ENHANCED BIODEGRADATION OF A LIGHT CRUDE OIL IN SANDY BEACHES

Abstract

ABSTRACT Laboratory tests conducted at 3° C and 20° C indicate that biodegradation of a light crude oil (condensate) by indigenous microflora 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 “unweathered” condensate, and bacterial growth in the oiled sediments did not increase until the concentration of toxic low molecular weight aromatic compounds had been reduced by evaporation and/or dissolution. Chemical and bacteriological data suggest that this increase in bacterial numbers within the oiled enclosures may not be a direct consequence of condensate utilization. Although biodegradation of condensate stranded in beaches may be limited by the availability of nutrients, a single application of an oleophilic nutrient immediately following the addition of the crude oil did not enhance biodegradation. While limited biodegradation of the oil was observed in sediments seeded with bacteria, evidence shows that such allochthonous microorganisms were not sustained in the natural environment. This work suggests that the most promising approach to enhancing the biodegradation of oil stranded in sandy beach environments is through periodic replenishment of nutrients after the indigenous microflora have adapted to the contaminated sediments.