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Open accessPosted ContentDOI: 10.5194/ACP-2020-284

Halogen activation in the plume of Masaya volcano: field observations and box model investigations

04 Mar 2021-Atmospheric Chemistry and Physics (Copernicus GmbH)-Vol. 21, Iss: 5, pp 3371-3393
Abstract: . Volcanic emissions are a source of halogens to the atmosphere. Rapid reactions convert the initially emitted hydrogen halides (HCl, HBr, HI) into reactive species e.g. BrO, Br2, BrCl, ClO, OClO and IO. The activation reaction mechanisms in the plume consume ozone (O3), which is entrained by in-mixed ambient air. In this study, we present observations of the oxidation of bromine, chlorine and iodine during the first 11 minutes after emission, investigating the plume of Santiago Crater of Masaya volcano in Nicaragua. Two field campaigns were conducted, in July 2016 and September 2016. The sum of the reactive species of the respective halogens were determined by gas diffusion denuder sampling followed by GC-MS analysis, while the total amounts of halogens and sulfur amounts were obtained by alkaline trap sampling with subsequent IC and ICP-MS measurements. Both ground and airborne sampling with an unmanned aerial vehicle (including a denuder sampler in combination with an electrochemical SO2 sensor) was performed at different distances from the crater rim. The in-situ measurements were accompanied by remote sensing observations (DOAS). For bromine, the reactive fraction increased from 0.20 ± 0.13 at the crater rim to 0.76 ± 0.26 at 2.8 km downwind, while chlorine showed an increase of the reactive fraction from (2.7 ± 0.7) × 10−4 to (11 ± 3) × 10−4 in the first 750 m. Additionally, a reactive iodine fraction of 0.3 at the crater rim and 0.9 at 2.8 km was measured. No significant increase in BrO / SO2 molar ratios was observed with the estimated age of the observed plume ranging from 1.4 min to 11.1 min. This study presents a comprehensive gas diffusion denuder data set on reactive halogen species and compares BrO / SO2 ratios with the sum of all reactive Br species. With the observed field data, a chemistry box model (CAABA/MECCA) enabled the reproduction of the observed progression of the reactive bromine to total bromine ratio. An observed contribution of BrO to the reactive bromine fraction of about 10 % was reproduced in the first minutes of the model run. The model results emphasize the importance of ozone entrainment into the plume for the reproduction of the measured reactive bromine formation and the dependence on the availability of HXOY and NOX.

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Topics: Bromine (51%), Plume (50%)

7 results found

Open accessJournal ArticleDOI: 10.5194/AMT-14-4255-2021
Bo Galle1, Santiago Arellano1, Nicole Bobrowski2, Nicole Bobrowski3  +15 moreInstitutions (8)
Abstract: . A multi-rotor drone has been adapted for studies of volcanic gas plumes. This adaptation includes improved capacity for high-altitude and long-range, real-time SO2 concentration monitoring, long-range manual control, remotely activated bag sampling and plume speed measurement capability. The drone is capable of acting as a stable platform for various instrument configurations, including multi-component gas analysis system (MultiGAS) instruments for in situ measurements of SO2 , H2S , and CO2 concentrations in the gas plume and portable differential optical absorption spectrometer (MobileDOAS) instruments for spectroscopic measurement of total SO2 emission rate, remotely controlled gas sampling in bags and sampling with gas denuders for posterior analysis on the ground of isotopic composition and halogens. The platform we present was field-tested during three campaigns in Papua New Guinea: in 2016 at Tavurvur, Bagana and Ulawun volcanoes, in 2018 at Tavurvur and Langila volcanoes and in 2019 at Tavurvur and Manam volcanoes, as well as in Mt. Etna in Italy in 2017. This paper describes the drone platform and the multiple payloads, the various measurement strategies and an algorithm to correct for different response times of MultiGAS sensors. Specifically, we emphasize the need for an adaptive flight path, together with live data transmission of a plume tracer (such as SO2 concentration) to the ground station, to ensure optimal plume interception when operating beyond the visual line of sight. We present results from a comprehensive plume characterization obtained during a field deployment at Manam volcano in May 2019. The Papua New Guinea region, and particularly Manam volcano, has not been extensively studied for volcanic gases due to its remote location, inaccessible summit region and high level of volcanic activity. We demonstrate that the combination of a multi-rotor drone with modular payloads is a versatile solution to obtain the flux and composition of volcanic plumes, even for the case of a highly active volcano with a high-altitude plume such as Manam. Drone-based measurements offer a valuable solution to volcano research and monitoring applications and provide an alternative and complementary method to ground-based and direct sampling of volcanic gases.

