Characterisation and evolution of tropospheric plumes from Lascar and Villarrica volcanoes, Chile

[ 1] Direct sampling ( filter pack and impactor) and remote sensing ( ultraviolet spectroscopy and Sun photometry) of the plumes of Lascar and Villarrica volcanoes, Chile, reveal that both are significant and sustained emitters of SO2 ( 28 and 3.7 kg s(-1), respectively), HCl ( 9.6 and 1.3 kg s(-1), respectively), HF ( 4.5 and 0.3 kg s(-1), respectively) and near-source sulfate aerosol ( 0.5 and 0.1 kg s(-1), respectively). Aerosol plumes are characterized by particle number fluxes ( 0.08-4.0 mum radius) of -10(17) s(-1) ( Lascar) and -10(16) s(-1) ( Villarrica), the majority of which will act as cloud condensation nuclei at supersaturations >0.1%. Impactor studies suggest that the majority of these particles contain soluble SO2($) over bar (4). Most aerosol size distributions were bimodal with maxima at radii of 0.1-0.2 mum and 0.7-1.5 mum. The mean particle effective radius ( R-eff) ranged from 0.1 to 1.5 mum, and particle size evolution during transport appears to be controlled by particle water uptake ( Villarrica) or loss ( Lascar) rather than sulfate production.