Plant waxes are long-chain alkanes and alkanoic acids that derive largely from leaf cuticles. They are commonly used by organic geochemists because they carry information related to paleoecology. In an individual plant, the ratio of 13C/12C in plant waxes relates to carbon cycling: what was the 13C/12C of atmospheric CO2 when the plant grew? What was the concentration of CO2? To what degree does the 13C/12C in plant material differ from source CO2 due to plant physiology?
Similarly, the ratio of deuterium (D) to hydrogen (H) in plant wax is a function of D/H in the environment, as well as physiological factors that affect how hydrogen is incorporated into plant waxes. The D/H of water in the environment changes as a function of hydrological and climatic factors, and so plant waxes have the potential to preserve paleoenvironmental information.
Plant waxes preserved in sediments and sedimentary rocks are a complex mix of different waxes from different plants of different ages, grown at different times of the year. We investigate the effects of plant phylogeny and physiology, in the hope that this will allow us to arrive at a better understanding of how to interpret these complex mixture of paleoenvironmental signals.