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Topics: Volcanic Gases (53%), Volcano (50%), Plume (50%)

4 Citations

Open access
01 Apr 2017-
Abstract: Volcanoes release large amounts of reactive trace gases including sulfur and halogen-containing species into the atmosphere. The knowledge of halogen chemistry in volcanic plumes can deliver information about subsurface processes and is relevant for the understanding of the impact of volcanoes on atmospheric chemistry. In this study, a gas diffusion denuder sampling method using 1,3,5-trimethoxybenzene (1,3,5-TMB)-coated glass tubes for the in situ derivatization of reactive halogen species (RHS) was characterized by a series of laboratory experiments. The coating proved to be applicable to collect selectively gaseous bromine species with oxidation states (OS) of +1 or 0 (such as Br2, BrCl, HOBr, BrO, and BrONO2) while being unreactive to HBr (OS −1). The reaction of 1,3,5-TMB with reactive bromine species forms 1-bromo-2,4,6-TMB—other halogens give corresponding derivatives. Solvent elution of the derivatives followed by analysis with GC-MS results in absolute detection limits of a few nanograms for Br2, Cl2, and I2. In 2015, the technique was applied on volcanic gas plumes at Mt. Etna (Italy) measuring reactive bromine mixing ratios between 0.8 and 7.0 ppbv. Total bromine mixing ratios between 4.7 and 27.5 ppbv were derived from alkaline trap samples, simultaneously taken by a Raschig tube and analyzed with IC and ICP-MS. This leads to the first results of the reactive bromine contribution to total bromine in volcanic emissions, spanning over a range between 12% (±1) and 36% (±2). Our finding is in an agreement with previous model studies, which imply values <44% for plume ages <1 min, which is consistent with the assumed plume age at the sampling sites.

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Topics: Trace gas (56%), Bromine (51%), Halogen (51%)

3 Citations

Open accessJournal ArticleDOI: 10.5194/AMT-14-6395-2021
Abstract: . The chemical characterization of volcanic gas emissions gives insights into the interior of volcanoes. Bromine species have been correlated with changes in the activity of a volcano. In order to exploit the volcanic bromine gases, we need to understand what happens to them after they are outgassed into the atmosphere. This study aims to shed light on the conversion of bromospecies after degassing. The method presented here allows for the specific analysis of gaseous hydrogen bromide (HBr) in volcanic environments. HBr is immobilized by reaction with 5,6-epoxy-5,6-dihydro-[1,10]-phenanthroline (EP), which acts as an inner coating inside of diffusion denuder tubes (in situ derivatization). The derivative is analyzed by high-performance liquid chromatography coupled to electrospray ionization mass spectrometry (HPLC-ESI-MS). The collection efficiency for HBr (99.5 %), the collection efficiency for HBr alongside HCl (98.1 %), and the relative standard deviation of comparable samples (8 %) have been investigated. The comparison of the new denuder-based method and Raschig tubes as alkaline traps resulted on average in a relative bias between both methods of 10 ± 6 %. The denuder sampling setup was applied in the plume of Masaya (Nicaragua) in 2016. HBr concentrations in the range between 0.44 and 1.97 ppb were measured with limits of detection and quantification below 0.1 and 0.3 ppb respectively. The relative contribution of HBr as a fraction of total bromine decreased from 75 ± 11 % at the Santiago crater (214 m distance to the volcanic emission source) to 36 ± 8 % on the Nindiri rim (740 m distance). A comparison between our data and the previously calculated HBr, based on the CAABA/MECCA box model, showed a slightly higher trend for the HBr fraction on average than expected from the model. Data gained from this new method can further refine model runs in the future.

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Topics: Bromine (51%)

