Mayan cities were dangerously polluted with mercury
(ORDO NEWS) — The Mayan Empire dominated vast areas of Mesoamerica for over 3,000 years.
But despite their impressive record of survival, the Mayan civilization did not live in complete harmony with its environment, as a review article published by Frontiers in Environmental Science makes clear.
Surprisingly, for the Maya, mercury poisoning was a serious problem.
It seems that the Mayan people faced a serious environmental problem. The problem was mercury contamination, which was found to be at shockingly high levels in measurements of soil samples taken from several Maya settlements in southern Mexico and northern Central America.
“Environmental mercury pollution is commonly seen in modern urban areas and industrial landscapes,” said study lead author Dr Duncan Cook, professor of geography at the Australian Catholic University.
“The discovery of mercury deep in soil and sediment in ancient Mayan cities is difficult to explain until we start looking at the archeology of the region, which tells us that the Maya have been using mercury for centuries.”
The discovery of the Maya mercury problem did not come from any new research, but from a careful review of past research.
Dr. Cook joined geography professors from the United States and the United Kingdom to study the results of chemical analyzes of soil and sediment collected from May 11 archaeological sites in Mexico, Belize, Honduras, Guatemala and El Salvador. The tests were carried out on soil samples from the classical period (AD 250–900).
Scientists were alarmed to find that ten of these locations contained measurable amounts of mercury, a notorious heavy metal toxin. Concentrations ranged from 0.016 ppm at Actunkan in western Belize to an astounding 17.16 ppm at the ancient city of Tikal in northern Guatemala.
The current toxicity threshold (the point at which exposure to a substance poses a health hazard) for mercury in sediments is set at one part per million. This means that the soil in Tikal was 17 times more polluted than this original figure.
This result from Tikal confirmed the findings of a team of researchers led by scientists from the University of Cincinnati who published a study in Scientific Reports in 2020 showing that two ancient Mayan reservoirs in Tikal were so contaminated with mercury and algae that the water could have been undrinkable.
The obvious question is: what caused such high levels of mercury in the areas inhabited by the Maya who lived during the classical period, the time when the Maya empire reached the peak of its social, cultural and economic development?
The ancient Maya made extensive use of a soft metallic substance known as cinnabar, a form of mercury sulfide that can be recycled to make brick-red paints and powders, according to scientists involved in the new study.
Previous research indicates that the Maya used a vast array of cinnabar-based products to decorate their bodies, pottery, the walls of their houses, and other stone structures, including stone monuments.
After their initial application, the layers of this cinnabar would have been washed away by rain or broken down by dust, wind, and indoor humidity, releasing a continuous stream of trace mercury into the environment, which would gradually build up in the soil and groundwater.
As decades passed, and in some cases years, mercury pollution rose to toxic levels, causing a torrent of health problems that probably baffled the Maya living in the most polluted villages or areas.
As dangerous as the mercury in cinnabar was, it was even more toxic in its pure form, and the Maya used it in that form as well.
During excavations at several Maya sites, sealed vessels filled with liquid mercury were found, which proves that they used mercury in noticeable quantities for various practical and ceremonial purposes.
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