A Field Demonstration of the Efficacy of Bioremediation to Treat Oiled Shorelines Following the Sea Empress Incident

Abstract

Bioremediation was investigated as a method of treating a mixture of Forties Crude Oil and Heavy Fuel Oil stranded on Bullwell Bay, Milford Haven, UK after the grounding of the Sea Empress in 1996. A randomised block design in triplicate was used to test the efficacy of two bioremediation treatments: a weekly application of mineral nutrients dissolved in seawater and a single application of a slow-release fertilizer. Each treatment supplied an equivalent amount of nitrogen and phosphorus. Concentrations of residual hydrocarbons normalised to the biomarker 17α(H),21β(H)-hopane showed that after two months the oil was significantly (p<0.001) more biodegraded in the treated plots than in the controls. On average, the oil in the nutrient amended plots was 37% more degraded than that found in the controls. There was no evidence that the bioremediation treatments increased the toxicity of the oiled sediment. The results confirm that bioremediation can be used to treat a mixture of crude and heavy fuel oil on a pebble beach. In particular, the data suggest that the application of a slow-release fertilizer alone may be a cost-effective method of treating low-energy, contaminated shorelines after a spill incident.