Investigating Hydrogen Isotope Variation during Heating of n-Alkanes under Limited Oxygen Conditions: Implications for Palaeoclimate Reconstruction in Archaeological Settings

This paper reports on a series of heating experiments that focus on n-alkanes extracted from leaf, bark, and xylem tissues of the Celtis australis plant. These lipid biomarkers were analysed for their compound-specific hydrogen isotopic composition (delta H-2(wax)) under limited oxygen conditions at 150, 250, 350, and 450 degrees C. Our results reveal isotopic variations in wax lipids of different plant organs during short-term low-temperature combustion. We conclude that, in the absence of a detailed characterisation of the depositional environment in advance of sampling, delta H-2(wax) values in archaeological or otherwise highly anthropogenic environments should be interpreted cautiously. In addition, we observed that variation in delta H-2(wax) of leaves is minimal at temperatures <= 350 degrees C, highlighting the potential for delta H-2(wax) in thermally altered combustion substrates to yield palaeoclimate information, which could allow researchers to investigate links between archaeological and climatic records at a high spatial and temporal resolution.