Carbon dioxide: allied with karst
Among the substances that can increase the corrosive power of natural water, carbon dioxide (CO2) has the most important role. It is already present in meteoric waters, as it is one of the gases of the atmosphere, however its percentages are very low (0.03 atm). Its concentration increases greatly in waters that cross through thick layers of soil covered with dense vegetation. Enrichment with CO2 and other organic acids produced by vegetation and biological activity of water coming into contact with rock can lead to a remarkable increase in the solubility of minerals like calcite (calcium carbonate, CaCO3) and dolomite (calcium carbonate and magnesium, CaMg(CO3)2), which increases from 10-12 mg/l to 200-400 mg/l. Other minerals, such as quartz or rock salt are on the contrary insensitive to the presence of CO2 in the water they come into contact with, and their solubility therefore remains unchanged.
The dissolution reaction of calcium carbonate responsible for the formation of most caves is: CaCO3 + CO2 + H2O = Ca2+ + 2HCO3– In the case of dolomite, the reaction is very similar : CaMg(CO3)2 + 2CO2 + 2H2O = Ca2+ + Mg2+ + 4HCO3–
Special reports
-
11 June 2012
Bats, facts and fiction
In ancient Rome, bats were nailed to the door of the house as a protection from witches...
16 April 2012
Bats, The Lords of Darkness
The UNEP Convention on Migratory Species and The Agreement on the Conservation of...
-
13 May 2013
Small steps, great footprints
Have you ever wondered how much space is taken up by an apple or a steak?...
-
28 August 2020
The Earth seen from above: signs of fires
This image was taken by the ASTER sensor installed on the NASA TERRA satellite platform. The image was taken on…
15 July 2020
Earth viewed from above
Remote satellite sensing: what it is and what it is used for In the scientific field, the images produced by…
30 April 2019
Urban woods
When walking along a tree-lined avenue in a crowded and traffic-congested city, wrapped up in our daily commitments, we do…
-
11 June 2012
Bats, facts and fiction
In ancient Rome, bats were nailed to the door of the house as a protection from witches...
16 April 2012
Bats, The Lords of Darkness
The UNEP Convention on Migratory Species and The Agreement on the Conservation of...
-
13 May 2013
Small steps, great footprints
Have you ever wondered how much space is taken up by an apple or a steak?...
-
11 June 2012
Bats, facts and fiction
In ancient Rome, bats were nailed to the door of the house as a protection from witches...
-
16 April 2012
Bats, The Lords of Darkness
The UNEP Convention on Migratory Species and The Agreement on the Conservation of...
From the Multimedia section
Facts
-
Can you breathe in a cave?
One of the most common beliefs is that in caves the air is often stuffy...
-
And in underground tunnels?
There are groups of terrestrial animals that eat insects, worms and other invertebrates...
The climate underground
Going down deep in the Earth’s crust, the temperatures increase gradually...
-
A small domestic experiment
In order to understand the number of factors that make a water undersaturated or...
-
13 May 2011
Ice in caves
In high mountain or high latitude environments, many caves can contain ice deposits...
-
Can you breathe in a cave?
One of the most common beliefs is that in caves the air is often stuffy...
-
24 February 2011
And in underground tunnels?
There are groups of terrestrial animals that eat insects, worms and other invertebrates...
13 May 2011
The climate underground
Going down deep in the Earth’s crust, the temperatures increase gradually...
-
Can you breathe in a cave?
One of the most common beliefs is that in caves the air is often stuffy...