(519f) A Five-Year Field Study to Evaluate Phytoremediation of a Crude Oil-Contaminated Soil

Phytoremediation can be a cost-effective and low-maintenance means of remediating crude oil-contaminated soil. The objective of the field study was to evaluate the effects of vegetation establishment and fertilizer additions on remediation of crude oil-contaminated soil. Four replications of the following treatments were used: non-fertilized vegetation-free control; ryegrass - fescue mixture + fertilizer; or bermudagrass - fescue mixture + fertilizer. Vegetation was successfully established at the site and samples were collected a total of 10 times over a 5-yr period. Soil chemical and biological properties were analyzed and the initial GC/FID total petroleum hydrocarbon (TPH) concentration of 9,175 mg/kg was reduced to a range of 3,000 to 8,000 mg/kg after 57 months. Results indicated bacteria levels were greater in the vegetated + fertilized plots than in the control. Mean shoot biomass yields after 42 months were 110 and 85 g/m2 for the bermudagrass - fescue mixture + fertilizer and ryegrass - fescue mixture + fertilizer, respectively. Mean root biomass after 42 months were 1325 and 5246 g/m3 for the bermudagrass - fescue mixture + fertilizer and ryegrass - fescue mixture + fertilizer, respectively. Bacterial and fungal numbers increased in response to vegetation establishment and fertilizer addition during phytoremediation of the crude oil-contaminated site.