enhanced biodegradation of a light crude oil in ... - IOSC Proceedings

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ABSTRACT: Laboratory tests conducted at 3° C and 20° C indicate that biodegradation of a light crude oil (condensate) by indigenous micro flora of sandy ...
ENHANCED BIODEGRADATION OF A LIGHT CRUDE OIL IN SANDY BEACHES Kenneth Lee and Eric M. Levy Department of Fisheries and Oceans Bedford Institute of Oceanography P.O. Box 1006 Dartmouth, Nova Scotia B2Y 4A2, Canada Oil-degrading microorganisms are ubiquitous and can metabolize a wide range of oil components. 617 Biodegradation plays a principal role in the natural weathering of petroleum in the marine environment. 18 Although the potential capability of indigenous microflora to degrade oil is a function of the physical and chemical properties of the sea water and oil, the environmental conditions, and the biota themselves, it is generally accepted that availability of nutrients is probably the most common limiting factor.4 Experimental studies have shown that fertilization with nitrogen and phosphorus offers great promise as a countermeasure for combating oil spills in the marine environment, 3 ' 27 and the optimum ratios among carbon, nitrogen, and phosphorus have been defined in the laboratory. 10 In the field, however, water-soluble nutrients are rapidly diluted into the surrounding waters and thus removed from the oil-water interface where the biodegradation occurs. To overcome this problem, oleophilic nutrients intended to maintain optimum concentrations of nitrogen and phosphorus at the oil-water interface have been developed, and the results of preliminary tests with water-soluble nutrients encapsulated in paraffin4'19 and with microemulsions of water-soluble nutrients in a lipophilic phase 22 ' 26 have been very encouraging. While oil-degrading microorganisms with constitutive enzyme systems have been isolated, most use adaptive systems, which appear only after a period of contact with hydrocarbons. During this time, some toxic fractions of the oil may be lost, but physical-chemical reactions may also produce components that are highly toxic or refractory. Seeding with specific strains of oil-degrading bacteria immediately following an oil spill may supply degradation capability during this induction period. This study combines laboratory and field experiments to evaluate nutrient enrichment and microbial seeding as a means of enhancing the biodegradation of a light crude oil (SSC) within the intertidal sediments of a low-energy sand beach in Atlantic Canada.

ABSTRACT: Laboratory tests conducted at 3° C and 20° C indicate that biodegradation of a light crude oil (condensate) by indigenous micro flora of sandy beach environments can be enhanced by the addition of an oleophilic nutrient. However, field trials conducted over a 204 day period in the intertidal zone of a sandy beach in Atlantic Canada demonstrated an acute toxic response by natural microflora to the (