| الملخص: | Volcanoes constitute an important source of aerosol. Here we report the size-resolved compositions of major water-soluble ions in particles collected in near-source emissions from three contrasting volcanoes (Solfatara, Vulcano and Stromboli, in Italy). Concentrations of soluble SO 42-, Cl -, F -, NO 3-, H +, K +, Na +, NH 4+, Ca 2+ and Mg 2+ were determined in 11 particle size bins from 0.069 to >25.5 μm in diameter. Soluble ions were most concentrated in the emissions from Solfatara and Stromboli. At Solfatara the major ions were NH 4+ and Cl -, tightly correlated in ∼0.8-1.5 μm diameter particles, strongly suggesting speciation as NH 4Cl. At Stromboli enhanced levels of SO 42-, H +, Na +, K + and NH 4+ were present in ∼0.5-1.5 μm diameter particles. Near-source soluble sulphate was observed in the plumes from Stromboli and Vulcano, with that from Stromboli in much higher concentration (0.94-2.14 compared with 0.07-0.13 μmol m -3). Comparing SO 42- measurements from Vulcano to those from other volcanic systems suggests that near-source sulphate aerosol emissions scale with SO 2 and contribute ∼0.03-0.05 Tg yr -1 of sulphur to the atmosphere. Simple calculations suggest that all the particles containing these soluble ions will act as cloud condensation nuclei at typical atmospheric supersaturations. © 2004 Elsevier Ltd. All rights reserved.
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