Autoren:	Gutiérrez, Xochilt Bobrowski, Nicole Rüdiger, Julian Liotta, Marcello Geil, Bastien Hoffmann, Thorsten Gutiérrez, Eduardo Dinger, Florian Montalvo, Francisco Villalobos, Mirian Escobar, Demetrio
Titel:	Geochemical characterization of volcanic gas emissions at Santa Ana and San Miguel volcanoes, El Salvador, using remote-sensing and in situ measurements
Online-Publikationsdatum:	6-Jun-2023
Erscheinungsdatum:	2023
Sprache des Dokuments:	Englisch
Zusammenfassung/Abstract:	Volcanic degassing provides important information for the assessment of volcanic hazards. Santa Ana and San Miguel are open vent volcanoes along the Central American Volcanic Arc–CAVA, where the magmatism, basaltic to dacitic, is related to the near-orthogonal convergence of the Caribbean Plate and the subducting Cocos Plate. Both volcanoes are the most active ones in El Salvador with recent eruptive events in October 2005 (Santa Ana) and December 2013 (San Miguel), but still not much data on gas composition and emission are available today. At each volcano, SO2 emissions are regularly monitored using ground-based scanning Differential Optical Absorption Spectrometer (Scan-DOAS) instruments that are part of the global “Network for Observation of Volcanic and Atmospheric Change” (NOVAC). We used the data series from these NOVAC stations in order to retrieve SO2 and minimum bromine emissions, which can be retrieved from the same spectral data for the period 2006–2020 at Santa Ana and 2008–2019 at San Miguel. However, BrO was not detected above the detection limit. SO2 emission ranged from 10 to 7,760 t/d, and from 10 to 5,870 t/d for Santa Ana and San Miguel, respectively. In addition, the SO2 emissions are complemented with in situ plume data collected during regular monitoring surveys (2018–2020) and two field campaigns in El Salvador (2019 and 2020). MultiGAS instruments recorded CO2, SO2, H2S and H2 concentrations. We determined an average CO2/SO2 ratio of 2.9 ± 0.6 when peak SO2 concentration exceeded 15 ppmv at Santa Ana, while at San Miguel the CO2/SO2 ratio was 7.4 ± 1.8, but SO2 levels reached only up to 6.1 ppmv. Taking into account these ratios and the SO2 emissions determined in this study, the resulting CO2 emissions are about one order of magnitude higher than those determined so far for the two volcanoes. During the two field campaigns Raschig tubes (active alkaline trap) were used to collect plume samples which were analyzed with IC and ICP-MS to identify and quantify CO2, SO2, HCl, HF, and HBr. Additionally, also 1,3,5-trimethoxybenzene (TMB)-coated denuders were applied and subsequently analyzed by GC-MS to determine the sum of the reactive halogen species (RHS: including Cl2, Br2, interhalogens, hypohalous acids). The RHS to sulfur ratios at Santa Ana and San Miguel lie in the range of 10−5. Although no new insights could be gained regarding changes with volcanic activity, we present the most comprehensive gas geochemical data set of Santa Ana and San Miguel volcanoes, leading to a solid data baseline for future monitoring purposes at both volcanoes and their improved estimate of CO2, SO2 and halogens emissions. Determining the reactive fraction of halogens is a first step towards a better understanding of their effects on the atmosphere.
DDC-Sachgruppe:	540 Chemie 540 Chemistry and allied sciences
Veröffentlichende Institution:	Johannes Gutenberg-Universität Mainz
Organisationseinheit:	FB 09 Chemie, Pharmazie u. Geowissensch.
Veröffentlichungsort:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-9157
Version:	Published version
Publikationstyp:	Zeitschriftenaufsatz
Weitere Angaben zur Dokumentart:	Scientific article
Nutzungsrechte:	CC BY
Informationen zu den Nutzungsrechten:	https://creativecommons.org/licenses/by/4.0/
Zeitschrift:	Frontiers in Earth Science 11
Seitenzahl oder Artikelnummer:	1049670
Verlag:	Frontiers
Verlagsort:	Lausanne
Erscheinungsdatum:	2023
DOI der Originalveröffentlichung:	10.3389/feart.2023.1049670
Enthalten in den Sammlungen:	DFG-491381577-G