Volcanic ash leaching as a means of tracing the environmental impact of the 2011 Grímsvötn eruption, Iceland

The Grímsvötn volcanic eruption, from 21 to 28 May, 2011, was the largest eruption of the Grímsvötn Volcanic System since 1873, with a Volcanic Explosivity Index (VEI) of magnitude 4. The main geochemical features of the potential environmental impact of the volcanic ash-water interaction were determined using two different leaching methods as proxies (batch and vertical flow-through column experiments). Ash consists of glass with minor amounts of plagioclase, clinopyroxene, diopside, olivine and iron sulphide; this latter mineral phase is very rare in juvenile ash. Ash grain morphology and size reflect the intense interaction of magma and water during eruption. Batch and column leaching tests in deionised water indicate that Na, K, Ca, Mg, Si, Cl, S and F had the highest potential geochemical fluxes to the environment. Release of various elements from volcanic ash took place immediately through dissolution of soluble salts from the ash surface. Element solubilities of Grímsvötn ash regarding bulk ash composition were <1 %. Combining the element solubilities and the total estimated mass of tephra (7.29 × 1014 g), the total inputs of environmentally important elements were estimated to be 8.91 × 109 g Ca, 7.02 × 109 g S, 1.10 × 109 g Cl, 9.91 × 108 g Mg, 9.91 × 108 g Fe and 1.45 × 108 g P The potential environmental problems were mainly associated with the release of F (5.19 × 109 g)We gratefully acknowledge the assistance of ICTJA-CSIC labGEOTOP (infrastructure co-funded by ERDF-EU Ref. CSIC08-4E-001) and DRX (infrastructure co-funded by ERDF-EU Ref. CSIC10-4E-141) Surveys (J. Ibañez, J. Elvira and S. Alvarez) and the CCiTUB (SEM Unit) in the analytical work. Financial support was provided by the QUECA Project (MINECO, CGL2011-23307). We appreciate the invaluable comments of Dr. N. Olgun on a previous version of the manuscript. This study was carried out in the framework of the Research Consolidated Groups GEOPAM (Generalitat de Catalunya, 2014 SGR 869) and GEOVOL and the Associated Unit CSIC-UB UAGEPE (UA 285P01)Peer reviewe

Ventajas y desventajas de la aplicación de la técnica de HR-ICP-MS al análisis inorgánico de aguas en terrenos volcánicos

La técnica de ICP-MS ha supuesto un gran avance en el análisis de aguas en los últimos decenios tal y como recogen las normativas al respecto en Europa, Estados Unidos, etc., habiéndose convertido en una técnica de referencia particularmente en el tema de calidad del agua. La alta resolución aplicada a la ICP-MS reduce considerablemente las interferencias y su combinación con detectores aptos para concentraciones mayoritarias hace que se disponga de una herramienta analítica muy competitiva que permite determinar simultáneamente elementos mayoritarios y trazas, incluidos halógenos (Cl, Br, I), y además relaciones isotópicas (ej., Li y B). Estos aproximadamente 60 parámetros geoquímicos permiten una caracterización exhaustiva de las aguas para temas de calidad y también ayudan a discernir más fácilmente el origen y el tránsito de las aguas a través de diferentes terrenos volcánicos. Por otra parte, la HR-ICP-MS es de gran aplicación a la determinación de los aportes geoquímicos volcanogénicos a los balances biogeoquímicos regionales, como por ejemplo de los materiales piroclásticos, a través del análisis de lixiviados procedentes de la simulación de la interacción del agua con estos productos eruptivos. En este trabajo se exponen los pros y contras de la aplicación de la HR-ICP-MS a aguas en problemáticas volcanogénicas a través de diferentes ejemplos (Islandia, Argentina, Chile, etc.). Agradecemos la asistencia del Servicio labGEOTOP (infraestructura cofinanciada por FEDER-UE, Ref. CSIC08-4E-001) del ICTJA-CSIC. La financiación fue proporcionada por QUECA (MINECO, CGL2011-23307). Este estudio se llevó a cabo en el marco del Grupo Reconocido GEOPAM (2014 SGR 869).La financiación fue proporcionada por QUECA (MINECO, CGL2011-23307). Este estudio se llevó a cabo en el marco del Grupo Reconocido GEOPAM (2014 SGR 869).Peer Reviewe

