THE COMBINED EFFECTS OF PHYTOREMEDIATION AND BIOSTIMULATION IN ENHANCING HABITAT RESTORATION AND OIL DEGRADATION OF PETROLEUM-CONTAMINATED WETLANDS

The combined effects of biostimulation and phytoremediation as a means of post-oil spill habitat restoration and enhancement of oil degradat ion in the soil were evaluated. Marsh sods of Spartina alterniflora an d Spartina patens were dosed with 0, 4, 8, 16 and 24 l m(-2) of south Louisiana crude oil in the greenhouse. Plants were killed at oil dosag es of 8 l m(-2) in the growing season following oil application. Two y ears after application of the oil, S. alterniflora and S. patens indiv iduals were transplanted into the oiled and unoiled sods. Fertilizer w as applied 1 and 7 months after transplantation. Application of the fe rtilizer significantly increased biomass of the transplants within 6 m onths and regrowth biomass of the transplants 1 year after transplanta tion for both plant species. The residual oil in the soil did not sign ificantly affect the biomass of the S. patens transplants compared wit h that in the no oil treatment, except at the highest oil level. Howev er, regrowth biomass of the S. alterniflora transplants treated with f ertilizer was significantly higher at all oil levels up to 250 mg g(-1 ) than in the unoiled treatment, with or without fertilizer. The oil d egradation rate in the soil was significantly enhanced by the applicat ion of fertilizer in conjunction with the presence of transplants. The se results suggest that vegetative transplantation, when implemented w ith fertilization, can simultaneously restore oil contaminated wetland s and accelerate oil degradation in the soil. (C) 1998 Elsevier Scienc e B.V. All rights reserved.