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| Titel |
The natural flux of greenhouse gases in the case of monitoring the flux of juvenile carbon dioxide in the Hranice Karst |
| VerfasserIn |
Milan Geršl, Uroš Stepišnik, Jan Mareček, Eva Gerslova, Michal Hammerschmiedt |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105116
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| Publikation (Nr.) |
 EGU/EGU2015-4565.pdf |
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| Zusammenfassung |
| Located in the Teplice nad BeÄvou district 40 km SE of Olomouc (Czech Republic), the
hydrothermal Hranice Karst with the Zbrašov Aragonite Caves has been developed in the
sequence of Palaeozoic limestones as a result of deep influx of thermal water charged
with subcrustal carbon dioxide (CO2). This area of discharge of juvenile carbon
dioxide is a unique place where one can study the long-term natural production of a
greenhouse gas and confront it with the anthropogenic production. As a result, the
continuous measurements of the properties of the cave microclimate with additional
seasonal measurements of flux of carbon dioxide give rise to a rare pool of data that
cover natural routes of greenhouse gases. Repeated seasonal analysis of the ratio
of stable carbon isotopes in carbon dioxide (d13C around -5 ) (Meyberg – Rinne,
1995)has suggested the juvenile (mantle) origin of this gas. Isotopic analyses in the
mineral water of dissolved gases (He) show that some part of these gases come
from the upper mantle of the Earth. The lower floors of the caves are filled with
carbon dioxide producing so-called gas lakes in the area. Concentrations of the gas
commonly reach 40 % by volume. In 1999, for example, the average concentration in the
Gallas dome was 84.9 % by volume. Flux of CO2 (g.m-2.d-1) was measured on the
surface and in the cave. The homogenisation chamber and the pumping test were
applied to evaluate the CO2 flux. The average CO2 flux in the soil ranged from 74
to 125 g.m-2.d-1, reflecting the venting of subcrustal CO2 in the Hranice area
(Geršl et al., 2012). In the Zbrašov Aragonite Caves the CO2 concentration in the
atmosphere fluctuates from 0,X to 85 % with the measured constant flux being 32 894
g.m-2.d-1. Since 2005, the CO2 concentrations in the cave area have been reported by an
automatic monitoring system at 10 cave sites. CO2 concentrations are recorded in 5-min
intervals. Interpretation can be put into the context of measuring concentrations
of Rn, groundwater levels, and influence of the ambient conditions on the cave
system and the operation of the visitor trail. The data obtained are an exceptional
source of information about the behaviour of natural emissions of a greenhouse
gas in the form of juvenile carbon dioxide. The hydrothermal speleothems carry
unique information about production of carbon dioxide in the studied area. Based
on their dating using the 230Th/234U method it can be deduced indirectly that the
carbon dioxide emissions occurred as early as 84-127 thousand years ago in the
area.
The research was conducted with the support of the project entitled "Postdoc contracts at
MENDELU technical and ekonomical research” (CZ.1.07/2.3.00/30.0031).
Geršl, M. – Geršlová, E. – ŠimeÄková, B. (2012): Subcrustal CO2 flux measurement in
the Hranice hydrothermal Karst, methodology and first results. – Geoscience research reports
for 2011, 45, D, 162-166. Praha.
Meyberg, M. – Rinne, B. (1995): Messung des 3He/4He-Isotopenverhältnisses im
Hranicka Propast (Tschechische Republik). – Die Höhle. Zeitschrift für Karst- und
Höhlenkunde, 46, 1, 5-8. Wien. |
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