PP003-0010
Influence of tropical cyclones rain on the δ18O drip water composition at Río Secreto Cave in the Yucatan Peninsula, Mexico.

Monday, 7 December 2020
Poster
Maria FERNANDA Lases-Hernandez1, Martin A Medina-Elizalde2, Amy E Frappier3, J P Bernal1, Patricia A Beddows4 and Matthew DeCesare5, (1)Universidad Nacional Autonoma de Mexico, Mexico City, Mexico, (2)University of Massachusetts Amherst, Amherst, MA, United States, (3)Skidmore College, Geosciences, Saratoga Springs, NY, United States, (4)Northwestern University, Evanston, IL, United States, (5)Auburn University, Department of Geosciences, Auburn, AL, United States
Abstract:
Abstract

This study examines the oxygen isotopic composition (δ18O values) of drip water, rainfall, and groundwater in the Río Secreto cave system, located in the Yucatán Peninsula, Mexico. The main motivation of this study was to determine the implications of drip water hydrology for the reconstruction of rainfall, droughts and tropical cyclone activity from stalagmite δ18O records. Monitoring of environmental and isotopic conditions was conducted for two years, from June 2017 to April 2019. Observed bi-weekly to interannual variability in drip water δ18O values can be explained for individual drips by different integrations of rainfall amount in the time domain. Drip sites in two chambers (Stations A and B) integrate 4 to 15 months of rainfall accumulation. In a third chamber (Station LF) one drip site reflects the annual rainfall isotopic cycle with a positive offset and another, the largest rainfall events. During epikarst infiltration, the integration of rainfall amount by drip water source reservoirs determines the degree to which they “dilute” a tropical cyclone (TC) isotopic signature. TCs can be detected particularly when: (1) the water volume of the reservoir is low, such as during a persistent meteorological drought, and; (2) TCs have a sufficiently distinct isotopic signal relative to that of the reservoir prior to the event. TC isotopic signals can be masked or attenuated when drip water samples integrate more than a week and if significant rainfall events proceed the TC. In Río Secreto cave, reconstructing precipitation amount and detecting the TC isotopic signatures from stalagmite δ18O records is possible. This study complements the results from Lases-Hernandez et al. (2019) comparing two different sampling protocols of drip water collection. We highlight the importance of conducting multiyear monitoring of drip water and rainfall in order to interpret stalagmite δ18O as a paleoclimate proxy.

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