The airborne lava-seawater interaction plume at Kilauea Volcano, Hawai'i

Lava flows into the sea at Kilauea Volcano, Hawai'i, and generates an airborne gas and aerosol plume. Water (H2O), hydrogen chloride (HCl), carbon dioxide (CO2) nitrogen dioxide (NO2) and sulphur dioxide (SO2) gases were quantified in the plume in 2004-2005, using Open Path Fourier Transform infra-red Spectroscopy. The molar abundances of these species and thermodynamic modelling are used to discuss their generation. The range in molar HCl/H2O confirms that HCl is generated when seawater is boiled dry and magnesium salts are hydrolysed (as proposed by [T.M. Gerlach, J.L. Krumhansl, R.O. Fournier, J. Kjargaard, Acid rain from the hearing and evaporation of seawater by molten lava: a new volcanic hazard, EOS (Trans. Am. Geophys. Un.) 70 (1989) 1421-1422]), in contrast to models of Na-metasomatism. Airborne droplets of boiled seawater brine form nucleii for subsequent H,O-2 and HCl condensation, which acidifies the droplets and liberates CO2 gas from bicarbonate and carbonate. NO, is derived from the thermal decomposition of nitrates in coastal seawater, which takes place as the lava heats droplets of boiled seawater brine to 350-400 degrees C. SO2 is derived from the degassing of subaerial lava flows on the coastal plain. The calculated mass flux of HCl from a moderate-sized ocean entry significantly increases the total HCl emission at Kilauea (including magmatic sources) and is comparable to industrial HCl emitters in the United States. For larger lava ocean entries, the flux of HC1 will cause intense local environmental hazards, such as high localised HCl concentrations and acid rain. (c) 2006 Elsevier B.V. All rights reserved.