Simulation Experiment Study on Impacting the δD Value of Aromatic Compounds. (18th April 2023) - Duan, Yi
Abstract : Little is known about the effects of sedimentary environment and maturity on δ D values of aromatic compounds deposited in geological bodies. Our simulation experiments showed that the δ D value of pyrolytic polycyclic aromatic hydrocarbons (PAHs) was significantly different between the studied samples from high and low latitude regions. Comparative studies showed that the δ D values of PAHs produced by pyrolysis were related to those of water in the two regions. With increasing maturity, the δ D value of the PAHs becomes higher. Additionally, it was observed that some PAHs exhibited a propensity to increase the δ D value upon demethylation. The thermodynamic fractionation of hydrogen isotopes between the PAHs produced by pyrolysis and both the n -alkanes and methane produced by pyrolysis indicated that the hydrogen isotopic value of the PAHs was higher than that of the n -alkanes or methane. The long-chain alkylbenzene produced by pyrolysis has a higher mean δ D value compared with the n -alkanes produced by pyrolysis, but it is lower than that of the PAHs in the same sample. The lowest δ D value among the aromatics was found in the ring A monoaromatic steroids produced by pyrolysis. The low δ D values of these steroids should originate from isotopic fractionation during isoprenoid lipid biosynthesis.