In:
Geochemistry, Geophysics, Geosystems, American Geophysical Union (AGU), Vol. 7, No. 5 ( 2006-05)
Abstract:
In order to assess the contribution of quiescent degassing volcanoes to the global halo(hydro)carbon inventory, we have quantified volcanic fluxes of methyl halides (CH 3 Cl, CH 3 Br, and CH 3 I), ethyl halides (C 2 H 5 Cl, C 2 H 5 Br, and C 2 H 5 I), and higher chlorinated methanes (CH 2 Cl 2 , CHCl 3 , and CCl 4 ). About every eight months over a 2‐year period (July 2001 to July 2003), gas samples were collected and analyzed from high‐temperature fumaroles (472°C–776°C) at the Nicaraguan subduction zone volcano Momotombo. Using a simultaneous record of trace and main compounds in fumarolic gases as well as SO 2 fluxes of the plume, we were able to calculate halo(hydro)carbon fluxes for Momotombo and extrapolate our results to estimate halo(hydro)carbon fluxes for the whole Quaternary Nicaraguan volcanic arc and, in addition, for all volcanoes globally. The most abundant halohydrocarbon was CH 3 Cl with concentrations up to 19 ppmv. Further major halo(hydro)carbons were CH 3 Br, CH 3 I, CH 2 Cl 2 , CHCl 3 , CCl 4 , C 2 H 5 Cl, C 2 H 5 Br, C 2 H 5 I, and C 2 H 3 Cl with an average concentration of 0.20 to 720 ppbv. Estimated mean halo(hydro)carbon fluxes from Momotombo were in the range of 630–5000 g/yr for methyl halides, 49–260 g/yr for ethyl halides, and 2.4–24 g/yr for higher chlorinated methanes. When the results for Momotombo are scaled up to SO 2 fluxes of the Nicaraguan volcanic transect, fluxes of 1.7 × 10 5 g/yr CH 3 Cl and 82 g/yr CCl 4 are attained for Nicaragua. Scaled up to the estimated global SO 2 flux, this translates to hypothetical global fluxes of 5.6 × 10 6 g/yr CH 3 Cl and 2.7 × 10 3 g/yr CCl 4 . These volcanic fluxes are negligible compared to global anthropogenic and natural emissions of about 3 × 10 12 g/yr CH 3 Cl and 2 × 10 10 g/yr CCl 4 .
Type of Medium:
Online Resource
ISSN:
1525-2027
,
1525-2027
DOI:
10.1029/2005GC001162
Language:
English
Publisher:
American Geophysical Union (AGU)
Publication Date:
2006
detail.hit.zdb_id:
2027201-7
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