Enhanced degradation of the Alaskan weathered crude oil alkane and aromatic hydrocarbons by indigenous microbiota through application of nutrients

Bench-scale biodegradability studies of the alaskan weathered crude oil were undertaken as part of the bioremediation project for the shorelines of Prince William Sound, Alaska, contaminated by the Exxon oil spill. The purpose of the studies was to evaluate the capability of the indigenous microbial consortium of the sea water and island beach areas, to biodegrade the weathered crude oil alkane hydrocarbon and polynuclear aromatic (PAH) constituents in batch-type respirometric reactors and shaker flask systems. Biodegradation studies incorporated the use of INIPOL EAP22 and water soluble nitrogen and phosphorus containing solution (OECD) as the fertilizer nutrient source. In the respirometric studies, the unpolluted beach material in seawater was piked with 1,000, 300, and 100 mg/L of weathered crude oil and with INIPOL at 5% of oil weight or with OECD stock solution concentrates. The contents were brought up to 1,000 mL with seawater. Unpolluted beach material spiked with 10,000, 3,000, and 1,000 mg/L of weathered crude oil and with either INIPOL at 5% of oil weight or with OECD inorganic salts in 1,000 mL of seawater were used in shaker flask microcosm studies. Temperature of incubation in both studies was 15 C, and culture systems were incubated in darkness. Cumulative oxygen uptake data, growth data and the GC/MS analysis data demonstrate almost complete utilization of the alkane hydrocarbon constituents in the presence of INIPOL fertilizer and OECD synthetic medium, and significant biodegradation of the PAH constituents after 6 weeks of incubation. Control experiments without INIPOL or OECD nutrients demonstrated absence of biodegradative activity