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| Titel |
Continuous in-situ measurements of volcanic gases at Pisciarelli-Phelgrean Field (Italy): a new experimental approach |
| VerfasserIn |
T. Wiersberg, R. Somma, A. Rocco, F. Quattrocchi, M. Zimmer, G. De Natale, P. De Natale, E. Boschi |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025111
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| Zusammenfassung |
| We present a new experimental approach for continuous real-time monitoring of
volcanic gases. The realization of this new set-up based on the experience derived
from several earlier short-time gas monitoring campaigns carried out in 2006, 2007
and 2008 at different sites (Tor Caldara, Latium Region, Central Italy; Solfatara
and Pisciarelli, Campania Region, Souther Italy). The monitoring station is now
implemented at a fumarole field in Pisciarelli, about 1 km SE of the Solfatara volcano.
Fumarolic gas is continuously pumped through 200m Teflon © tube with a membrane
pump (pumping rate 400cc/min) into a small field laboratory, where the gas phase is
analyzed minutely by means of a quadrupole mass spectrometer for H2, H2S, CH4,
N2, O2, Ar, He, and CO2 and with a tuneable diode laser spectrometer. Further
analytical devices may be added in the future. Off-line gas samples are taken regularly
to crosscheck the gas composition with a gas chromatograph and for noble gas
analysis. Prior to gas analysis, gaseous water is condensed in a water trap placed in a
cooling box in close vicinity to the fumarole. The water is removed from the trap in
regular intervals (2 h) by a peristaltic pump. The amount of water is determined
directly in the trap by measuring the rise of the water level in intervals of 5 minutes.
Knowledge of the gas flow and the amount of water would enables us to determine the
gas/water ratio of fumarolic gases, however, the actual fumarole temperature (December
2008) at Pisciarelli is 95.8°C, thus water condensation has already occurred prior to
gas sampling. The gas from the Pisciarelli fumarole is dominated by CO2 (>98.5
vol.-%), followed by N2, H2S, O2, H2, Ar, CH4 and He. O2 and partly N2 and Ar
are due to atmospheric contamination of the system. The air-free calculated gas
composition is in good agreement with already published gas composition data. Within the
time of investigation, no significant variations were detected in the composition
of the fumarolic gases in any of the surveys performed between 2006 and 2008. |
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