The Maya used so much red cinnabar paint that mercury poisoned their lakes for centuries

In brief 3 key points

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• Mercury in two Yucatán lakes spiked during the Classic Maya period
• Levels exceeded modern sediment guidelines for centuries
• Algae, tiny crustaceans and midge larvae declined when mercury was high

The ancient Maya painted temples, pottery and even their dead with cinnabar, a bright red mercury mineral. A new study finds that the mercury ended up in two lakes on the Yucatán Peninsula of Mexico. It stayed there at toxic levels for centuries.

Matthew Waters, a paleolimnologist at Auburn University in Alabama, led the study in Science Advances. Earlier work had found mercury pollution in Maya areas further south. No one had documented it in the Yucatán lowlands.

Off the charts

The team pulled cores of mud from the bottom of Lago Cobá, beside the Maya city of Cobá, and from Cenote Xcach, a flooded sinkhole near a little-excavated ruined city. The cores record more than 2,000 years.

“The mercury data was crazy. Off the charts. These mercury levels aren't normal.”

Matthew Waters, Auburn University

At Lago Cobá, mercury stayed above the probable effect concentration, a benchmark for likely harm to life in the sediment, for more than 200 years. For nearly a century it was above the severe effect level. At Cenote Xcach it peaked at six times the severe level for about 300 years, then dropped sharply around AD 850.

Life in the water collapsed

In the same layers, markers of algae, cyanobacteria and purple sulfur bacteria declined. Shells of ostracods, tiny crustaceans, were missing. Researchers at the University of Southampton found that the dominant species of midge larvae declined too. The communities recovered when the mercury fell.

Cinnabar does not occur naturally in the Yucatán, so the researchers think it was imported. At Cobá the pollution fell to background levels by about AD 520, but at Xcach it continued much longer.

Waters does not suggest that mercury caused the Maya collapse. The authors call declining water quality an additional, previously underappreciated stressor alongside drought. Waters has no sediment data yet on fish or other larger animals.

Sources (3)

Peer-reviewed paperfrom Auburn University and University of Southampton

• The Maya used so much red paint that they poisoned their water with mercury, mud sediments reveal (Live Science: archaeology)
• The Maya used so much red cinnabar paint that mercury poisoned their lakes (EurekAlert! (AAAS))
• The Maya used so much red cinnabar paint that mercury poisoned their lakes (Auburn University)

Paper: Waters et al., Toxic mercury, aquatic ecosystem collapse, and the ancient Lowland Maya, Science Advances 12(45), eaeh3280 (2026)

Edited by Guiseppe Weijermars

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mayamercurycinnabaryucatanpollution

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