Analysis of compound-specific hydrogen isotopes from lacustrine sediments to establish Holocene paleoprecipitation dynamics at Laguna Arancibia, Costa Rica

Keywords: drought, climate change, compound-specific isotopes, hydrogen, carbon
Session Type: Virtual Poster Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 03:40 PM (Eastern Time (US & Canada)) - 2/27/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 27

Abstract

Compound-specific isotopes of n-alkanes found in lake sediments can provide useful information on prehistoric environmental conditions. n-Alkane carbon and hydrogen isotope compositions are used to reconstruct paleovegetation and paleoprecipitation, respectively. Using compound-specific isotope analysis of n-alkanes, we aim to deconvolve potential climate forcing mechanisms responsible for extended periods of drought in Central America during the Late Holocene. Multiple climate forcing mechanisms from both the Atlantic and Pacific Oceans affect the precipitation dynamics in Central America, including the migration of the intertropical convergence zone, the North Atlantic Oscillation, and the El Niño- Southern Oscillation/Pacific Decadal Oscillation. Atlantic forcing mechanisms have been regarded as the primary drivers for drought events such as the Terminal Classic Drought and Little Ice Age, but this conclusion may be biased by a shortage of paleoprecipitation records from sites in the Pacific basin. Laguna Arancibia, located at 1250 m elevation on the Pacific slope of the Cordillera de Tilarán in Costa Rica, provides an opportunity to help fill this gap. Here we analyze 41 sub-samples from a sediment core recovered from Laguna Arancibia for n-alkane carbon and hydrogen isotope composition. The new precipitation and vegetation records will be compared to existing records in this region to determine how different sites responded to established drought events. Deciphering these forcing mechanisms will potentially provide insight into future responses of precipitation regimes to the same forcing mechanisms as a result of global climate change.