0000000000189730
AUTHOR
Gilbert Hammouya
Mercury gas emissions from La Soufrière Volcano, Guadeloupe Island (Lesser Antilles)
Abstract Quantifying mercury (Hg) emissions from active volcanoes is of particular interest for better constraining the global cycle and environmental impact of this highly toxic element. Here we report on the abundance of total gaseous (TGM = Hg 0 (g) + Hg II (g) ) and particulate (Hg (p) ) mercury in the summit gas emissions of La Soufriere andesitic volcano (Guadeloupe island, Lesser Antilles), where enhanced degassing of mixed hydrothermal-magmatic volatiles has been occurring since 1992 from the Southern summit crater. We demonstrate that Hg in volcanic plume occurs predominantly as gaseous mercury, with a mean TGM/Hg (p) mass ratio of ~ 63. Combining the mean TGM/H 2 S mass ratio of …
Steam and gas emission rate from La Soufriere volcano, Guadeloupe (Lesser Antilles): Implications for the magmatic supply during degassing unrest
Abstract Since its last magmatic eruption in 1530 AD, La Soufriere andesitic volcano in Guadeloupe has displayed intense hydrothermal activity and six phreatic eruptive crises. Here we report on the first direct quantification of gas plume emissions from its summit vents, which gradually intensified during the past 20 years. Gas fluxes were determined in March 2006 and March 2012 by measuring the horizontal and vertical distributions of volcanic gas concentrations in the air-diluted plume and scaling to the speed of plume transport. Fluxes in 2006 combine real-time measurements of volcanic H2S concentrations and plume parameters with the composition of the hot (108.5 °C) fumarolic fluid at …
Pre- and syn-eruptive geochemistry of volcanic gases from Soufriere Hills of Montserrat, West Indies
International audience; Soufriere Hills fumaroles contained magmaderived volatiles before and during the eruption initiated in 1995 but also preserved a typical and quite steady hydrothermal coinposition. Chemical changes due to increased boiling and a greater input of oxidizing magmatic gas occurred only at Galway's Soufriere, the most active fumarolic field. Hydrothermal buffering of the fumaroles has been favoured by their remote location (!-2 km) froin the eruptive vents and by a preferential degassing of the uprising magma through intrusive conduits under the crater. High temperature (720øC) gas collected froin the extruding lava dome in Feb. 1996 was chemically and isotopically repres…