Ecological Engineering 10 (1998) 263 – 274 The combined effects of phytoremediation and biostimulation in enhancing habitat restoration and oil degradation of petroleum contaminated wetlands Qianxin Lin *, Irving A. Mendelssohn Wetland Biogeochemistry Institute, Center for Coastal, Energy, and Enironmental Resources, Louisiana State Uniersity, Baton Rouge, LA 70803, USA Received 24 July 1997; received in revised form 3 February 1998; accepted 10 February 1998 Abstract The combined effects of biostimulation and phytoremediation as a means of post-oil spill habitat restoration and enhancement of oil degradation in the soil were evaluated. Marsh sods of Spartina alterniflora and 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 dosages of 8 l m -2 in the growing season following oil application. Two years after application of the oil, S. alterniflora and S. patens individuals were transplanted into the oiled and unoiled sods. Fertilizer was applied 1 and 7 months after transplantation. Application of the fertilizer significantly increased biomass of the transplants within 6 months and regrowth biomass of the transplants 1 year after transplantation for both plant species. The residual oil in the soil did not significantly affect the biomass of the S. patens transplants compared with that in the no oil treatment, except at the highest oil level. However, regrowth biomass of the S. alterniflora transplants treated with fertilizer was significantly higher at all oil levels up to 250 mg g -1 than in the unoiled treatment, with or without fertilizer. The oil degradation rate in the soil was significantly enhanced by the application of fertilizer in conjunction with the presence of transplants. These results suggest that vegetative transplantation, when implemented with fertilization, can simultaneously restore oil contaminated wetlands and accelerate oil degradation in the soil. © 1998 Elsevier Science B.V. All rights reserved. Keywords: Biostimulation; Marshes; Oil spills; Phytoremediation; Spartina ; Restoration * Corresponding author. Tel.: +1 504 3888810; fax: +1 504 3886423. 0925-8574/98/$19.00 © 1998 Elsevier Science B.V. All rights reserved. PII S0925-8574(98)00015-9