Impacto ambiental de la interacción agua-ceniza en la erupción del 2011 del volcán Grimsvötn (Islandia)

The Grímsvötn volcanic eruption, from 21 to 28 May, 2011, was the largest eruption of the Grímsvötn Volcanic System since 1873. The main geochemical features of the potential environmental impact of the volcanic ash-water interaction were determined using two different leaching methods as proxies (batch and vertical flow through column experiments). The main findings reveal that Na, K, Ca, Mg, Si, Cl, S and F show the largest geochemical fluxes caused by the interaction of water and ash. Additionally, the significant amounts of some of these elements (Ca, S and Mg) together with P, Cl, Fe, which are usually considered as macro/micronutrients, demonstrates the fertilising potential of the May 2011 emitted ash. On the other hand, release of F highlights the possible environmental problems arising from ash fallout on land or into fresh water syste ms. It is noteworthy that the chemical release is maximal during the first few hours of contact between tephra and water due to the dissolution of soluble salts from the ash surface. As time progresses, these constituents are exhausted, the release drops considerably and elements are freed instead by the incongruent dissolution of the volcanic glass.Este trabajo ha sido financiado por el proyecto QUECA (MINECO, CGL2011-23307).Peer Reviewe

The ongoing volcanic eruption of El Hierro, Canary Islands

El Hierro, the youngest of the Canary Islands (Spain), is no stranger to hazards associated with volcanic activity or to efforts to minimize the effects of these hazards on local communities. As early as 1793, administrative records of El Hierro indicate that a swarm of earthquakes was felt by locals; fearing a greater volcanic catastrophe, the first evacuation plan of an entire island in the history of the Canaries was prepared. The 1793 eruption was probably submarine with no appreciable consequences other than that the earthquakes were felt [Carracedo, 2008]; over the next roughly 215 years the island was seismically quiet. Yet seismic and volcanic activity are expected on this youngest Canary Island due to its being directly above the presumed location of the Canary Island hot spot, a mantle plume that feeds upwelling magma just under the surface, similar to the Hawaiian Islands. Because of this known geologic activity, the Spanish Instituto Geogrfco Nacional (IGN) has managed geophysical monitoring of the island since the beginning of the 1990s.Peer Reviewe

Caracterización geoquímica de los sedimentos de la red de drenaje del Rio Garona en la Val d'Aran (Catalunya, España).

A geochemical survey of stream sediments from the Garona River was performed in order to define the main regional lithogeochemical units and, based on this geochemical exploration study, to establish the reference levels of some chemical elements in the upper Garona River basin. The analysis of the lower grainsize fraction (˂180 μm) by HR-ICP-MS of 33 stream sediment samples allowed us establish reference levels for 48 elements. We have also studied the leachates of the sediments to model the environmentally available geochemical fraction. The trace elements with the lowest reference level, ranging between 10 and 50 mg/kg, are Th, Pr, Ga, Y, Ni, Pb, As, Cu, Zr, Li, Cr, Nd, La, and V. Instead, Zn, Rb, Sr, Ce and Ba show concentrations higher than 50 mg/kg. Some enrichments were observed in the streams sediments according to the three main litogeochemical units defined; the Maladeta-Marimanya granitoids (higher concentrations of Y, Th, Pb and U), the metasediments of an extensive area of the basin (enrichments in Pb, Sr and Sn), and the black shales (in Cu, U, Sr, Ni, Zn, V, Sb and Mo) which are present in local areas of the basin.SíPeer Reviewe

Los depósitos de ceniza volcánica del Pleistoceno Superior-Holoceno de la región de Tafí del Valle-Cafayate, noroeste de Argentina

