δD values of individual n-alkanes from terrestrial plants along a climatic gradient - Implications for the sedimentary biomarker record

Our results prove that terrestrial n-alkane δD values record the δD value of precipitation, modified by the amount of isotope enrichment in the leaf water due to plant anatomy (stomata vs. no stomata) and site specific meteorological conditions, such as evapotranspiration, relative humidity and soil moisture. Therefore, terrestrial n-alkanes in lake sediments can deliver information on changes in these parameters over geological timescales. In lake sediments where aquatic n-alkanes, such as n-C17 record the lake water δD value, the isotopic difference between terrestrial and aquatic n-alkanes could therefore be used to reconstruct changes in evapotranspiration.