3 Citations

Open accessJournal ArticleDOI: 10.5194/ACP-21-9367-2021
Florian Dinger1, Florian Dinger2, Timo Kleinbek2, Steffen Dörner1  +8 moreInstitutions (2)
Abstract: . Masaya volcano (Nicaragua, 12.0° N, 86.2° W, 635 m a.s.l.) is one of the few volcanoes hosting a lava lake, today. We present continuous time series of SO2 emission fluxes and BrO / SO2 molar ratios in the gas plume of Masaya from March 2014 to March 2020. This study has two foci: (1) discussing the state of the art of long-term SO2 emission flux monitoring on the example of Masaya and (2) the provision and discussion of a continuous dataset on volcanic gas data unique in its temporal coverage, which poses a major extension of the empirical data base for studies on the volcanologic as well as atmospheric bromine chemistry. Our SO2 emission flux retrieval is based on a comprehensive investigation of various aspects of the spectroscopic retrievals, the wind conditions, and the plume height. Our retrieved SO2 emission fluxes are on average a factor of 1.4 larger than former estimates based on the same data. We furthermore observed a correlation between the SO2 emission fluxes and the wind speed when several of our retrieval extensions are not applied. We make plausible that such a correlation is not expected and present a partial correction of this artefact via applying dynamic estimates for the plume height as a function of the wind speed (resulting in a vanishing correlation for wind speeds larger than 10 m/s). Our empirical data set covers the three time periods (1) before the lava lake elevation, (2) period of high lava lake activity (December 2015–May 2018), (3) after the period of high lava lake activity. For these three time periods, we report average SO2 emission fluxes of 1000 ± 200 t d−1, 1000 ± 300 t d−1, and 700 ± 200 t d−1 and average BrO / SO2 molar ratios of (2.9 ± 1.5) × 10−5, (4.8 ± 1 : 9) ×10−5, and (5.5 ± 2–6) × 10−5. These variations indicate that the two gas proxies provide complementary information: the BrO / SO2 molar ratios were susceptible in particular for the transition between the two former periods while the SO2 emission fluxes were in particular susceptible for the transition between the two latter time periods. We observed an extremely significant annual cyclicity for the BrO / SO2 molar ratios (amplitudes between 1–4–2–6 × 10−5) with a weak semi-annual modulation. We suggest that this cyclicity might be a manifestation of meteorological cycles. We found an anti-correlation between the BrO / SO2 molar ratios and the atmospheric water concentration (correlation coefficient of −47 %) but in contrast to that neither a correlation with the ozone mixing ratio (+21 %) nor systematic dependencies between the BrO / SO2 molar ratios and the atmospheric plume age for an age range of 2–20 min after the release from the volcanic edifice. The two latter observations indicate an early stop of the autocatalytic partial transformation of bromide Br− solved in aerosol particles to atmospheric BrO. Further patterns in the BrO / SO2 time series were (1) a step increase by 0.7 × 10−5 in late 2015, (2) a linear trend of 1.2 × 10−5 per year from December 2015 to March 2018, and (3) a linear trend of −0.8 × 10−5 per year from June 2018 to March 2020. The step increase in 2015 coincided with the 55 elevation of the lava lake and was thus most likely caused by a change in the magmatic system. The linear trend between late 2015 and early 2018 may indicate the evolution of the magmatic gas phase during the ascent of juvenile gas-rich magma whereas the linear trend from June 2018 on may indicate a decreasing bromine abundance in the magma.

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Topics: Lava (53%), Volcano (51%), Plume (50%)

3 Citations

Open accessJournal ArticleDOI: 10.5194/ACP-21-12413-2021
Abstract: Volcanoes emit halogens into the atmosphere that undergo chemical cycling in plumes and cause destruction of ozone. The impacts of volcanic halogens are inherently difficult to measure at volcanoes, and the complexity of the chemistry, coupled with the mixing and dispersion of the plume, makes the system challenging to model numerically. We present aircraft observations of the Mount Etna plume in the summer of 2012, when the volcano was passively degassing. Measurements of SO 2-an indicator of plume intensity-and ozone were made in the plume a few 10s of km from the source, revealing a strong negative correlation between ozone and SO 2 levels. From these observations we estimate a mean in-plume ozone loss rate of 1.3 × 10 −5 molecules of O 3 per second per molecule of SO2. This value is similar to observation-derived estimates reported very close to the Mount Etna vents, indicating continual ozone loss in the plume up to at least 10's km downwind. The chemically reactive plume is simulated using a new numerical 3D model "WRF-Chem Volcano" (WCV), a version of WRF-Chem we have modified to incorporate volcanic emissions (including HBr and HCl) and multi-phase halogen chemistry. We used nested grids to model the plume close to the volcano at 1 km. The focus is on the early evolution of passively degassing plumes aged less than one hour and up to 10's km downwind. The model reproduces the so-called 'bromine explosion': the daytime bromine activation process by which HBr in the plume is converted to other more reactive forms that continuously cycle in the plume. These forms include the radical BrO, a species whose ratio with SO 2 is commonly measured in volcanic plumes as an indicator of halogen ozone-destroying chemistry. We track the modelled partitioning of bromine between its forms. The model yields in-plume BrO/SO 2 ratios (around 10 −4 mol/mol) similar to those observed previously in Etna plumes. The modelled BrO/SO 2 is lower in plumes which are more dilute (e.g. at greater windspeed). It is also slightly lower in plumes in the middle of the day compared than in the morning and evening, due to BrO's reaction with diurnally varying HO 2. Sensitivity simulations confirm the importance of near-vent products from high temperature chemistry, notably bromine radicals, in initiating the ambient temperature plume halogen cycling. Note also that heterogeneous reactions that activate bromine also activate a small fraction of the emitted chlorine; the resulting production of chlorine radical Cl causes a strong reduction in the methane lifetime and increasing formation of HCHO in the plume.

