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| Titel |
Diffusive emissions of hydrothermal methane and higher hydrocarbons from the soil at Nisyros (Greece) |
| VerfasserIn |
Walter D'Alessandro, Jacopo Cabassi, Sergio Calabrese, Francesco Capecchiacci, Kyriaki Daskalopoulou, Jens Fiebig, Antonina Lisa Gagliano, Artemis Kontomichalou, Konstantinos Kyriakopoulos, Silvia Milazzo, Franco Tassi |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091884
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| Publikation (Nr.) |
 EGU/EGU2014-6198.pdf |
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| Zusammenfassung |
| Methane plays an important role in the Earth’s atmospheric chemistry and radiative balance
being the second most important greenhouse gas after carbon dioxide. Methane is released to
the atmosphere by a wide number of sources, both natural and anthropogenic, with the latter
being twice as large as the former. It has recently been established that significant amounts of
geological methane and higher hydrocarbons, produced within the Earth’s crust, are currently
released naturally into the atmosphere. Active or recent volcanic/geothermal areas represent
one of these sources of geological methane and higher hydrocarbons. Here we report on soil
gas flux measurements made at Nisyros a currently quiescent active volcanic system
with strong fumarolic activity due to the presence of a high enthalpy geothermal
system.
Methane and CO2 flux measurements from the soils were made with the accumulation
chamber method in Lakki plain covering an area of about 0.01 km2 including the main
fumarolic areas of Kaminakia, Ramos, Stefanos, Lofos and Phlegeton. The 127
measurements range from –3.4 to 1420 mg m-2 d-1 for CH4 and from 0.1 to 383 g m-2 d-1
for CO2.
The five fumarolic areas show very different methane degassing pattern Kaminakia showing
the highest flux values. The estimated methane output of these areas range about 0.01 t/a at
Phlegeton to about 0.25 t/a at Kaminakia. The total output from the entire geothermal
system of Nisyros should not exceed 1 t/a. The results of the chemical analyses of
the concurrently collected fumarolic gases of the island gave clues on probable
methanotrophic activity within the soil. Microbial activity in the soil of Lakki plain
also controls the diffusive emission of thermogenic hydrocarbons released from
the hydrothermal reservoir, mainly consisting of alkanes, aromatics and alkenes,
which are partially transformed into their derivatives, such as aldehydes, ketons and
alcohols. |
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