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Delmelle, Pierre
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Delmelle, Pierre
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- PublicationRestrictedSources, size distribution and downwind grounding of aerosols from Mt. Etna(2006)
; ; ; ; ; ; ; ; ; ; ;Allen, A. G.; 1School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK. ;Mather, T. A.; Department of Earth Sciences, University of Cambridge, Cambridge, UK. ;McGonigle, A. J. S.; Department of Geography, University of Sheffield, Sheffield, UK. ;Aiuppa, A.; Dipartimento di Chimica e Fisica della Terra ed Applicazioni, University of Palermo, Palermo, Italy. ;Delmelle, P.; Environmental Health Unit, Institut Scientifique de Service Public, Lie`ge, Belgium. ;Davison, B.; Institute of Environmental and Natural Sciences, University of Lancaster, Lancaster, UK. ;Bobrowski, N.; Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany. ;Oppenheimer, C.; Department of Geography, University of Cambridge, Cambridge, UK. ;Pyle, D. M.; Department of Earth Sciences, University of Cambridge, Cambridge, UK. ;Inguaggiato, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; ; ; ; ; ; ; ;; The number concentrations and size distributions of aerosol particles >0.3 mm diameter were measured at the summit of Mount Etna and up to 10 km downwind from the degassing vents during July and August 2004. Aerosol number concentrations reached in excess of 9 106 L 1 at summit vents, compared to 4–8 104 L 1 in background air. Number concentrations of intermediate size particles were higher in emissions from the Northeast crater compared to other summit crater vents, and chemical composition measurements showed that Northeast crater aerosols contained a higher mineral cation content compared to those from Voragine or Bocca Nuova, attributed to Strombolian or gas puffing activity within the vent. Downwind from the summit the airborne plume was located using zenith sky ultraviolet spectroscopy. Simultaneous measurements indicated a coincidence of elevated ground level aerosol concentrations with overhead SO2, demonstrating rapid downward mixing of the plume onto the lower flanks of the volcano under certain meteorological conditions. At downwind sites the ground level particle number concentrations were elevated in all size fractions, notably in the 2.0–7.5 mm size range. These findings are relevant for assessing human health hazard and suggest that aerosol size distribution measurements may aid volcanic risk management.205 29 - PublicationOpen AccessAsh aggregation enhanced by deposition and redistribution of salt on the surface of volcanic ash in eruption plumes(2017-03-31)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Interactions with volcanic gases in eruption plumes produce soluble salt deposits on the surface of volcanic ash. While it has been postulated that saturation-driven precipitation of salts following the dissolution of ash surfaces by condensed acidic liquids is a primary mechanism of salt formation during an eruption, it is only recently that this mechanism has been subjected to detailed study. Here we spray water and HCl droplets into a suspension of salt-doped synthetic glass or volcanic ash particles, and produce aggregates. Deposition of acidic liquid droplets on ash particles promotes dissolution of existing salts and leaches cations from the underlying material surface. The flow of liquid, due to capillary forces, will be directed to particle-particle contact points where subsequent precipitation of salts will cement the aggregate. Our data suggest that volcanically-relevant loads of surface salts can be produced by acid condensation in eruptive settings. Several minor and trace elements mobilised by surface dissolution are biologically relevant; geographic areas with aggregation-mediated ash fallout could be "hotspots" for the post-deposition release of these elements. The role of liquids in re-distributing surface salts and cementing ash aggregates also offers further insight into the mechanisms which preserve well-structured aggregates in some ash deposits.123 44 - PublicationRestrictedBioindication of volcanic mercury (Hg) deposition around Mt. Etna (Sicily)(2012)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Mt. Etna is a major natural source of Hg to the Mediterranean region. Total mercury concentrations, [Hg]tot,in Castanea sativa (sweet chestnut) leaves sampled 7–13 km from Etna's vents (during six campaigns in 2005–2011) were determined using atomic absorption spectroscopy. [Hg]tot in C. sativa was greatest on Etna's SE flank reflecting Hg deposition from the typically overhead volcanic plume. [Hg]tot also showed Hg accumulation over the growing season, increasing with leaf age and recent eruptive activity. [Hg]tot in C. sativa was not controlled by [Hg]tot in soils, which instead was greatest on Etna's NW flank, and was correlated with the proportion of organic matter in the soil (% Org). An elevated [Hg]tot/% Org ratio in soils on Etna's SE flank is indicative of increased Hg deposition. This ratio was also found to decrease with local soil pH, suggesting that Hg deposited to the low pH and organic-poor soils on Etna's SE flank may not be retained but will instead be released to groundwater or re-emitted to the atmosphere. These results show that the deposition of volcanic Hg has clear impacts and confirm that Etna is an important source of Hg to the local environment.24 1