The composition of the gases released by El Chichón (Chiapas, Mexico) and Víti (Askja volcano, Iceland) volcanic lakes is examined by Multi-GAS for the first time. Our results demonstrate that H2S and SO2 are degassed by these pH 2–3 lakes. We find higher CO2/H2S and H2/H2S ratios in the lakes' emissions (31–5,685 and 0.6–35, respectively) than in the fumarolic gases feeding the lakes (13–33 and 0.08–0.5, respectively), evidencing that only a fraction (0.2–5.4% at El Chichón) of the H2S(g) contributed by the subaquatic fumaroles ultimately reaches the atmosphere. At El Chichón, we estimate a H2S output from the crater lake of 0.02–0.06 t/day. Curiously, SO2 is also detected at trace levels in the gases released from both lakes (0.003–0.3 ppmv). We propose that H2S supplied into the lakes initiates a series of complex oxidation reactions, having sulfite as an intermediate product, and ultimately leading to SO2 production and degassing.
|Numero di pagine||10|
|Rivista||Geophysical Research Letters|
|Stato di pubblicazione||Published - 2018|
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)
Aiuppa, A., Hasselle, N., Pfeffer, M., Giudice, Rouwet, Campion, R., Jácome-Paz, Bitetto, M., Bergsson, B., Aiuppa, & Taran (2018). Sulfur Degassing From Steam-Heated Crater Lakes: El Chichón (Chiapas, Mexico) and Víti (Iceland). Geophysical Research Letters, 45, 7504-7513.