Use of compound-specific stable isotope analysis to source anthropogenic natural gas-derived polycyclic aromatic hydrocarbons in a lagoon sediment

This paper reports the first identification of polycyclic aromatic hydrocarbons (PAHs) in the environment with extremely low carbon stable isotopic ratios. For sediments collected from a coastal lagoon in northern Italy, these low C-13/C-12 isotopic ratios for many of the PAHs together with the presence of cylcopentafused PAHs (CP-PAH) indicate that the PAHs have predominantly been derived from a high-temperature industrial process utilizing the local biogenic natural gas. The process used the biogenic gas as the feedstock for the production of acetylene. From the evidence available, the large variability in the PAH isotopic delta C-13 values (from -31 to -62 parts per thousand) is ascribed mainly to biodegradation rather than to major inputs from sources of isotopically heavy PAH, such as the neighboring modern-day carbon black plants.