[EN]We identified volcanic ash deposits, whose thickness can exceed sometimes the 4 m, in the southeastern margin of La Puna and neighbouring areas (Provinces of Tucuman and Salta, Argentina). These Late Pleistocene and Holocene deposits show the existence of a highly explosive volcanism only some few thousand years ago, without comparison with any historical volcanic episode in northwestern Argentina. We have characterized the size distribution of ash (laser diffraction), morphology of particles (SEM), mineralogy (XRD) and the geochemistry of major and trace elements in bulk sample using mass spectrometry (HR-ICP-MS). The information provided by these deposits is of great interest to size adequately the geochemical impact models of ashfall in future volcanic eruptions in the Central Volcanic Zone of the Andes, quantifying the contribution of volcanic ash to the regional geochemical balances, both with respect to nutrients (e.g., Ca and Fe) and potentially toxic elements (e.g., As and F), among other elements of interest.[ES] Se han localizado diversos depósitos de ceniza volcánica, cuyos espesores llegan a superar en ocasiones los 4 m al suroeste de La Puna y áreas limítrofes (Provincias de Tucumán y Salta, Argentina). Estos depósitos son de edad Pleistoceno Superior y Holoceno y muestran la existencia hace pocos miles de años de volcanismo altamente explosivo, sin comparación con ningún episodio volcánico histórico en el noroeste de Argentina. Se han caracterizado la distribución granulométrica de la ceniza (difracción laser), la morfología de las partículas (microscopía electrónica de barrido), mineralogía (difracción de rayos X) y la geoquímica de elementos mayores y trazas en muestra total mediante espectrometría de masas (HR-ICP-MS). La información suministrada por estos depósitos tiene gran interés a la hora de dimensionar los modelos de impacto geoquímico de la caída de ceniza de futuras erupciones volcánicas en la Zona Volcánica Central de los Andes, cuantificando la contribución de la ceniza volcánica a los balances geoquímicos regionales, tanto por lo que respecta a nutrientes (p. ej., Ca y Fe), como de elementos potencialmente tóxicos (p. ej., As y F), entre otros elementos de interés.Agradecemos el apoyo técnico del labGEOTOP (infraestructura cofinanciada por FEDER, CSIC08-4E-001) del ICTJA-CSIC; de los Grupos PEGEFA (2009-SGR-972) y GEOVOL y fue financiado por el Proyecto QUECA (CGL2011-23307).Peer reviewe

Mineralogical characterization of silica sinters from the El Tatio geothermal field, Chile

11 páginas.Silica sinters, deposited from alkali chloride waters in the El Tatio geothermal field in northern Chile (22°20'S, 68°01'W), have been characterized by XRD, SEM, TG-DTA, and FTIR. The dominant silica phase is opal-A. Minor contents of opal-A/-CT and opal-CT are also present together with halite (NaCl), sylvite (KCl), and realgar (AsS). Accessory phases include teruggite [Ca4MgAs2B12O22(OH)12·12(H2O)], sassolite (H3BO3), and detrital quartz (SiO2). FWHM values reflect the immature nature of the studied opal-A. DTA heating experiments of opal-A show cristobalite crystallization at ~1000 °C, whereas DTA cooling experiments show the β -alfacristobalite transformation at ~200 °C. The total weight loss is related to changes in the sinter microtextures, mineral phases, and organic matter contents. FTIR spectra show the effects of silica maturation as consequence of the loss of trapped and absorbed water attached to silanols.Peer reviewe

Influencia de las condiciones experimentales en la determinación de S, Cl, Br y I en agua por espectrometría de masas de alta resolución (HR-ICP-MS)

A systematic study was undertaken to optimize a method to determine S, Cl, Br and I in water by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS). The sample composition and preparation conditions (the total dissolved solids -TDS-, the total organic compounds -TOC- and the addition of nitric acid) were evaluated to assess the sample matrix influence. Furthermore, the effect of instrumental parameters (carrier gas flow rate, sample flow rate, radiofrequency -RF- power and analyzer resolution) was also studied to minimize the contribution of polyatomic species, and to establish the required resolution. Low, medium or high resolutions were compared in terms of background level and sensitivity. After optimization, a multivariate robustness test was carried out by means of a Placket-Burman design. This method was applied to samples of the Llobregat and Ter rivers which are used for the drinking water system of the Metropolitan Area of Barcelona (~4.5 million inhabitants), Catalonia, northeast Spain.Este estudio fue financiado a través del Proyecto QUECA del Ministerio de Economía y Competitividad de España (CGL2011-23307) y el Proyecto PICT-2013-1259 (FONCyT, Argentina). Los análisis se realizaron en el Laboratorio de Geoquímica labGEOTOP en el ICTJA CSIC, infraestructura cofinanciada por FEDER-UE(Ref. CSIC08-4E-001).Peer Reviewe

Caracterización y clasificación de los carbones cretácicos de Teruel. Relaciones entre sus características y el entorno geológico

