Identification of di- and triterpenoid lipid tracers confirms the significant role of autoxidation in the degradation of terrestrial vascular plant material in the Canadian Arctic

Autoxidation products of specific lipid components of angiosperms (betulin, α- and β-amyrin) and gymnosperms (dehydroabietic acid) and their parent compound in surface sediments from different regions of the Canadian Arctic were quantified. The high proportions of these autoxidation products in all the sediments (mean 60.1 ± 14.0%, 91.8 ± 1.1, 98.7 ± 2.2 and 96.6 ± 5.4% for dehydroabietic acid, betulin and α- and β-amyrin, respectively) confirmed, unambiguously, the important role played by autoxidation in the degradation of vascular plant material in the region and its enhancement in seawater. The enhancement of these processes in Arctic waters could be the result of intense photooxidation during the senescence of the organisms within the terrestrial environment.