On 05/22/10, emulsified form of MC 252oil was collected from Belle Pass near Port Fourchon in Lafourche Parish, LA and used for biodegradation studies. The objectives of this study were to determine the hydrocarbon composition of the emulsified oil, extent of biodegradation of emulsified oil and the change in microbial population. Soil cores were obtained from the salt marshes in Lafourche Parish, LA using aluminum core device and transferred to glass cores (15 cm dia × 100 cm long) and incubated inside a greenhouse. Approximately, 100 g of the emulsified oil was added to cores consistent with oil loadings observed in the field. Replicate cores were used to evaluate three treatment conditions; (i) natural attenuation with existing nutrient concentrations, (ii) nitrogen amendment and (iii) nitrogen + sulfate amendment. The cores were maintained with approximately 1” layer of synthetic seawater above sediment. For each treatment, cores were sacrificed for oil analysis every 30 days for the first three months (short-term fate) and after approximately a year (long-term fate). The cores were cut from the top and polycyclic aromatic hydrocarbons were analyzed from the soil sections 0–2 cm, 2–4 cm and 8–10 cm. Composition of the emulsified oil was characterized as the ratio of the compound analyzed to hopanes. Short-term incubations demonstrated limited biodegradation of key PAHs. Only phenanthrene biodegraded to any statistically significant extent in treatments over the first 3 months. Over the long-term (~1 year), biodegradation of phenanthrenes and dibenzothiophenes was observed and biodegradation extent was greater in fertilized treatments. Spontaneous breaking of emulsions was observed in several cores and this may precede biodegradation. Microbial community structure indicated diverse but different microbial populations in the three treatments.
