In Danger One of the Largest Aquifers in the World, the Great Mayan Aquifer, Based on Monitoring the Cenotes of the Yucatan Peninsula.

The aquifer flowing beneath the Yucatan Peninsula, Mexico, is one of the largest in the world and is in direct contact with the surface through "cenotes" (sinkholes) that have been documented to be contaminated with various classes of pollutants. The objective of this study was to evaluate the environmental status of the Great Mayan Aquifer through a review of data published on pollution of the cenotes. Approximately 1000 known georeferenced cenotes on the Yucatan Peninsula were geographically located. A map was generated using the geographic information system software. High-resolution satellite images were processed to complement the "QuickMap Services" and the formatting service of the Environmental Systems Research Institute. From the literature, 173 cenotes were identified as being sampled for various pollutants, and of these, one or more classes of pollutants were detected in 160 (i.e., greater than 92%) of the cenotes. Pollutants reported to be present included bacteria and viruses of human origin, fecal sterols, polycyclic aromatic hydrocarbons (PAHs), pesticides, pharmaceuticals, illicit drugs and personal care products. From the review of the literature, only 13 cenotes were reported to be free of the target pollutants. From this study, it can be concluded that the aquifer system with the Yucatan Peninsula is vulnerable to contamination from pollutants originating from wastewater, as well as surface runoff and infiltration from urban and agricultural lands.