Mercury and halogen emissions from Masaya and telica volcanoes, Nicaragua
Witt MLI., Mather TA., Pyle DM., Aiuppa A., Bagnato E., Tsanev VI.
We report measurements of Hg, SO2, and halogens (HCl, HBr, HI) in volcanic gases from Masaya volcano, Nicaragua, and gaseous SO2and halogens from Telica volcano, Nicaragua. Mercury measurements were made with a Lumex 915+ portable mercury vapor analyzer and gold traps, while halogens, CO2and S species were monitored with a portable multi gas sensor and filter packs. Lumex Hg concentrations in the plume were consistently above background and ranged up to 350 ng m-3. Hg/SO2mass ratios measured with the real-time instruments ranged from 1.1 × 10-7to 3.5 × 10-5(mean 2 × 10-5). Total gaseous mercury (TGM) concentrations measured by gold trap ranged from 100 to 225 ng m-3. Reactive gaseous mercury accounted for 1% of TGM, while particulate mercury was 5% of the TGM. Field measurements of Masaya's SO2flux, combined with the Hg/SO2ratio, indicate a Hg flux from Masaya of 7.2 Mg a-1. At Masaya's low temperature famaroles, Hg/CO2mass ratios were consistently around 2 × 10-8, lower than observed in the main vent (Hg/C02 ∼ 10-7). Low-temperature fumarole Hg fluxes from Masaya are insignificant (∼150 g a-1). Ratios of S, C and halogen species were also measured at Masaya and Telica volcanoes. CO2/ SO2ratios at Masaya ranged from 2.8 to 3.9, comparable to previously published values. At Masaya molar Br/SO2was 3 × 10-4and I/SO2was 2 × 10-5, suggesting fluxes of 0.2-0.5 Mg HBr d-1and 0.02-0.05 Mg HI d-1. At Telica the Br/SO2ratio was also 3 × 10-4and the I/SO2ratio was 5.8 × 10-5, with corresponding fluxes of 0.2 Mg HBr d-1and 0.06 Mg HI d-1. Gases at both volcanoes are enriched in I relative to Br and Cl, compared to gases from volcanoes elsewhere. Copyright 2008 by the American Geophysical Union.