| Abstract
| - Cerro Negro bitumen, separated from an Orimulsionsample, was incubated for up to 120 days with sedimentscollected at a petroleum-impacted site in Tampa Bay,Florida. Biodegradation conditions were optimized byincreasing bitumen surface area, continuous agitation ona shaker apparatus, use of a complete growth medium, andmaintenance at 37 °C. Aerobic degradation conditionswere promoted by maintaining sediment contact with thelaboratory atmosphere. Bitumen recovered in solventextracts when compared to autoclaved controls decreasedby up to 40% during the first 56 days. There was nodetectable change after this. Molasses addition and useof a culture enriched from the sediments did not change theextent or rate of decrease in bitumen recovery. Chemicalfractionation of bitumen control and degraded bitumenshowed that aromatic and aliphatic fractions were depletedby ≈50%. Accumulation of polars was observed; however,the apparent increase was relatively small when comparedto the mass loss of the other fractions. Selected biomarkerratios were not affected by incubation indicating theirutility for fingerprinting the source bitumen in environmentalsamples. PAH distribution in the aromatic fraction favoredthe higher alkyl-homologues with the relative degree ofalkylation increasing as the mass of bitumen recovereddecreased with degradation. The study showed that up to40% of the bitumen was bioaccessible and that bioremediation may be a treatment option for sediments contaminatedwith bitumen by an Orimulsion spill.
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