Isotope hydrogeochemistry and physico-chemistry of Lago Enriquillo (Dominican Republic) and its tributaries

Tropical cyclones (TCs) such as hurricanes are amongst the most devastating natural disasters of the modern world causing massive humanitarian, ecological, and economic damage every year. A better understanding of timing and frequency of TCs must, therefore, be a key priority for building resilience of affected countries. Within this project, we investigate a stable isotope-based approach for the reconstruction of paleo-TCs through the integration of ecological and morphological data with isotope geochemical signatures of modern ostracodes in relation to the hydrochemistry from a tropical lake located within the Main Development Region of TCs (Lago Enriquillo, Dominican Republic). Water samples were taken during two seasons in 2022 on different vertical profiles through the lake, associated tributaries and closed-by water bodies. Besides in-situ characterization, samples were taken for major, minor, and trace elements using different analytical approaches, and the stable isotope signatures of water (²H, ¹⁸O; CRDS spectroscopy), dissolved inorganic carbon (¹³C; gas mass spectrometry), and sulfate (³⁴S, ¹⁸O; gas mass spectrometry). Hydrochemical data were further evaluated using the speciation model PHREEQC.

Substantial changes in the lake composition were observed between the two campaigns. Together with an evaluation of element stoichiometries, the water isotopes allow for an evaluation of sources and evapotranspiration. Carbon and sulfur isotopes allow to deduce the role of microbial activity and solution-atmosphere exchange on the modulation of the dissolved carbon system, in contact with solid phase carbonates, like ostracod shells