Citation:

VENOSA, A. D. BIOSTIMULATION CAN SOMETIMES ENHANCE ENVIRONMENTAL CLEANUP - An Editorial Viewpoint on Bioremediation. Second Edition, Chapter 4, J.H. Withgott, S. Brennan (ed.), ENVIRONMENT - The Science Behind the Stories. Pearson Education, Inc., San Francisco, CA, , 112, (2007).

Impact/Purpose:

To determine if Biostimulation can be used to restore environments contaminated with chemicals.

Description:

The Exxon Valdex oil spill, which led to the enactment of the Oil Pollution Act of 1990, gave rise to the largest bioremediation field trial ever attempted. A research sutdy was conducted by EPA in 1989 and 1990 to develop data to support the recommendation to go forward with a full-scale cleanup. Unfortunately, the data generated were equivocal and did not provide sufficient evidence to prove the success of the treatment. Data generated in later EPA-funded field studies provided sufficient, statistically sound evidence that biostimulation of indigenous microorganisms can accelerate the disappearance of hydrocarbons at a spill site. The reason why the original research study was equivocal was that its experimental design did not provide sufficient replication or randomization of plots to allow for the calculation of experimental error or to account for the high variability of oil contamination on the beaches. A later field study in Delaware did provide the unequivocal evidence needed (Venosa et al., 1996). Two other studies, both done on Canadian wetlands, showed that biostimulation may not always be appropriate (Venosa and Zhu, 2003; Venosa et al., 2002). One needs to determine the background levels of nutrients already present and make sure the affected environment is aerobic in nature. Only if nutrients are limiting in concentration and dissolved oxygen in the pore space are high enough to support microbial growth on the hydrocarbons is biostimulation appropriate. EPA published two guidance documents on bioremediation on marine shorelines, freshwater wetlands, and salt marshes. Another report was published discussing the use of commercial bioremediation agents for use in biostimulation (nutrient addition) and bioaugmentation (microorganism addition). The common link to these three reports is http://www.epa.gov/oilspill/science.htm. Biostimulation plays a key role in environmental cleanup of oil spills. It is a tool to be seriously considered when contemplating how to restore a contaminated environment.

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