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Mexico's cultural heritage threatened by acid rain

Mexico's cultural heritage threatened by acid rain

The buildings and monuments of the Mayan culture are deteriorating as a result of acid rain,warned Pablo Sánchez, academic at the UNAM Center for Atmospheric Sciences.

What is acid rain?

Is calledacid rain to which is formed when the humidity of the air combines with nitrogen oxides, sulfur dioxide or sulfur trioxide emitted by factories, power plants, heating boilers and vehicles that burn coal or petroleum products that contain sulfur. In interaction with rainwater, these gases form nitric acid, sulfurous acid, and sulfuric acid. Finally, these chemical substances fall to the earth accompanying the precipitation, constituting acid rain.

The primary air pollutants that give rise to acid rain can travel great distances, being carried by the wind hundreds or thousands of kilometers before precipitating in the form of dew, rain, drizzle, hail, snow, fog or mist. When precipitation occurs, it can lead to deterioration in the environment.

This phenomenon is the one that is destroying the cultural heritage of the Mayan civilization, warned the biologist Pablo Sánchez.

Mexico about to lose its Mayan cultural heritage

The material with which the ancient Mayan constructions and monuments are erected contains limestone rock, the main component of which is calcium carbonate that is solubilized in acid rain, thus degrading the inscriptions and the millenary legacy.

"In a period of one hundred years all the inscriptions and writings on the stelae and columns may be lost", said the academic from the Atmospheric Sciences Center of the National Autonomous University of Mexico (UNAM).

The problem is compounded, since many of the Mayan buildings are built in the open air and, therefore, very exposed to the environment and degradation.

What the experts say

Restoration experts still cannot find a solution to protect buildings. Already "their lintels and stelae are affected" progressively because of acid rain.

The problem is that limestone rock "cannot be put on a protective layer because the rocks have to breathe, absorbing moisture and water and, if a sealing layer is put on them, what is caused is an acceleration of degradation" .

That is why restorers are investigating how to put a protective film on monuments without preventing the gas exchange through the rock.

With information from:

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