Holocene Climate Change and its Effect on the Mayan Aquifer of the Yucatan Peninsula, Mexico

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Every year, thousands of Canadians vacation at large resorts on the Yucatan Peninsula's Maya Riviera; often swimming in nearby cenotes during their stay. Most are not aware that these cenotes are entry points for a vast subterranean cave system that extends beneath the resorts which is an important aquifer for the local population. This aquifer is under increased threat from human development through groundwater extraction and waste contamination. The aquifer is also very sensitive to larger scale factors such as global sea-level rise which is predicted to be 1m by the end of the 21st century, as well as other effects of climate change (e.g. precipitation, frequency of hurricanes). The long-term goal of my research program is to examine the hydrological evolution of karst aquifers and their relationship with Holocene climate and sea-level change with a focus on the Yucatan Peninsula. Karst aquifers predominate coastal areas around world, but especially in tropical and subtropical areas where millennia of reef growth coupled with sea and land-level change has resulted in large tracts of porous limestone. These karst aquifers (anchialine) are a meteoric water mass resting on top of a marine water mass that intrudes from the coast through the porous limestone. Because the Neogene/Quaternary limestone of the Yucatan peninsula is so porous, rainwater penetrates to the water table and flows to the coast with the salinity of the meteoric water mass being controlled by flow patterns at the halocline, but the relationship is poorly known. So, although we have a general understanding (instrumental monitoring) on how the water masses interact under normal conditions, the complexity of the relationship is not well understood, and there is little knowledge on how water masses responded to Holocene sea-level rise and climate change. The proposed research program will develop a new paleoenvironmental indicator (chlorine) in sediment cores for reconstructing the long-term evolution of the anchialine aquifer of the Yucatan and examine relationships with climate cycles establishing boundary conditions and future impacts on the aquifer. The outcomes from this research will also contribute to important archaeological questions regarding Paleoamericans who migrated to the Yucatan approximately 12-13,000 yrs ago, and to the debate about the decline of the Classic Maya which has been linked to a period of drought in the 8th and 9th c. AD. The rise and fall of Mayan societies in the Yucatan have been linked with climatically wet and dry periods, although there is spatial complexity in this relationship that remains unexplained and is highly debated amongst researchers. The proposed research will contribute to this debate by reconstructing the salinity or (potability) of the aquifer and lake water over the past 4-5,000 years.