Effects of climate variability on mercury deposition during the Older Dryas and Younger Dryas in the Venezuelan Andes

Abstract

We present a high-resolution record of Late Glacial and Early Holocene mercury (Hg) accumulation within the sediments of Laguna de Los Anteojos, a small headwater alpine lake in Venezuela. Our sediment core spans the Older Dryas (OD) andYounger Dryas (YD) climate reversals, providing new insight into the effects of abrupt climatic transitions on atmospheric Hg deposition. Sediment Hg concentrations and accumulation rates (fluxes) increased sharply after regional deglaciation and then peaked immediately prior to onset of both the OD and YD. Mercury concentrations and fluxes then decreased through cold OD and YD conditions. Both Hg concentrations and fluxes increased rapidly with warming, rising two-fold in about 100 years after the OD and nearly four-fold in about 500 years during the latter-half of the YD. This lake-sediment record of Hg dynamics during the Glacial-Holocene transition suggests atmospheric Hg cycling is affected by abrupt climate change.