CHARACTERIZATION AND BIOTREATABILITY OF PETROLEUM-CONTAMINATED SOILS IN A CORAL ATOLL IN THE PACIFIC-OCEAN

On Kwajalein Island in the Republic of the Marshall Islands, studies w ere conducted to characterize subsurface petroleum contamination and a ssess the potential for bioremediation of contaminated soils and sedim ents. Because of its remote location and problems with shipment of sam ple materials off-site, characterization and biotreatability studies w ere conducted on the Island during a 12-d site visit. Analyses were ma de of soil contamination levels, physical/chemical properties, and mic robial densities, while microcosm studies were made of biodegradation potential. It was found that the coral-derived sands on Kwajalein Isla nd were alkaline (e.g., pH > 8) and deficient in nutrients (e.g., low N, P). Microorganisms were abundant (103-107 org.g(-1)) and included a ppreciable hydrocarbon degraders. Diesel fuel contamination ranged fro m below detection limits to nearly 9000 mg TPH kg(-1), with the highes t levels in the capillary fringe and upper saturated zone of a freshwa ter lens beneath the Island. Biodegradation of fresh diesel fuel added to clean soil occurred very slowly (e.g., < 0.5 mg TPH kg(-1) d(-1)). Biodegradation of diesel fuel added to previously contaminated soils that were also supplemented with nutrients, proceeded at higher but st ill relatively low rates (e.g., < 2 mg TPH kg(-1) d(-1)). It was concl uded that bioremediation of diesel fuel contaminated soils by indigeno us organisms was feasible on Kwajalein Island, although degradation ra tes were very low, with some enhancement possible by the addition of n utrients.