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LITERATURE REVIEW ON THE USE OF COMMERCIAL BIOREMEDIATION AGENTS FOR CLEAN-UP OF OIL-CONTAMINATED ESTUARINE ENVIRONMENTS
Zhu, X., A D. Venosa*, AND M. T. Suidan. LITERATURE REVIEW ON THE USE OF COMMERCIAL BIOREMEDIATION AGENTS FOR CLEAN-UP OF OIL-CONTAMINATED ESTUARINE ENVIRONMENTS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-04/075 (NTIS PB2004-106188), 2004.
The objective of this document is to conduct a comprehensive review of the use of commercial bioremediation products treating oil spills in all environments, Literature assessed includes peer-reviewed articles, company reports, government reports, and reports by cleanup contractors engaged in responses to oil spills. The scope of this review is in the general context of estuarine environments. However, marine shorelines, terrestrial environments, freshwaters, and wetlands are frequent candidates for bioremediation of spilled oil, and these ecosystems are also included in the review for completeness. The review is useful for oil spill responders (e.g., on-scene coordinators and response contractors) to better understand the feasibility of bioremediation technology and as an aid in selecting bioremediation products.
The overall conclusions reached by this review are as follows. First, according to the peer-reviewed literature, bioaugmentation appears to have little benefit for the treatment of spilled oil in an open environment. Microbial addition has not been shown to work better than nutrient addition alone in many field trials, However, case studies provided by vendors seem to suggest that application of bioaugmentation products could still have some potential in the treatment of specific oil components, isolated spills in confined areas, or certain environments where oil-degrading microorganisms are deficient. Unfortunately, the evidence for such a conclusion is not strong and in most, if not all, cases is scientifically deficient.
Biostimulation has been proven to be a promising tool to treat certain aerobic oil-contaminated shorelines. One of the key factors for the success of oil biostimulation is to maintain an optimal nutrient level in the interstitial pore water. In general, commercial oleophilic nutrient products have not shown clear advantages over common agricultural fertilizers in stimulating oil biodegradation. Effects of nutrients are also highly site-specific. For example, the availability of oxygen rather than nutrients is often the limiting factor in wetland environments, where addition of nutrient products has not been successful in enhancing oil biodegradation.
The extreme uncertainty associated with the efficacy ofbioremediation agents is due in large part to the poorly designed field tests that have been conducted to demonstrate efficacy, Much of the reported literature lacked proper controls and treatment randomization and replication, or the data were incorrectly analyzed. If there is any hope for advancement of commercial bioremediation for the environments described in this report, especially estuaries, experiments based on sound scientific principles are needed.