FATE AND PERSISTENCE OF LONG-TERM SPILLED METULA OIL IN THE MARINE SALT MARSH ENVIRONMENT: DEGRADATION OF PETROLEUM BIOMARKERS

摘要

Complete “total oil analyses” were performed on the 24-year-old spilled Metula oil samples collected during the 1998 field visit. Fingerprinting data clearly indicate, except those three samples collected from the East Marsh untreated plots (EEGO, EE-C1 and EE-C2) that were only moderately weathered, the spilled oil has undergone significant alteration in chemical composition after 24 years. There are no fundamental differences between heavily weathered and degraded West Marsh and treated East Marsh samples. However, the effect of the experimental tilling action has been to promote plant recolonization. This result indicates that the recolonization of the marshes almost certain would have been accelerated had tilling or mixing been conducted on these sites after the spill. Chemical analyses of the two asphalt pavement samples (WI-1 and WI-2) indicate extremely heavy degradation. For these two samples, complete spectrum of n-alkanes from C8 to C40 and greater than 98% of alkylated PAH homologues were lost, and even the highly biodegradation-resistant biomarker compounds were shown to be more or less altered. It is observed that biomarkers were generally degraded in the declining order of importance as follows: diasteranes > C27 steranes > tricyclic terpanes > pentacyclic terpanes > norhapanes ～C29 αββ steranes.