IDENTIFYING BASIN-SPECIFIC CONTROLS ON LEAF WAX RECORDS IN LAKE SEDIMENTS OF THE ADIRONDACK MOUNTAINS, NEW YORK

The hydrogen isotopic composition of leaf waxes (dD_wax) primarily reflects that of plant source water. Therefore, sedimentary δD_wax records are increasingly used to reconstruct the δD of past precipitation (δD_p) and to investigate paleohydrologic changes. Such reconstructions rely on estimates of apparent fractionation (ε_app) between δD_p and the resulting δD_wax. While numerous studies have calibrated ε_app offsets between modern δD_p and δD_wax in living plants, relatively few have assessed the effects of leaf wax integration, transport and deposition on ε_app values in sediments. Here, we evaluate the influence of basin-specific factors on sedimentary leaf wax composition from multiple lakes in the same region with similar local δD_p.

We report δD_wax and ε_app values from the uppermost sediments of seven lakes within the Adirondack Mountains in NY that vary in terms of their vegetation structure, basin size, shoreline slopes, surface erosion and fluvial inputs. Leaf wax analyses include n-alkanes and n-alkanoic acids, both of which are commonly applied in paleohydrology reconstructions. Molecular and isotopic leaf wax data from each lake are interpreted in the context of sediment properties including grain size, bulk organic content, and bulk sediment δ¹³C and C:N ratios. We compare ε_app values among lakes and investigate potential relationships with basin morphology, sediment composition and transport processes specific to each site. We also compare the abundance, molecular distribution and δD_wax composition among two major leaf wax classes (n-alkanes and n-alkanoic acids) to examine differences in fractionation between these compounds at the sediment level.