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 hydrocar bons (PAHs) in the environment with extremely low carbon stable isotopic ra tios. For sediments collected from a coastal lagoon in northern Italy, thes e low C-13/C-12 isotopic ratios for many of the PAHs together with the pres ence of cylcopentafused PAHs (CP-PAH) indicate that the PAHs have predomina ntly been derived from a high-temperature industrial process utilizing the local biogenic natural gas. The process used the biogenic gas as the feedst ock 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 p er thousand) is ascribed mainly to biodegradation rather than to major inpu ts from sources of isotopically heavy PAH, such as the neighboring modern-d ay carbon black plants.