Phytoremediation of Petroleum Hydrocarbons
Assessment of phytoremediation as an in-situ technique for cleaning petroleum-contaminated sites
What is the purpose of this project?
Phytoremediation, the use of plants for the in situ treatment of contaminated soils, is essentially ecological engineering which capitalizes on the naturally occurring synergistic relationships among plants, microorganisms, and the environment that have evolved over millions of years. Phytoremediation takes advantage of the fact that plants have extensive rooting systems which explore large volumes of soil, support larger bacterial populations in the rhizosphere (the region immediately surrounding the root) than in the surrounding bulk soil, and produce exudates which can directly affect the activity of the rhizobacterial populations. Though generally considered a long-term remediation process limited to soils where the contamination is shallow and occurs at low to medium concentrations, phytoremediation holds significant promise for the cost-effective cleanup of certain types of hazardous wastes including gasoline, diesel fuel, and petroleum hydrocarbons. Given the high cost of traditional cleanup methods, phytoremediation may provide an ideal means of initiating and/or accelerating cleanups at hundreds of petroleum-contaminated sites in western Canada.
The overall objective of this project is to evaluate the effectiveness of phytoremediation in reducing hydrocarbon concentrations in soils contaminated with historical, or weathered, oil products.
How is the project being conducted?
The specific objectives of the project are to:
· conduct a literature review to assess current phytoremediation techniques and produce a searchable database with an inventory of plants that can reduce hydrocarbon levels in soils and wetlands
· conduct botanical surveys of weathered hydrocarbon-contaminated sites in Alberta and Saskatchewan to identify plants with phytoremediation potential
· screen the phytoremediation potential of selected candidate plant species
· conduct growth chamber studies to optimize plant growth/phytoremediation variables, elucidate degradation mechanisms, and develop field assessment protocols
· conduct field trials of selected phytoremediation technologies.
What are the results?
The literature review and botanical surveys in Alberta were completed in December 1999 and reports of those results published on the Department of Soil Science, University of Saskatchewan web site (http://www.ag.usask.ca/departments/scsr/department/research/index.html) and in CD format. The database (PhytoPet©) was completed in spring 2000, listing 61 plants with a demonstrated potential to phytoremediate or tolerate petroleum hydrocarbons. The PhytoPet© database (ver. 2.1) is currently available in CD format; a web-based version of the database (ver. 3.0) is currently under development.
Potential phytoremediation plants were chosen based on the following criteria: plants with a demonstrated ability to phytoremediate or, at the very least, tolerate petroleum hydrocarbons (11 plant species adapted to the Prairie and Boreal Plains Ecozones were identified from the PhytoPet© database); plant species identified during the 1999 botanical surveys (70 plant species were catalogued at the contaminated sites); and plant species used for native prairie restoration projects (15 species chosen that are commonly recommended for use in western Canada). Information on suggested seed treatments and availability of seed was used to refine the selection of suitable candidate plant species. To date, 42 species have been screened. These include: 13 native grasses, 7 native legumes, 15 native non-leguminous forbs, 4 exotic grasses, and 3 exotic legumes.
What happens next?
Final plant screenings and preliminary growth chamber studies will be conducted in the coming year. In addition, field work will be conducted at two sites. These latter studies will be undertaken to field test plant species chosen during the screening phase of the study. Site selection is still underway; though partial funding for this phase of the study is currently in place, additional funding will be required.
Research collaborators
Drs. James Germida and Richard Farrell (Co-PIs), Department of Soil Science, University of Saskatchewan
Drs. J. Diane Knight & Ken Van Rees, Department of Soil Science, University of Saskatchewan
Research collaborators (continued)
Diana Robson (Ph.D. student), Julie Roy (M.Sc. student), Adam Gillespie (M.Sc. student), Cindy Wall (M.Sc. student) – Department of Soil Science, University of Saskatchewan
Drs. Louise Nelson & Russ Hynes, Department of Applied Microbiology, University of Saskatchewan
Dr. Sandra Blenkinsopp, Environment Canada
Dr. Stuart Lunn, Imperial Oil Resources
Project Funding
Funding for this project has been provided by the Natural Sciences and Engineering Research Council (NSERC); Environment Canada; the Canadian Association of Petroleum Producers (CAPP) Environmental Research Advisory Council (ERAC); Program of Energy Research and Development (PERD); the Saskatchewan Agriculture & Food Strategic Research Program in Soil Biology & Conservation; Federated Co-Operatives, Ltd.; Veco Canada Ltd., Alliance group; Amoco Canada Petroleum Co. Ltd.; and Imperial Oil Resources (IOR).