New research reveals that two of the largest reservoirs at Tikal, an ancient Maya city in what is now northern Guatemala, were contaminated with high levels of mercury, phosphate and cyanobacteria known to produce deadly toxins. The ancient Maya city of Tikal in northern Guatemala. Image credit: Gerd Eichmann / CC BY-SA 4.0. Tikal is one of the largest archaeological sites and political, economic and military centers of the pre-Columbian Maya civilization. The...