Instituto Volcanologico Of Canarias Involcan

Santa Cruz de Tenerife, Spain

Instituto Volcanologico Of Canarias Involcan

Santa Cruz de Tenerife, Spain
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Pina-Varas P.,University of Barcelona | Pina-Varas P.,Geological Survey of Spain | Ledo J.,University of Barcelona | Ledo J.,Instituto Volcanologico Of Canarias Involcan | And 5 more authors.
Surveys in Geophysics | Year: 2014

The resistivity structure of the Tenerife geothermal system has been determined by the 3-D inversion of data from different magnetotelluric surveys. In this paper, the ocean and topography effects on the magnetotelluric data were investigated by constructing a 3-D conceptual geoelectrical model of the island. The study showed that these effects should be taken into account in order to obtain a reliable subsurface model of the island. Data from 148 sites were used during three-dimensional inversion. The most interesting feature in the final geoelectrical model of the geothermal system is a low resistivity structure (<10 Ωm) above the resistive core of the system. The low resistivity structure has been interpreted as a hydrothermal clay alteration cap typically generated in the conventional geothermal systems. The resistivity model has been correlated with a recent seismic velocity model, showing that a low resistivity structure surrounds an area with high P wave velocity and medium-high resistivity. This medium-high resistivity area can be associated with a slowly solidified magma and, therefore, with a hotter part of the geothermal system. © 2014 Springer Science+Business Media Dordrecht.


Socas-Rodriguez B.,University of La Laguna | Herrera-Herrera A.V.,University of La Laguna | Asensio-Ramos M.,Instituto Volcanologico Of Canarias Involcan | Hernandez-Borges J.,University of La Laguna
Journal of Chromatography A | Year: 2014

Carbon nanotubes (CNTs) are still awakening scientists' interest because of their inherent properties as well as their applications in a wide variety of fields. Regarding Analytical Chemistry, and although they have also been used as stationary phases in chromatography or pseudostationary phases in capillary electrophoresis, they have also found a particular place in sorbent-based extraction techniques. In fact, they are currently used as sorbents in solid-phase extraction, solid-phase microextraction, stir-bar sorptive extraction and matrix solid-phase dispersion, for analyte enrichment or storage, sample fractionation or clean-up as well as support for derivatization reactions. CNT surface is tuneable and, as a result, they can be suitably functionalized, aggregated or linked to other supports which increase their potential use as sorbents. They can also be arranged under different formats (cartridges, fibers, stir bars, disks, etc.) or even combined with magnetic nanoparticles, which clearly enlarge their applications. This review article overviews the most recent applications of CNTs as sorbent materials, covering the period from 2010 to early 2014. © 2014 Elsevier B.V.


D'Orazio G.,CNR Methodological Chemistry Institute | D'Orazio G.,University of La Laguna | Asensio-Ramos M.,Instituto Volcanologico Of Canarias Involcan | Fanali C.,Biomedical University of Rome | And 2 more authors.
TrAC - Trends in Analytical Chemistry | Year: 2016

Capillary electrochromatography (CEC) is a miniaturized technique which gathers the high separation efficiency of capillary electrophoresis and the selectivity of liquid chromatography, being a very interesting hybrid separation procedure. It requires a small amount of solvents and samples, having a high impact in the total cost of the analysis. For these reasons, CEC has aimed a relatively big potential, especially in the fields of pharmaceutics and biomedicine analysis. Nonetheless, food analysis has also been of interest for a considerable number of researchers who have focused their efforts in this direction. This review article shows a deep examination of the use of CEC in food safety and food quality, from the first application in 1997 to the present, commenting those with a higher impact or novelty. © 2016 Elsevier B.V.


Doniz-Paez J.,University of La Laguna | Doniz-Paez J.,Instituto Volcanologico Of Canarias Involcan
Geomorphology | Year: 2015

This paper proposes a method to establish a morphological classification of Tenerife's cinder cones on the basis of a dual analysis of qualitative (existence, geometry and disposition of craters) and quantitative morphometric parameters (major and minor diameters and cone elongation, major and minor diameters and crater elongation). The result obtained is a morphological classification of the cinder cones of Tenerife, which can be sub-divided into four types: ring-shaped-cones, horseshoe-shaped-volcanoes, multiple volcanoes and volcanoes without crater. In Tenerife there is a clear dominance of horseshoe-shaped volcanoes (69.0%) over ring-shaped cones (13.1%), volcanoes without craters (11.4%) and multiple volcanoes (6.4%). The classification presented in this paper is characterized by its simplicity which makes it possible to include all morphological types of volcanoes found in Tenerife. This fact also renders our classification a useful tool to apply in other, both insular and continental volcanic areas to eventually analyze and systematize the study of eruptive edifices with similar traits. © 2014 Elsevier B.V.


