Mayans’ enthusiastic use of mercury helped the toxin infiltrate the Yucatán environment

The use of mercury by the ancient Maya for ceremonies, religious events, and decoration spread the pollutant even further throughout the region than previously known, new research finds. A new study has identified extremely high levels of mercury dated to the Classic Period (250-920 CE) in lake cores from the Yucatán lowlands – a region where contamination had not yet been documented. The ancient Maya used mercury in the form of the red mineral cinnabar as paint. While studies have largely focused on environmental mercury toxicity in communities in the southern highlands and south-central lowlands, Matthew Neal Waters and colleagues have now found that mercury also infiltrated the Yucatán Peninsula during the Classic Period. They examined sediment cores from Lago Cobá and Cenote Xcach, and determined that levels of mercury surpassed modern safety thresholds by orders of magnitude for centuries. The cores also contained proof of aquatic food web collapse across trophic levels linked to times of heightened mercury. “Whereas climate-associated reductions in water quantity are well established as a regional stressor for the ancient Maya, our results suggest that declining water quality driven by [mercury] contamination constituted an additional and previously underappreciated environmental stressor,” Waters et al. write.