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Topics: Plume (60%), Volcano (51%)

2 Citations


101 results found

Journal ArticleDOI: 10.1038/NATURE00775
06 Jun 2002-Nature
Abstract: The formation of marine aerosols and cloud condensation nuclei—from which marine clouds originate—depends ultimately on the availability of new, nanometre-scale particles in the marine boundary layer. Because marine aerosols and clouds scatter incoming radiation and contribute a cooling effect to the Earth's radiation budget, new particle production is important in climate regulation. It has been suggested that sulphuric acid—derived from the oxidation of dimethyl sulphide—is responsible for the production of marine aerosols and cloud condensation nuclei. It was accordingly proposed that algae producing dimethyl sulphide play a role in climate regulation, but this has been difficult to prove and, consequently, the processes controlling marine particle formation remains largely undetermined. Here, using smog chamber experiments under coastal atmospheric conditions, we demonstrate that new particles can form from condensable iodine-containing vapours, which are the photolysis products of biogenic iodocarbons emitted from marine algae. Moreover, we illustrate, using aerosol formation models, that concentrations of condensable iodine-containing vapours over the open ocean are sufficient to influence marine particle formation. We suggest therefore that marine iodocarbon emissions have a potentially significant effect on global radiative forcing.

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Topics: Cloud condensation nuclei (56%), Marine biology (52%), Aerosol (51%) ... read more

641 Citations

Open accessJournal ArticleDOI: 10.5194/ACP-7-4375-2007
William R. Simpson1, R. von Glasow2, K. Riedel3, Philip S. Anderson4  +22 moreInstitutions (16)
Abstract: . During springtime in the polar regions, unique photochemistry converts inert halide salt ions (e.g. Br−) into reactive halogen species (e.g. Br atoms and BrO) that deplete ozone in the boundary layer to near zero levels. Since their discovery in the late 1980s, research on ozone depletion events (ODEs) has made great advances; however many key processes remain poorly understood. In this article we review the history, chemistry, dependence on environmental conditions, and impacts of ODEs. This research has shown the central role of bromine photochemistry, but how salts are transported from the ocean and are oxidized to become reactive halogen species in the air is still not fully understood. Halogens other than bromine (chlorine and iodine) are also activated through incompletely understood mechanisms that are probably coupled to bromine chemistry. The main consequence of halogen activation is chemical destruction of ozone, which removes the primary precursor of atmospheric oxidation, and generation of reactive halogen atoms/oxides that become the primary oxidizing species. The different reactivity of halogens as compared to OH and ozone has broad impacts on atmospheric chemistry, including near complete removal and deposition of mercury, alteration of oxidation fates for organic gases, and export of bromine into the free troposphere. Recent changes in the climate of the Arctic and state of the Arctic sea ice cover are likely to have strong effects on halogen activation and ODEs; however, more research is needed to make meaningful predictions of these changes.

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Topics: Tropospheric ozone depletion events (92%), Ozone depletion (59%), Atmospheric chemistry (55%) ... read more

534 Citations

Open accessJournal Article
Michael R. Carroll1, James D. Webster2Institutions (2)
Topics: Sulfur (55%), Fluorine (55%), Chlorine (52%)

403 Citations

Journal ArticleDOI: 10.1021/CR200029U
14 Mar 2012-Chemical Reviews
Abstract: Atmospheric Chemistry of Iodine Alfonso Saiz-Lopez,* John M. C. Plane,* Alex R. Baker, Lucy J. Carpenter, Roland von Glasow, Juan C. G omez Martín, Gordon McFiggans, and Russell W. Saunders Laboratory for Atmospheric and Climate Science (CIAC), CSIC, Toledo, Spain School of Chemistry, University of Leeds, Leeds, LS2 9JT, United Kingdom School of Environmental Sciences, University of East Anglia, Norwich NR4 7TJ, United Kingdom Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom School of Earth, Atmospheric & Environmental Sciences, University of Manchester, Manchester, M13 9PL, United Kingdom

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Topics: Atmospheric chemistry (60%)

321 Citations