Emisiones de bióxido de azufre del volcán Popocatépetl, México durante la erupción de diciembre 1994- enero 1995

Se presenta un análisis de las mediciones de flujo de bióxido de azufre proveniente del volcán Popocatépetl durante febrero de 1994-enero 1995. Los métodos utilizados y las incertidumbres en las mediciones son descritos objetivamente. Los resultados indican que las emisiones máximas de gas (SO2) y posiblemente de partículas (cenizas)ocurrieron 72 horas después de iniciado el proceso eruptivo, alcanzando valores máximos del tremor y del número de eventos tipo B de acuerdo a los reportes de sismología presentados independientemente. Se puede considerar que la línea base de emisión de SO2 durante el periodo mencionado es de 1,000 toneladas/día. Finalmente, se recomienda determinar regularmente al bióxido de azufre junto con la sismicidad y la deformación de volcanes activos para la mejor estimación del peligro volcánico (AU)

Sulphur eruptions at volcán Poás, Costa Rica

Since the recent desiccation of the crater lake at Volcán Poás, Costa Rica, vigorous fumarolic activity on the exposed lake bed has been associated with the manifestation of miniature sulphur flows and sulphur pools. In this paper, observations of 2-3 m high, active sulphur volcanoes are reported, and mechanisms for their formation proposed and discussed. Their ejecta, composed of milled particles, crystals and accretionary lapilli of sulphur, are unlike previously described pyroclastic sulphur deposits, and probably form from a spray of crystallised sulphur forced to the surface by fumarolic gases passing upwards through shallow bodies of liquid sulphur. While much of the erupted material is recycled, the reservoir of molten sulphur can also be replenished by influxing magmatic - hydrothermal fluids. The greenish colouration of the sulphur, reminiscent of other documented terrestrial sulphur eruptions, is probably due to impurities. This emphasises the point that interpretation of spectral reflectances of the jovian moon Io, regarding the posible contribution of sulphur, cannot rely on extrapolation of laboratory data for pure materials (AU)

The sulphur cycle

impact of sulphur from fossil fuel combustion on the environment is well recognised. This is particularly so in Europe, North America and other regions of high fossil fuel consumption. On the other hand the role of sulphur gases, especially dimenthyl sulphide (DMS), produced be marine phytoplankton on environmental processes is less well established (AU)