Volcanogenic Halocarbons

Previous investigations reported on the volcanic production of halocarbons including chlorofluorocarbons (CFCs). It has been suggested that this natural source could account for a significant atmospheric CFC background concentration, but no quantitative assessment of its source strength has yet been...

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Bibliographic Details
Published in:Environmental science & technology 2000-03, Vol.34 (6), p.1122-1124
Main Authors: Jordan, Armin, Harnisch, Jochen, Borchers, Reinhard, Le Guern, Francois, Shinohara, Hiroshi
Format: Article
Language:English
Subjects:
AIR POLLUTION
Applied sciences
Atmospheric pollution
Chlorofluorocarbons
Dispersed sources and other
EMISSION
Emissions
ENVIRONMENTAL IMPACTS
Environmental monitoring
ENVIRONMENTAL SCIENCES
Exact sciences and technology
ORGANIC HALOGEN COMPOUNDS
Pollution
POLLUTION SOURCES
Pollution sources. Measurement results
VOLCANIC GASES
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Summary:Previous investigations reported on the volcanic production of halocarbons including chlorofluorocarbons (CFCs). It has been suggested that this natural source could account for a significant atmospheric CFC background concentration, but no quantitative assessment of its source strength has yet been presented. The synthetic mechanism for their volcanic formation has neither been clarified. Fumarole and lava gas samples from four volcanoes (Kuju, Satsuma Iwojima, Mt. Etna, Vulcano) have been studied using gas chromatography/ion trap−mass spectrometry. More than 300 organic substances were detected, among which 5 fluorinated, 100 chlorinated, 25 brominated, and 4 iodinated compounds have been identified. The most abundant organohalogen species were chlorinated methanes, unsaturated C2-chlorohydrocarbons, and chlorobenzene, suggesting a synthetic course that includes the thermolytic formation of acetylene from hydrothermal methane, condensation reactions, and synchronous catalytic halogenation in the presence of highly activated surfaces of cooling magma or juvenile ash. The only CFC compound found was CFCl3 (CFC-11), which was detected in some samples at concentrations of up to 1 ppbv. A conservative estimate of the upper limit of global CFC emissions by volcanoes clearly shows that this source is negligible as compared to the atmospheric burden by anthropogenic activities.
ISSN:0013-936X
1520-5851
DOI:10.1021/es990838q