)) and particulate (Hg (p)) forms in the volcanic plume of Mount Etna, the largest open-vent passively degassing volcano on Earth. We demonstrate that mercury transport is predominantly in the gas phase, with a mean Hg (p) /Hg (g) ratio of $0.01 by mass. We also present the first simultaneous measurement of divalent gaseous mercury (Hg II ðgÞ) and total gaseous mercury (Hg (g)) in a volcanic plume, which suggests that Hg 0 ðgÞ is the prevalent form of mercury in this context. These data are supported by the results of model simulations, carried out with HSC thermodynamic software. Based on a mean ''bulk plume'' Hg/SO 2 mass ra...
There is some debate at present regarding the quantity of mercury naturally released by volcanoes... more There is some debate at present regarding the quantity of mercury naturally released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget a number of field campaigns were carried out to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been made of emissions of Masaya (Nicaragua), Etna and Vulcano (Italy), Tatun (Taiwan), Taal and Makiling (Philippines) and Kilauea (Hawaii, USA). Emissions from open vents, fumaroles, hot springs, bubbling mud pools and altered ground were investigated at these sites and concentrations of mercury elevated above background levels were observed on most occasions. A Lumex 915+ portable mercury vapour spectrometer was employed to record real-time gaseous elemental mercury (GEM) concentrations alongside a Multi-GAS sensor box developed to monitor SO2, H2S, CO2, humidity, temperature and pressure. These measurements were carried out...
Since the 19 March 2008 explosion within Halema`uma`u that formed the new vent at Kilauea's s... more Since the 19 March 2008 explosion within Halema`uma`u that formed the new vent at Kilauea's summit, degassing rates have been greatly elevated above the levels typical of previous years. The location and subsequent dispersion of this new degassing presents its own specific problems compared to that in the east rift zone. For example, throughout 2008 the Halema'uma'u plume was generally blown through the Kau desert, directly affecting downwind communities. In this study we present measurements made in July 2008. We characterize the gas chemistry in terms of SO2 and halogens (HF, HCl, HBr and HI) in the new plume from Halema'uma'u in order to compare them with other plumes worldwide, including those from subduction zone settings and other emissions from Kilauea itself. Further to this we characterize the plume's chemistry in terms of emissions of environmentally important metallic species both in the size-segregated aerosol (important for determining atmospheri...
Mercury is a toxic metal which has a long lifetime in the atmosphere, (~ 1 year). This long lifet... more Mercury is a toxic metal which has a long lifetime in the atmosphere, (~ 1 year). This long lifetime enables it to be carried vast distances and the metal is found in elevated concentrations in remote regions of the world. There is some debate at present regarding the quantity of mercury released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget we have carried out a number of field campaigns to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been made of emissions of Masaya (Nicaragua), Etna and Vulcano (Italy), Tatun (Taiwan), Taal and Makiling (Philippines) and Kilauea (Hawaii, USA). Emissions from open vents, fumaroles, hot springs, bubbling mud pools and altered ground were investigated at these sites. A Lumex 915+ portable mercury vapour spectrometer was employed to record real-time gaseous elemental mercury (GEM) concentrations alongside a Multi-G...
There is some debate at present regarding the quantity of mercury naturally released by volcanoes... more There is some debate at present regarding the quantity of mercury naturally released by volcanoes and its relative significance to the natural Hg budget. In order to better understand the role of volcanoes in the global mercury budget a number of field campaigns were carried out to evaluate the Hg/S ratios in volcanic gases around the world. Measurements have been
ABSTRACT The data on volcanic and non-volcanic gas emissions available online are, as today, inco... more ABSTRACT The data on volcanic and non-volcanic gas emissions available online are, as today, incomplete and most importantly, fragmentary. Hence, there is need for common frameworks to aggregate available data, in order to characterize and quantify the phenomena at various scales. Building on the Googas experience we are now extending its capability, particularly on the user side, by developing a new web environment for collecting and publishing data. We have started to create a new and detailed web database (MAGA: MApping GAs emissions) for the deep carbon degassing in the Mediterranean area. This project is part of the Deep Earth Carbon Degassing (DECADE) research initiative, lunched in 2012 by the Deep Carbon Observatory (DCO) to improve the global budget of endogenous carbon from volcanoes. MAGA database is planned to complement and integrate the work in progress within DECADE in developing CARD (Carbon Degassing) database. MAGA database will allow researchers to insert data interactively and dynamically into a spatially referred relational database management system, as well as to extract data. MAGA kicked-off with