Testing the efficacy of oil spill bioremediation products

Ten bioremediation products were tested in laboratory respirometers for their ability to enhance the biodegradation of artificially weathered Alaska North Slope crude oil compared to natural populations supplied with mineral nutrients. The sea water used was natural sea water obtained from the Gulf of Mexico near Gulf Breeze, Florida. All products were tested in triplicate in closed laboratory flasks connected to an instrument able to track and record cumulative oxygen uptake continuously over time. Triplicate flasks were sacrificed periodically, the contents extracted with hexane, and the oil components quantified by gas chromatography/mass spectrometry (GC/MS). Correlations were made between the decline in aliphatic and aromatic analytes and the net oxygen uptake observed in each flask. From these correlations, the median time needed to consume enough oxygen to effect a 6O percent decline in the total resolved analytes was computed for each product, and this time was compared statistically to the time needed by the natural populations in the source sea water to effect the same removal. Using this approach, five of the ten products were found to enhance biotransformation of the crude oil analytes. When the analysis was repeated for the aromatic constituents only, using a target removal of only 25 percent, only two of the ten products gave shorter response times than the nutrient-supplemented sea water