D'Orazio G.,University of La Laguna | D'Orazio G.,National Research Council Italy | Asensio-Ramos M.,University of La Laguna | Asensio-Ramos M.,Instituto Volcanologico Of Canarias Involcan | And 3 more authors.
Electrophoresis | Year: 2015

In this work, the suitability of a methodology based on dispersive liquid-liquid microextraction (DLLME) has been evaluated for the extraction of four endoestrogens (estriol, 17α-estradiol, 17β-estradiol, and estrone), an exoestrogen (17α-etynylestradiol), and a mycotoxin (zearalenone), together with some of their major metabolites (2-methoxyestradiol, α-zearalanol, β-zearalanol, α-zearalenol, and β-zearalenol) from different types of milk (whole and skimmed cow milk and semiskimmed goat milk) and whole natural yogurt. The methodology includes a previous protein precipitation with acidified ACN and a defatting step with n-hexane. Separation of the analytes, determination, and quantification were developed by MEKC coupled to ESI-MS using a BGE containing an aqueous solution of ammonium perfluorooctanoate as MS friendly surfactant. Calibration, precision, and accuracy studies of the described DLLME-MEKC-MS/MS method were evaluated obtaining a good linearity and LODs in the low micrograms per liter range. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Socas-Rodriguez B.,University of La Laguna | Hernandez-Borges J.,University of La Laguna | Asensio-Ramos M.,Instituto Volcanologico Of Canarias Involcan | Herrera-Herrera A.V.,University of La Laguna | And 2 more authors.
Electrophoresis | Year: 2014

In this work, the potential of a symmetric dialkyl-substituted ionic liquid (IL), 1,3-dipenthylimidazolium hexafluorophosphate ([PPIm][PF6]), as extraction solvent in dispersive liquid-liquid microextraction (DLLME) has been studied for the analysis of a group of three natural (estriol, 17β-estradiol, and 17α-estradiol) and four synthetic (17α-ethynylestradiol, diethylstibestrol, dienestrol, and hexestrol) estrogenic compounds as well as one mycotoxin with estrogenic activity (zearalenone) in different types of water samples (Milli-Q, mineral, and wastewater). Separation, determination, and quantification were developed by HPLC-DAD and a fluorescence detector (FD) connected in series. Factors influencing the IL-DLLME procedure (sample pH, amount of IL, type and volume of disperser solvent, ionic strength, and assistance of vortex agitation) were investigated and optimized by means of a step-by-step approach. Once the optimum extraction conditions were established (10 mL of water at pH 8, 60 mg of [PPIm][PF6], 500 μL of ACN as disperser solvent and vortex agitation for 1 min), the calibration curves of the whole method (IL-DLLME-HPLC-DAD/FD) were obtained and precision and accuracy were evaluated. It was demonstrated that the developed methodology was repeatable, accurate, and selective with limits of detection in the 0.30-0.57 μg/L and 13.8-37.1 μg/L range for FD and DAD, respectively. Relative recovery values were higher than 85% for the different types of water samples and the Student's t test demonstrated that there were not significant differences between the added and the found concentration. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


PubMed | University of La Laguna and Instituto Volcanologico Of Canarias Involcan
Type: | Journal: Journal of chromatography. A | Year: 2014

Carbon nanotubes (CNTs) are still awakening scientists interest because of their inherent properties as well as their applications in a wide variety of fields. Regarding Analytical Chemistry, and although they have also been used as stationary phases in chromatography or pseudostationary phases in capillary electrophoresis, they have also found a particular place in sorbent-based extraction techniques. In fact, they are currently used as sorbents in solid-phase extraction, solid-phase microextraction, stir-bar sorptive extraction and matrix solid-phase dispersion, for analyte enrichment or storage, sample fractionation or clean-up as well as support for derivatization reactions. CNT surface is tuneable and, as a result, they can be suitably functionalized, aggregated or linked to other supports which increase their potential use as sorbents. They can also be arranged under different formats (cartridges, fibers, stir bars, disks, etc.) or even combined with magnetic nanoparticles, which clearly enlarge their applications. This review article overviews the most recent applications of CNTs as sorbent materials, covering the period from 2010 to early 2014.