the database set up and a complete literature survey on publications on volcanic gas fluxes, by including data on active craters degassing, diffuse soil degassing and fumaroles both from dormant closed-conduit volcanoes (e.g., Vulcano, Phlegrean Fields, Santorini, Nysiros, Teide, etc.) and open-vent volcanoes (e.g., Etna, Stromboli, etc.) in the Mediterranean area and Azores. For each geo-located gas emission site, the database holds images and description of the site and of the emission type (e.g., diffuse emission, plume, fumarole, etc.), gas chemical-isotopic composition (when available), gas temperature and gases fluxes magnitude. Gas sampling, analysis and flux measurement methods are also reported together with references and contacts to researchers expert of the site. Data can be accessed on the network from a web interface or as a data-driven web service, where software clients can request data directly from the database. This way Geographical Information Systems (GIS) and Virtual Globes (e.g., Google Earth) can easily access the database, and data can be exchanged with other database. In details the database now includes: i) more than 1000 flux data about volcanic plume degassing from Etna (4 summit craters and bulk degassing) and Stromboli volcanoes, with time averaged CO2 fluxes of ~ 18000 and 766 t/d, respectively; ii) data from ~ 30 sites of diffuse soil degassing from Napoletan volcanoes, Azores, Canary, Etna, Stromboli, and Vulcano Island, with a wide range of CO2 fluxes (from les than 1 to 1500 t/d) and iii) several data on fumarolic emissions (~ 7 sites) with CO2 fluxes up to 1340 t/day (i.e., Stromboli). When available, time series of compositional data have been archived in the database (e.g., for Campi Flegrei fumaroles). We believe MAGA data-base is an important starting point to develop a large scale, expandable data-base aimed to excite, inspire, and encourage participation among researchers. In addition, the possibility to archive location and qualitative information for gas emission/sites not yet investigated, could stimulate the scientific community for future researches and will provide an indication on the current uncertainty on deep carbon fluxes global estimates.
The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in ... more The aim of this work was to develop a new method to determine the mercury (Hg) concentrations in phosphate rock using a dedicated analytical instrument (the DMA80 Tricell by Milestone) that employs an integrated sequence of thermal decomposition followed by catalyst conversion, amalgamation and atomic absorption spectrophotometry. However, this instrument underestimates Hg concentrations when phosphorite and apatite rocks are investigated with a classic thermal decomposition treatment that complies with US EPA method 7473. Therefore, to improve the recovery of total Hg, we performed alkaline fusion digestion (AFD) directly inside the furnace of the instrument, using BCR(32) as a certified reference material (Moroccan phosphate rock--phosphorite). The salts used for the AFD were a mixture of Na2CO3, K2CO3 and Li2CO3, which melt at about 400°C, due to their ability to form a ternary eutectic and to decompose the phosphorite matrices at 700°C. By adopting this analytical approach, the Hg recovery in BCR(32) was about 100%, compared to 40% when the reference material was analysed without using the alkaline fusion salt. We suggest that the AFD allowed the decomposition of the sample matrix and that some Hg compounds linked with other functional groups may be transformed in carbonates that sublimate at lower temperatures than other Hg compounds. This original method was tested on a number of different geological samples to compare the differences between the AFD method and the thermal treatment in order to verify the working range and to check the robustness of the new approach.
Geological Society, London, Special Publications, 2014
ABSTRACT We review the state of knowledge on global volcanogenic Hg emissions to the atmosphere a... more ABSTRACT We review the state of knowledge on global volcanogenic Hg emissions to the atmosphere and present new data from seven active volcanoes (Poa´s, Rinco´n de la Vieja, Turrialba, Aso, Mutnovsky, Gorely and Etna) and two geothermal fields (Las Pailas and Las Hornillas). The variability of Hg contents (c. 4–125 ng m23) measured in gaseous emissions reflects the dynamic nature of volcanic plumes, where the abundances of volatiles are determined by the physical nature of degassing and variable air dilution. Based on our dataset and previous work, we propose that an average Hg/SO2 plume mass ratio of c. 7.8 × 1026 (+1.5 × 1026; 1 SE, n ¼ 13) is best representative of open-conduit quiescent degassing. Taking into account the uncertainty in global SO2 emissions, we infer a global volcanic Hg flux from persistent degassing of c. 76+30 t a21. Our data are derived from active volcanoes during non-eruptive periods and we do not have any direct constraint on the Hg flux during periods of elevated SO2 flux associated with large-scale effusive or explosive eruptions. This suggests that the time-averaged Hg flux from these volcanoes is even larger if the eruptive contribution is considered. Conversely, closed-conduit degassing and geothermal emissions contribute modest amounts of Hg.
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