Stable source of Holocene spring precipitation recorded in leaf wax hydrogen-isotope ratios from two New York lakes

Changes in synoptic atmospheric circulation patterns are thought to play a role in establishing millennial scale climate periods during the end of the late glacial and the Holocene. In the northeastern United States, multi-proxy evidence documents fluctuations in effective moisture and temperatures for this time period, but constraining the relationship between atmospheric processes and these climate regimes is not straightforward. Because the hydrogen-isotope ratios of sedimentary terrestrial leaf waxes can reflect precipitation delta D, these long-chain hydrocarbon compounds are an excellent tool to investigate moisture sourcing. Here we present lake sediment and leaf wax carbon- and hydrogen-isotope records that span the past similar to 14.0 thousand years from Heart Lake and Moose Pond in the Adirondack Mountains (ADK), New York. High initial lake productivity after basin inception is reflected in low C:N ratios (<15), and higher relative short chain n-alkane (n-C-17, n-C-19, and n-C-21) to long chain n-alkane (n-C-27, n-C(29)and n-C-31) concentration ratios. The Holocene record is characterized by low bulk and n-alkane delta C-13 (similar to -28 parts per thousand, similar to -31 parts per thousand, respectively), high ACL(25-35), (-28), and high relative concentrations of long chain n-alkane homologues, indicating a dominantly terrestrial source of organic matter for this time period. Hydrogenisotope ratios of n-C-29 n-alkane from both lake basins range only similar to 20 parts per thousand through the Holocene and reconstructed precipitation delta D (delta D-precip) from both basins is in good agreement with that of modern modeled spring precipitation. This suggests there may have been no major changes in the sourcing of spring precipitation for the ADK throughout the time of record. (C) 2020 Elsevier Ltd. All rights reserved.