This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Ancient Maya communities made extensive use of liquid mercury and a red, mercury-containing pigment called cinnabar to decorate buildings, pottery and burial sites. Unsurprisingly, as previous research has shown, this led to mercury contamination of soils and reservoirs at some Maya sites.
And that pollution may have spread even farther into their territory and caused the collapse of two lake ecosystems, according to a study published in the journal Science Advances. To determine the extent of mercury contamination and what the ancient populations may have been exposed to, researchers led by Matthew Neal Waters at Auburn University in Alabama extracted sediment cores from Lago Cobá and Cenote Xcach on the northern Yucatán Peninsula. This area was once part of the ancient Maya Lowlands.
Back in the lab, the first step was to determine when the sediment layers were deposited. Radiocarbon dating of charcoal and wood fragments showed that some of the sediments were more than 2,000 years old. Next, the researchers measured mercury concentrations in different layers to see how pollution levels had changed over time.
They then compared the mercury concentrations with modern sediment safety guidelines to determine whether they had reached levels that could have harmed ancient aquatic life. The team also looked for evidence of possible harm in traces of algae and bacteria, as well as remains of small aquatic animals buried in the sediments. The results suggest that the Maya's use of mercury came at a considerable cost.
At Lago Cobá, mercury concentrations began rising around A.D. 40, peaking around A.D. 250 to 300 before returning to background levels around A.D. 520. Meanwhile, at Cenote Xcach, contamination was more severe and lasted longer. Mercury concentrations reached levels considered severely harmful to aquatic life for several centuries, peaking around A.D. 720.
These periods of high contamination coincided with dramatic changes in the lake ecosystems. Traces of algae and bacteria declined sharply, while the remains of tiny aquatic animals disappeared or became much less abundant. Sediment cores from two other lakes showed no elevated mercury concentrations, ruling out a widespread atmospheric source of contamination.
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