EVALUATION OF TOLERANCE LIMITS FOR RESTORATION AND PHYTOREMEDIATION WITH SPARTINA ALTERNIFLORA IN CRUDE OIL-CONTAMINATED COASTAL SALT MARSHES

摘要

Information and knowledge about the oil tolerance of native coastal plants are limited, but are essential for restoring and remediating oil impacted habitats. Spartina alterniflora is the dominant native salt marsh plant species along the Northern Gulf of Mexico and the Atlantic coast; the presence of this species is important to sustain healthy coastal salt marshes. The crude oil tolerance limits of S. alterniflora and its capacity to phytoremediate South Louisiana crude (SLC) oil in marsh sediments were investigated in a greenhouse. Spartina alterniflora was transplanted into marsh sediments contaminated with SLC at concentrations of 0, 40, 80, 160, 320, 640 and 800 mg/g. Plant photo synthetic rate, stem density, shoot height, aboveground biomass and belowground bio-mass were analyzed periodically during a one-year plant growth cycle to determine the oil tolerance limits of S. alterniflora. Most plant parameters were significantly lower at 320 and 640 mglg of SLC oil in the soil compared to the control. No plants survived at the 800 mglg SLC oil dosage. The tolerance limits of Spartina alterniflora were estimated between 320 mglg and 640 mglg of SLC oil in the soil. Furthermore, phytoremediation with S. alterniflora enhanced oil degradation; residual concentrations of total petroleum hydrocarbons in the phytoremediation treatment with S. alterniflora were significantly lower than those in oiled, unvegetated sediments for both the surface and subsurface soil at the 40 and 160 mglg oil dosages one year after treatment. The current study shows the promise of using coastal marsh vegetation for restoring crude oil-impacted coastal wetlands and enhancing oil spill cleanup.