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Le Blond, J. S.
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Le Blond, J. S.
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- PublicationRestrictedA physico-chemical assessment of the health hazard of Mt. Vesuvius volcanic ash(2010-04-01)
; ; ; ; ; ; ; ; ;Horwell, C. J.; Institute of Hazard, Risk & Resilience, Department of Earth Sciences, Durham University, Science Site, Durham, UK; Department of Earth Sciences, University of Bristol, Bristol, UK ;Stannett, G. W.; Department of Earth Sciences, University of Bristol, Bristol, UK ;Andronico, D.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Bertagnini, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Fenoglio, I.; Dipartimento di Chimica, I.F.M. and Interdipartmental Center “G. Scansetti” for the Study of Asbestos and other Toxic Particulates, Università degli studi di Torino, Torino Italy ;Fubini, B.; Dipartimento di Chimica, I.F.M. and Interdipartmental Center “G. Scansetti” for the Study of Asbestos and other Toxic Particulates, Università degli studi di Torino, Torino, Italy ;Le Blond, J. S.; Department of Mineralogy, The Natural History Museum, London, UK; Department of Geography, University of Cambridge, Downing Site, Cambridge, UK ;Williamson, B. J.; Camborne School of Mines, University of Exeter, Penryn, Cornwall, UK; ; ; ; ; ; ; Mt. Vesuvius, Italy, is regarded as one of the world's most dangerous volcanoes because of the potential for vast numbers of people to be affected by the renewal of volcanic activity; more than 600 000 people live within 10 km of the summit alone. Vesuvius has been quiescent since 1944 and with continued dormancy, the more likely it is that the next eruption will be explosive. At that point, wide-spread concern is likely over the potential health hazard of the ash, away from the zone of primary volcanic hazards. Analyses of the mineralogical and geochemical characteristics of ash provide us with critical information on the potential toxicity of the particles, for example, whether particles are sufficiently small to enter the lungs and whether the particles have reactive properties which could trigger disease. Rapid assessment of these characteristics allows real-time decision making on hazard mitigation issues (e.g. distribution of dust masks) and allows considered judgement on whether to embark on major medical/toxicological studies. The study presented here is the first time that the potential respiratory health hazard of ash from Vesuvius volcano has been considered and allows planning for future eruption scenarios. Twenty-one ash samples, representing the range of eruption styles at Vesuvius, were collected and analysed. The results demonstrate that the physical processes of fragmentation play an important role in determining the grain size and, therefore, hazard, of the ash. Here, the finest samples derive from the interaction of magma and water during the final, phreatomagmatic phases of plinian and subplinian eruptions ( 16 vol.% <4 µm material), while the low-intensity explosivity activity, associated with lava effusion, produces coarse ash posing a lesser hazard. The quantity of material found in the different health-pertinent fractions is strongly correlated, allowing prediction of these fractions where only coarser sieve data are available. Since Vesuvius produces silica under-saturated products, ‘free’ crystalline silica in the ash does not pose a significant health hazard (< 2 wt.% cristobalite and <3 wt.% quartz). Surface tests showed that the capability of the ash to generate the highly-reactive hydroxyl free radical varies considerably amongst samples, with available surface iron correlating well with reactivity potential.133 29 - PublicationRestrictedGas and aerosol emissions from Villarrica volcano, Chile(2011)
; ; ; ; ; ; ; ; ; ; ;Sawyer, G. M.; Department of Geography, University of Cambridge ;Salerno, G. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Le Blond, J. S.; Department of Geography, University of Cambridge - Department of Mineralogy, Natural History Museum ;Martin, R. S.; School of Biological and Chemical Sciences, Queen Mary, University of London - Department of Earth Sciences, University of Cambridge ;Spampinato, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia ;Roberts, T. J; Norwegian Polar Institute, Polar Environmental Centre ;Mather, T. A.; Department of Earth Sciences, University of Oxford ;Witt, M. L. I.; Department of Earth Sciences, University of Oxford ;Tsanev, V. I.; Department of Geography, University of Cambridge ;Oppenheimer, C.; Department of Geography, University of Cambridge; ; ; ; ; ; ; ; ; Here we report results from a multidisciplinary field campaign at Villarrica volcano, Chile, in March 2009. A range of direct sampling and remote sensing techniqueswas employed to assess gas and aerosol emissions from the volcano, and extend the time series of measurements that have been made during recent years. Airborne traverses beneath the plume with an ultraviolet spectrometer yielded an average SO2 flux of 3.7 kg s−1. This value is similar to previous measurements made at Villarrica during periods of quiescent activity. The composition of the plume was measured at the crater rim using electrochemical sensors and, for the first time, open-path Fourier transforminfrared spectroscopy, yielding a composition of 90.5 mol% H2O, 5.7% CO2, 2.6%SO2, 0.9% HCl, 0.3% HF and b0.01% H2S. Comparison with previous gas measurements made between 2000 and 2004 shows a correlation between increased SO2/HCl ratios and periods of increased activity. Base-treated filter packs were also employed during our campaign, yielding molar ratios of HBr/SO2=1.1×10−4, HI/SO2=1.4×10−5 and HNO3/SO2=1.1×10−3 in the gas phase. Our data represent the most comprehensive gas inventory at Villarrica to date, and the first evaluation of HBr and HI emissions from a South American volcano. Sun photometry of the plume showed the near-source aerosol size distributions were bimodal with maxima at b0.1 and ~1 μm. These findings are consistent with results from analyses in 2003. Electron microscope analysis of particulatematter collected on filters showed an abundance of sphericalmicron-sized particles that are rich in Si, Mg and Al. Non-spherical, S-rich particles were also observed.205 28