UIS Commission on Karst Hydrogeology and Speleogenesis

Viepoints and comments

  PDF: /pdf/seka_pdf4497.pdf

Condensation corrosion is a little studied, but important dissolutional process that occurs within caves in many karst settings around the world (for a review see Dublyansky and Dublyansky, 2000). Condensation corrosion occurs when air equilibrates with the cave atmosphere, becomes acidic and dissolves the bedrock and speleothems. It is a later vadose process that apparently depends on air circulation patterns, number of entrances and general configuration (vertical range, presence of ponded water, passage shape, etc) of the cave. Both bedrock and speleothems can be affected by the process, resulting in weathered outer surfaces. Condensation corrosion in speleogenesis has been regarded as responsible for dissolutional modification during later stages of cave development of coastal (Tarhule-Lips and Ford, 1998) and hypogenic caves (Hill, 1987; Palmer and Palmer, 2000).

  PDF: /pdf/seka_pdf4478.pdf

(Comments to Wolfgang Dreybrodt remark "On feasibility of condensation processes in caves", Speleogenesis and Evolution of Karst Aquifers, 1 (2), 2003, www.speleogenesis.info)

Audra, Bigot and Mocochain (2003) proposed an explanation for the development of a hydrothermal cave in Provence (France), referring to the Szunyogh model (1989). Dreybrodt (2003) then shows by calculations that this model is unlikely. We will discuss Dreybrodt’s answer here. Our conclusions will emphasise that Dreybrodt’s hypothesis (transient conduction in a semi-infinite solid) is not the only possibility. When other conditions are considered (steady-state conduction with constant temperature at a finite distance), this cupola-development model can be valid.

  PDF: /pdf/seka_pdf4497.pdf

Auler A.S. and Smart P.L.

Abstract: Condensation corrosion is a little studied, but important dissolutional process that occurs within caves in many karst settings around the world (for a review see Dublyansky and Dublyansky, 2000). Condensation corrosion occurs when air equilibrates with the cave atmosphere, becomes acidic and dissolves the bedrock and speleothems. It is a later vadose process that apparently depends on air circulation patterns, number of entrances and general configuration (vertical range, presence of ponded water, passage shape, etc) of the cave. Both bedrock and speleothems can be affected by the process, resulting in weathered outer surfaces. Condensation corrosion in speleogenesis has been regarded as responsible for dissolutional modification during later stages of cave development of coastal (Tarhule-Lips and Ford, 1998) and hypogenic caves (Hill, 1987; Palmer and Palmer, 2000).

  PDF: /pdf/seka_pdf4468.pdf

Abstract:

In Fig. 6 of this paper the authors suggest how condensation corrosion could shape ceiling cupolas. Hot water containing high concentration of carbon dioxide rises to a lake filling the lower part of the cave room. Degassing of CO2 creates a CO2-containing atmosphere, which is heated by the warmer water below and becomes saturated with vapor, which condenses to the cooler wall of the cave, dissolves limestone and flows back to the lake.

If this process would continue in time it would be perfect to shape large cupolas. However, it does not because condensation stops when the temperature of the cave walls approaches that of the heated air. The reason is that condensation of water at the cave wall releases heat of condensation of 2.45 kJoule/g. This corresponds to an energy flux of 28 Watt/square-meter if a film of 1 mm depth would condensate to the wall in one day. In addition there is also a flux of heat from the warm air to the cave wall. Since the thermal conductivity of limestone (1.3 Watt/m°K) and its thermal diffusivity (5.6 x 10-7 m2/s) are low this heat cannot be rapidly transported into the bedrock, and consequently the temperature of the cave wall rises. Therefore the amount of condensation is reduced. 

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Baudouin Lismonde

Limestone wall retreat in a ceiling cupola controlled by hydrothermal degassing with wall condensation ( Szunyogh model) ( Comments to Wolfgang Dreybrodt remark "On feasibility of condensation processes in caves", Speleogenesis and Evolution of Karst Aquifers, 1 (2), 2003, www.speleogenesis.net )

Audra, Bigot and Mocochain (2003) proposed an explanation for the development of a hydrothermal cave in Provence ( France ), referring to the Szunyogh model (1989). Dreybrodt (2003) then shows by calculations that this model is unlikely. We will discuss Dreybrodt's answer here. Our conclusions will emphasise that Dreybrodt's hypothesis (transient conduction in a semi-infinite solid) is not the only possibility. When other conditions are considered (steady-state conduction with constant temperature at a finite distance), this cupola-development model can be valid.