Bioremediation: Waxy crude oils stranded on low-energy shorelines

Abstract

The degradation of a wary crude oil (Terra Nova) spilled on sand beach and salt marsh environments in Nova Scotia was monitored over a seven-month period. In the sand beach environment, low concentrations of stranded oil (0.3 percent by volume) were degraded in a matter of days by the indigenous biota, while higher concentrations (3 percent) were much more persistent (components as light as n-C11 remained after six months). In contrast, similar concentrations of oil were found to be extremely resistant to biodegradation in the salt marsh. Our results suggest that cleanup of waxy crude oils at low concentrations in sand beaches should be left to nature, since natural biodegradative processes occur rapidly. At higher oil concentrations, however, nutrient enrichment with agricultural fertilizers was found to be an effective countermeasure. While biodegradation of oil stranded in salt marsh environments is generally limited by oxygen availability, nutrient enrichment may be an effective countermeasure to treat low concentrations of waxy crude oil in salt marshes, provided the oil does not penetrate beneath the aerobic surface layer.