Patterns of Groundwater Salinization in the Yucatan Peninsula: Insights into the Ancient Karstic Maya Aquifer

The Yucatan Peninsula, situated in the Gulf of Mexico, is characterized by a unique karst topography that sustains groundwater-dependent ecosystems and holds significant archaeological sites of the Maya civilization. Despite its environmental and cultural importance, the region faces considerable challenges related to water quality. The karst landscape allows for easy infiltration of contaminants, while an extensive seawater wedge beneath the aquifer and the dissolution of gypsum from the Paleocene formations in the southern peninsula further limit the availability of freshwater. These factors complicate the provision of potable water, particularly in an area with insufficient sanitation infrastructure and a limited understanding of the aquifer system. This study offers the first detailed analysis of regional water quality trends in the Yucatan Peninsula, based on 1528 water quality samples collected from 1998 to 2022. Using pattern recognition of major ions along with dimensional reduction, network clustering, and traditional hydrogeochemical techniques, the study identifies key factors driving salinization across the region. Fourteen clusters were identified, linked to seawater intrusion, gypsum dissolution, widespread carbonate dissolution, and nitrate leaching. Approximately 23% of water samples from human-use sources exceeded acceptable sulfate and nitrate levels. The findings emphasize the critical need for ongoing water quality monitoring to inform future management strategies, particularly in the face of population growth, tourism, and climate change.