EFFECT OF VEGETATION ON BIOREMEDIATION OF
WEATHERED PETROLEUM HYDROCARBONS IN SOIL
James Brown*
Lockheed Martin/REAC
2890 Woodbridge Avenue
Bldg. 209 Annex
Edison, NJ 08837
Voice: 732-494-4060
Fax: 732-494-4021
E-mail: James.L.Brown@lmco.com
Harry Allen
U.S. EPA
Edison, NJ
A growth chamber study was conducted to determine whether bioremediation of petroleum hydrocarbons in soil is enhanced in the plant rhizosphere. Results from the first six months of a 12-month study will be presented. Soil was obtained from an abandoned Wyoming refinery and contained 1.7% weathered TPH. In Stage I of the study, 15 cool- and warm-season grasses were screened for TPH tolerance. Plants were grown in soil with 1% and 2% TPH, and in uncontaminated background soil. Plant screening criteria were: 1) germination and growth in 2% TPH soil; 2) tolerance of moderate to high salinity; and 3) 70% of the growth obtained in uncontaminated soil. Six cool-season grasses and one warm-season grass met the criteria, and were selected for the Stage II, 12-month study. Study periods were divided into two six-month increments for ease of temperature control. Cool-season grasses were grown from October through March at an average temperature of 15 degrees C. Warm-season grasses were grown from April through September at an average temperature of 27 degrees C. The statistical design utilized the following parameters: α = 0.05; β = 0.10; d = 10%; n = 7, where α and β are Type I and Type II errors, respectively, d is the desired treatment effect, and n is number of replicates. After six months, there were no significant differences in TPH losses between any of the vegetated and non-vegetated treatments. There was also no significant effect of increasing temperature from 15 to 27 degrees C on TPH losses in non-vegetated soil. Soil samples will again be analyzed after 12 months to determine whether additional time is a prerequisite for enhanced treatment of TPH within the rhizosphere.