Lire en français · Auf Deutsch lesen · Leer en español
Traces of mercury have been identified in sediment cores taken from lake bottoms near the sites of Coba and Xcach on the Yucatán Peninsula, in Mexico. According to Archaeology magazine, which picks up a report from Reuters, this contamination affected Maya cities after Tikal, in Guatemala. The study, published in the journal Science Advances, suggests exposure to the metal over several centuries.
A red pigment behind the pollution
The Maya used cinnabar, a bright red pigment that contains mercury, in their ceremonies and funerary rites. It was also used to paint frescoes and decorate temples. This practice, well documented in the major centers of Classic Maya civilization, still leaves traces in the environment.
Cinnabar is a mercury sulfide. When heated, handled or dispersed, it releases metal that can settle into soils and waters. Lake sediments then preserve a chronology of these successive inputs, allowing researchers to reconstruct the history of the pollution long after the practices that caused it had ended.
Lake cores used to date the contamination
According to Matt Waters of Auburn University and Savanna Wooten of the Jones Center at Ichauway, the researchers collected cores from the lake beds at the sites of Coba and Xcach. These sediment layers act as a natural archive, in which each level corresponds to a given period.
The results show several mercury peaks. At Coba, a rise begins around 250 CE and lasts about 150 years. At Xcach, a peak occurs between 125 and 200, followed by a second around 250. A third peak appears between 535 and 820, a period close to the end of the Classic phase and the collapse of some Maya cities.
Contamination that reached the food chain
The researchers also measured several biological markers in the sediments: bacteria, algae, cyanobacteria, shelled organisms and midge larvae. These indicators declined or disappeared in the lakes at the time of the peaks, signaling that mercury affected several levels of the aquatic food chain.
In Matt Waters' view, the levels reached far exceeded current toxicological standards and anti-pollution regulations, and this persisted for centuries around Coba and Xcach. This situation suggests that inhabitants could have been exposed by consuming contaminated water and fish.
A phenomenon that goes beyond a single city
An earlier study had already confirmed the presence of mercury at the site of Tikal, in Guatemala. The new analyses show that the phenomenon was not confined to an isolated city but affected several sites across the Maya region.
These data make it possible to assess the impact of ritual practices on the environment and on the health of populations, a subject still little documented for Maya civilization. They also invite us to consider mercury as an element of the ecological history of the Yucatán Peninsula.
What this research reveals
By linking the chronology of the mercury peaks to the major stages of Maya history, this work opens a line of inquiry into the connections between pollution, ceremonial use and the decline of certain cities. However, it does not by itself establish a single cause for the collapse of the Classic period, which most likely resulted from multiple factors.
To explore this subject further, visitors can go to the sites of the Yucatán Peninsula and Guatemala, where the remains of temples and frescoes testify to the richness of Maya culture. Interested readers can also consult the original scientific article published in Science Advances.
Frequently asked questions
Why were the Maya exposed to mercury?
The Maya used cinnabar, a red pigment containing mercury, for ceremonies, funerary rites and temple decoration. The dispersal of this pigment contaminated soils and waters. The lakes then preserved traces of this pollution.
Where was mercury found in Maya cities?
Traces of mercury have been identified in sediment cores taken from lakes near Coba and Xcach on the Yucatán Peninsula. An earlier study had also confirmed contamination at Tikal, in Guatemala.
How did researchers date the mercury pollution?
Scientists analyzed the successive layers of lake sediments, which preserve a chronological record of deposits. This method makes it possible to place the mercury peaks between the 2nd and 9th centuries CE.
Does mercury contamination explain the fall of Maya cities?
The data show a mercury peak close to the end of the Classic period, but they are not enough to point to a single cause. The decline of Maya cities most likely resulted from several combined factors.
Sources
- How Many Maya Cities Were Contaminated with Mercury? — Archaeology Magazine
Original summary written with the help of artificial intelligence from the sources cited, checked automatically, then translated from the French original. Information and quotations belong to their authors. Read the French original.
