Pollution menaces pre-Columbian heritage

Jan 27, 2007 09:10 GMT  ·  By

The only way to study the enigmatic pre-Colombian civilization remains the research on ruins they left behind.

But if they resisted the Spanish conquistadors, now modern pollution is defeating them forever. Contamination is menacing to erase thousand-year-old stone carvings at Mexico's most important archaeological sites.

The El Tajin city, the center of the Totonac civilization that flourished between 9 to 13th century A.D., on Mexico's Veracruz Gulf coast, is known for its temple pyramids and beautiful carved reliefs. "Acidic air pollutants pumped out by oil-drilling platforms and power stations along the coast are slowly eroding these carvings," said Humberto Bravo, an air pollution specialist. "The deterioration is alarming ? and could cause irreparable damage to monuments that are an important part of our cultural heritage," said Bravo, of the University of Mexico's Center for Atmospheric Sciences.

Tajin was the Totonac god of thunder and most of the ruins are to be dug up.

The most impressing construction is a complex niche-studded pyramid, but there are also other temple pyramids, palaces, and courts for playing a ritual ball game, also discovered in the case of other Mesoamerican civilizations (Maya, Aztec). But this is the richest site depicting the game: a lot of carving showing ball players and their equipment.

It is not known how they played the game, but it could have been used as an exercise for young warriors and those who lost the game would have been executed. "Now the carvings depicting the game are beginning to erode at an alarming rate. Within 10, 20, or 100 years, these hieroglyphics will disappear if we don't do anything about it," Bravo said.

El Tajin's soft limestone buildings are extremely vulnerable to contaminants like chlorine, sulfates, and nitrates expelled in the air from power stations and oil refineries. Sulfates and nitrates react with rain water, forming the sulfuric and nitric acids, which dissolve the calcium carbonate to carbon dioxide and gypsum, a salt easily washed away. "The Veracruz region has some of the highest acid levels in the air in Mexico," Bravo said. "The art of El Tajin is crucial to our understanding of the ancient history of the Gulf coast," said John Machado, a pre-Columbian art historian at Chaffey College in Rancho Cucamonga, California.

"It gives evidence of a powerful and complex civilization that had broad interaction with Mesoamerican cultures in both central Mexico and Maya-controlled regions but still cultivated its own unique Veracruz style and iconography."

"The loss of these images would be devastating to the cultural heritage of the area," said Machado, who has done extensive research at El Tajin.

But this is not the only affected Mexican site. "The sources of degradation vary," said Maria Lourdes Gallardo, chief conservator at the main Aztec temple, Templo Mayor, in Mexico City. "The pollutants ? in the archaeological zone of Templo Mayor ? range from the smog to water filtrations underground," Gallardo said.

"We found that there had been a significant change in the rate of pollutants derived from sulfur, which had diminished considerably, compared to an increase in the quantity of chloride and heavy metal pollutants."

Also, the Chalcatzingo in Morelos, 60 miles (97 kilometers) south of Mexico City, containing some Olmec-style bas-relief carvings dated 700 B.C. in granodiorite, a much harder rock than limestone, is affected. "I can document with 30 years of photographs just how acid rain is destroying those magnificent works of art. The details are slowly disappearing." said David Grove, a professor emeritus of anthropology at the University of Illinois at Urbana-Champaign.