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Summary: phytoremediation
Review: One of the technologies being tested in the AATDF program is phytoremediation, or vegetation-enhanced bioremediation, of fuel-contaminated soil. Traditional biological land treatment of fuel-contaminated soil can often result in final concentrations that do not meet clean-up criteria. One potential approach for the long-term management of fuel-contaminated soils is the establishment of vegetation, because the presence of vegetation may enhance the biodegradation of contaminants. Vegetation may directly aid biodegradation by accumulating, metabolizing, or volatilizing contaminants, as in the example of vegetation that hyper-accumulates metals. Vegetation may indirectly enhance biodegradation of contaminants through the action of rhizosphere microflora. Rhizosphere microflora are supported by exudates, such as carbohydrates and amino acids, released through plant roots and decaying vegetation. High microbial biomass and high microbial activity are associated with the rhizosphere, which may increase the biodegradation of organic contaminants relative to non-rhizosphere soil microflora. Phytoremediation may be especially suitable for shallow, contaminated soils, especially if it is used as a long-term, low-maintenance, low-cost remedial method. Some investigators, however, believe the beneficial effects of phytoremediation have been over-stated. The effect of vegetation on biodegradation might range from enhancing biodegradation to having no effect or even negative impacts. There is a dearth of quantitative field data on the effectiveness of phytoremediation, especially relative to actively-managed land treatment of contaminated soils. For these reasons, DOD/AATDF decided to fund a field test of phytoremediation. The data from this field test should supply information about the effectiveness of vegetation for the remediation of diesel-contaminated soils. The technology may provide a cost-effective alternative for soils management for the DOD.
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