27 páginas, 8 figuras, 4 tablas.[ES]: Se han caracterizado los carbones cretácicos de la cuenca minera de Teruel (España), mediante el estudio exhaustivo de 36 muestras de capa de todas las explotaciones con actividad minera. El estudio ha comprendido: Análisis inmediato, elemental y petrográfico. Asimismo, se han determinado otros parámetros cuyo conocimiento se consideró necesario. También se han realizado ensayos carboquimicos como oxidación e hidrogenación. Los resultados muestran que aunque estos carbones pertenecen todos a una misma unidad geológica (Formación Escucha), existen diferencias claras entre los carbones de las subzonas Norte y Sur del Distrito Minero. Estos carbones se han clasificado mediante sistemas científicos (Seyler, van Krevelen y Alpem-ICCP) y comerciales (ECE/IJN y ASTM). El mejor parámetro clasificatorio ha sido la reflectividad de la vitrinita. Según el sistema de clasificación utilizado, los carbones de la subzona Norte se pueden considerar como lignitos o subbituminosos B y los de la subzona Sur como subbituminosos B ó A. Las diferencias encontradas entre los carbones estudiados, se explican desde un punto de vista geológico, por dos motivos: 1) Diferente presión litostática sobre las capas de carbón según la subzona, debido al aumento progresivo de la potencia de los sedimentos del Cenomaniense - Senoniense (Cretácico Superior) de Norte a Sur del Distrito Minero. 2) Menor influencia de la orogénesis alpina en las subzona Norte, contrastando con la subzona Sur, donde provocó gran número de fallas y plegamientos (una estructuración más intensa de las sucesiones mesozoicas).[EN]: Cretaceous coals from the Teruel Mining District (Spain) have been characterized by an exhaustive study of 36 bed samples from alí of the underground and upen cut mines with activity in that cual field. This study has included proximate, elemental, petrographic and other analyses. Also, sume chemical tests, as oxidations and hydrogenations, have been carried out. The results show that although these coals belung tu the same geological unit (Escucha Furmation in the lower Cretaceous), there are clear differences between the Norther and Southem Subzones of the Mining District. These coals have been classified by sume scientific (Syler’s, van Krevelen diagram and Alpem-ICCP) and commercial (ECE/UN and ASTM) systems. The best parameter tu classify these coals has been the vitrinite reflectance. In depending un the used classification system, cuaN from the North Subzone can be cunsidered as lignites or subbituminous B while coals from the South Subzone can be considered as subbituminous B or A. The differences between both groups uf studied coals can be explained, from a geological viewpoint, by two major factors: 1) The lithostatic pressure supported by the cual beds has been different in depending un the Subzone, because of the progressive thickness increase of te Cenomanian - Senonian sediments (Upper Cretaceous) from the North tu the South uf the Mining District. 2) The intensity of te Alpine Orogeny was stronger in the South Subzone; where gaye rise tu a more intense structuration of the Mesozoic sequences.El proyecto de investigación: “Caracterización de carbones aragoneses” del que forma parte este proyecto, fue realizado en el Instituto de Carboquímica, gracias a la financiación del CSIC, OCICARBON y Diputación General de Aragón - Diputación Provincial de Teruel (Juan, 1990).Peer reviewe

Coexistence of calc-alkaline and ultrapotassic alkaline magmas at Mounts Cimini : evidence for transition from the Tuscan to the Roman Magmatic Provinces (central Italy)

The volcanic complex of Mts. Cimini (~0.90-1.30Ma) represents the geographical and chronological transition between the Tuscan Magmatic Province (TMP) and the Roman Magmatic Province (RMP), in central Italy. Major and trace elements, and Sr, Nd and Pb isotopes of whole-rock, as well as mineral chemistry analyses, were carried out on samples representative of the different petrographic and chronological units of Mts. Cimini. In particular, we focused on the olivine-bearing latites of Mts. Cimini that are the most mafic magmas, belong to the last phase of this volcanic activity, and are heterogeneous in highly incompatible element ratios and Sr-isotope compositions. We suggest that such heterogeneity reflects the occurrence of a heterogeneous upper mantle beneath central Italy, in which different portions, e.g., the sources of both the TMP and RMP, are characterized by distinct geochemical and petrographic features. In this scenario, about 900ka ago, the olivine-bearing latites mark the progressive decline of the TMP magma production in favour of partial melting of the RMP mantle region, thus recording the coexistence of both ultrapotassic alkaline and calc-alkaline magmas in the same volcanic region