Habitat recovery in an oil-contaminated salt marsh following biorestoration treatments

Abstract

Wetlands are among the most sensitive of habitats to oil spills. A field experiment was conducted on a salt marsh in Atlantic Canada to determine the significance of bioremediation by nutrient enrichment in enhancing wetland restoration. Six experimental treatments were monitored: (1) unoiled control (2) unoiled control + nutrients, (3) oil with no treatment (natural attenuation), (4) oil + nutrients, (5) oil + nutrients with plants cut back, (6) oil + nutrients with disking (tilling) to enrich oxygen penetration. Remediation success was quantified by determining changes in the composition and concentration of the residual oil, plant recovery and reduction in sediment toxicity. The experimental results advocate natural attenuation as the clean-up strategy for the ecotype under study. Within the untreated plots, significant recovery of the predominant plant species within the marsh (Spartina alterniflora) was observed after 20 weeks and approximately 90% of the resolved n-alkanes and 70% of the parent and alkyl-substituted poly-aromatic hydrocarbons (PAH) were biodegraded.