Assessment of Phytoremediation as an In-Situ Technique for Cleaning Oil-Contaminated Sites

This document was developed as a literature review and technology assessment of phytoremediation and its alternatives. As such, the stakeholders do not endorse the use of any specific technology, nor do they assume any liabilities with respect to the use of, or damages resulting from the use of, any information, apparatus, method, or process discussed in this document. Mention of trade names or commercial products does not constitute endorsement or recommendation of use. Phytoremediation, the use of plants and their associated microorganisms for the in situ treatment of contaminated soils, is a steadily emerging technology with potential for the effective and inexpensive cleanup of a broad range of organic and inorganic wastes. Based on a review of the relevant literature, we provide examples of the phytoremediation of petroleum hydrocarbons and discuss the key mechanisms as well as the special considerations involved in petrochemical phytoremediation. The benefits, limitations, and costs of phytoremediation compared to alternative approaches – including natural attenuation, engineering and bioremediation – also are discussed. Initial indications are that phytoremediation is effective at degrading and containing petroleum hydrocarbons in soil as well as transferring these compounds from soil to the atmosphere. The literature suggests that the degradation of petroleum hydrocarbons by microorganisms in the rhizosphere of plants is the primary loss mechanism for these compounds. Based on available information, it appears that phytoremediation of petroleum hydrocarbons is quicker but more expensive than natural attenuation and, conversely, slower but less expensive than most engineering techniques and traditional bioremediation methods. Preliminary screenings indicate that there are native and introduced plants that could be used in phytoremediation efforts in the Prairie and Boreal Plains Ecozones. Little published information exists, however, on the application of phytoremediation to oil-contaminated sites in Canada. Likewise, only a handful of studies examine in detail the specific mechanisms of petrochemical phytoremediation.