PubMed | University of La Laguna, CNR Methodological Chemistry Institute and Instituto Volcanologico Of Canarias Involcan
Type: Journal Article | Journal: Electrophoresis | Year: 2016

Nano-LC and CEC were coupled to MS through a nanospray or a pressurized liquid-junction interface for the simultaneous separation and determination of 11 estrogenic compounds. Different stationary phases, that is, phenyl, C18, and C18 bidentate silica hydrate, were studied. For both techniques, the phenyl stationary phase was the best option, considering separation efficiency, selectivity, and resolution. Under the optimized conditions, the baseline separation of the target compounds (including estradiol and zearalanol epimers) was achieved in less than 20 min in nano-LC-MS and less than 13 min in CEC-MS. Molecular imprinted polymer SPE was used for extracting the target compounds from mineral water samples with the analysis of nano-LC-MS. The whole molecular imprinted polymer SPE nano-LC-MS method was validated through a recovery study at two levels of concentration. Sensitivity was improved by on-column focusing technique obtaining LODs in the range 1.4-55.4 ng/L.


Padilla G.D.,Environmental Research Division | Hernandez P.A.,Instituto Volcanologico Of Canarias Involcan | Padron E.,Instituto Volcanologico Of Canarias Involcan | Barrancos J.,Instituto Volcanologico Of Canarias Involcan | And 7 more authors.
Geochemistry, Geophysics, Geosystems | Year: 2013

Soil gas Radon (222Rn) and Thoron (220Rn) activities have been continuously measured during the period of the recent volcanic unrest that occurred at El Hierro, Canary Islands, at two different monitoring stations, namely HIE02 and HIE03. Significant increases in soil 222Rn activity and 222Rn/220Rn ratio from the soil were observed at both stations prior to the 2011-2012 submarine eruption off the coast of El Hierro, showing the highest increases before the eruption onset and before the occurrence of the strongest seismic event (M = 4.6). Statistical analysis showed that the long-term temporal trend of filtered radon data matched closely that of seismic energy release during the volcanic unrest. The observed increases of 222Rn are related to the rock fracturing processes (seismic activity) and the magmatic CO2 outflow increase, as observed in HIE03 station. Key Points Increases in soil Rn activity were observed before the submarine eruption onset © 2013 American Geophysical Union. All Rights Reserved.


Chester D.,Liverpool Hope University | Chester D.,University of Liverpool | Duncan A.,University of Liverpool | Kilburn C.,University College London | And 3 more authors.
Journal of Volcanology and Geothermal Research | Year: 2015

Cultural and political contexts are important in determining the ways in which communities respond to volcanic eruptions. Understanding the manner in which communities and the State apparatus have coped with historic eruptions can provide insights into how responses have influenced vulnerability and resilience. The 1906 eruption of Vesuvius is well suited for such a study as it was one of the first major eruptions in which there was a significant element of State control, and this worked alongside more traditional pre-industrial responses. This eruption was extensively reported in the regional, national and international press and in archives which include still photography. One feature is the rich archive of material published in English language newspapers of record which are analysed fully in the paper for the first time. Many of these data sources are now accessible on-line. The eruption started on April 4th with mild explosive activity and the eruption of lava from 5th to 7th April. On the night of the 7th/8th, activity intensified when a vigorous lava fountain inclined obliquely to the north east, deposited a thick layer of tephra on the towns of Ottaviano and San Giuseppe. This led to roof collapse and a large number of fatalities. There was increased lava emission and a flow progressed south through the outskirts of Boscotrecase cutting the Circumvesuviana railway line and almost reaching Torre Annunziata. Following April 8th the eruption declined and ended on April 21st. In the initial responses to the eruption pre-industrial features were prominent, with the local communities showing social cohesion, self-reliance and little panic. A more negative aspect was the traditional religious response that involved the use of liturgies of divine appeasement and which included the use of saintly relics and images. There is interesting evidence, however, that this coping strategy was driven by the populace rather than by the clergy. The inhabitants of San Giuseppe, for instance, insisted in taking refuge in a church and this led to over 100 fatalities when the roof collapsed. Intervention by the State included: the effective deployment of troops to handle evacuation, to re-open lines of communication and to distribute food and other relief. Management of the disaster was enhanced when prefectural commissioners were given executive powers. We argue that increased State intervention appears to have reduced self-reliance. In the short-term recovery was supported by regional/state aid and by charitable donations particularly from other governments and members of Neapolitan diaspora in other parts of Italy and abroad. This enabled land clearance, agriculture was re-established and roads/rail links were restored. Long-term recovery was slow with affected local-authorities (i.e., comuni) showing low rates of population growth for more than 15. years. © 2015 Elsevier B.V.

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