GUIDELINES FOR THE BIOREMEDIATION OF MARINE SHORELINES AND FRESHWATER WETLANDS Prepared by: 1Xueqing Zhu, 2Albert D. Venosa, 1Makram T. Suidan, and 3Kenneth Lee 1University of Cincinnati Department of Civil and Environmental Engineering Cincinnati, OH 45221 2U.S. Environmental Protection Agency National Risk Management Research Laboratory Cincinnati, OH 45268 3Department of Fisheries and Oceans-Canada Bedford Institute of Oceanography Marine Environmental Sciences Division Dartmouth, Nova Scotia B2Y 4A2 September, 2001 U.S. Environmental Protection Agency Office of Research and Development National Risk Management Research Laboratory Land Remediation and Pollution Control Division 26 W. Martin Luther King Drive Cincinnati, OH 45268 Acknowledgments The preparation of this guidance document was performed under the direction of Albert D. Venosa of EPA’s Treatment and Destruction Branch, Land Remediation and Pollution Control Division, National Risk Management Research Laboratory, Cincinnati, OH. The report was prepared under EPA Contract 68-C7-0057, Task Order 23 by the University of Cincinnati with the assistance of the Department of Fisheries and Oceans-Canada. Disclaimer This report has been reviewed and approved for publication by the Land Remediation and Pollution Control Division, National Risk Management Research Laboratory of the U.S. Environmental Protection Agency. Mention of company names, trade names, or commercial products does not constitute EPA endorsement or recommendations for use. Further Information For further information, contact: Albert D. Venosa, Ph.D. U.S. EPA 26 W. Martin Luther King Drive Cincinnati, OH 45268 Tel: 513-569-7668 Fax: 513-569-7105 Email: [email protected] EXECUTIVE SUMMARY The objective of this document is to present a detailed technical guidance document for use by spill responders for the bioremediation of marine shorelines and freshwater wetlands contaminated with oil and oil products. Technical personnel who are responsible for designing and operating field bioremediation processes as well as consultants and equipment manufacturers will also find it useful. This manual presents a rational approach for the design of bioremediation processes pertinent to cleanup of oil-contaminated marine shorelines and freshwater wetlands. This document evaluates current practices and state-of-the-art research results pertaining to bioremediation of hydrocarbon contamination relative to types and amounts of amendments used, frequency of application, assessment of the extent of bioremediation, sampling, and analysis. The scope of the document is limited to marine shorelines and freshwater wetlands because of definitive results from recently completed, EPA-sponsored field studies. The final product is presented in a report form that is understandable by responders, on-scene coordinators, and remediation specialists. This report includes a thorough review and critique of the literature and theories pertinent to oil biodegradation, nutrient dynamics in shorelines, and analytical chemistry of oil and remediation nutrients. A planning approach to site identification, evaluation, and selection along with information on field investigations is also presented. The manual includes examples of bioremediation options and case studies of bioremediation applied to marine shorelines and freshwater wetland environments. The contents of this document are arranged in a logical sequence first to provide basic information for the evaluation of bioremediation as a spill response option followed by guidelines for application that includes methods to monitor its effectiveness. Thus, Chapter 1 presents an overall introduction and background discussion of bioremediation including occurrence of oil spills, response methodologies, and a summary of the scope, organization, and objective of the manual. Chapter 2 covers the basic information about oil, shorelines, mechanisms of oil biodegradation, and a state-of-the-art review of controlled laboratory experiments and field trials of oil biodegradation and nutrient dynamics in shoreline environments. For additional background information, Chapter 3 provides a more thorough review and critique of current analytical methods used to monitor and verify oil spill bioremediation success. Chapter 4 summarizes major biostimulatory and bioaugmenting amendment methods and their application strategies. Chapter 5 is the heart of the document and presents the actual guidelines for designing, planning, and implementing oil bioremediation in the field, including site characterization, evaluation of appropriate bioremediation technologies, and the selection of the most appropriate technology for a specific site. Finally, Chapter 6 provides guidelines for assessment and interpretation of field results and provides help in assessing endpoints of bioremediation (i.e., when treatment is considered complete). The overall conclusions reached by the guidance manual are as follows. First, with respect to marine sandy shorelines, natural attenuation may be appropriate if background nutrient concentrations were high enough that intrinsic biodegradation would take place at close to the expected maximum rate. The Delaware study proved this clearly. Certainly in nutrient-limited places like Prince William Sound, Alaska, nutrient addition should accelerate cleanup rates many-fold. However, the decision to use the natural attenuation approach may be tempered by the need to protect a certain habitat or vital resource from the impact of oil. For example, using Delaware as the model, every spring season, horseshoe crabs migrate to the shoreline of Delaware for their annual mating season. Millions of eggs are laid and buried a few mm below the surface of the sand. Migrating birds making their way from South America to Arctic Canada fly by this area and feed upon these eggs to provide energy to continue their long flight. If an oil spill occurred in February or March, it would certainly be appropriate to institute bioremediation to accelerate the disappearance of the oil prior to the horseshoe crab mating season despite the expected high natural attenuation rate. So, even in the case where background nutrients are high enough to support rapid biodegradation, addition of more nutrients would help protect such a vital resource. If the spill occurred during the summer, and no vital natural resources were threatened by the spill, then reliance on natural attenuation might be the wisest course of action. Of course, removal of free product and high concentrations of oil should still be conducted by conventional means even if a no bioremediation action is warranted by the circumstances. With respect to freshwater wetlands, the St. Lawrence River study demonstrated that, if significant penetration of oil takes place into the subsurface, biodegradation would take place very slowly and ineffectively. This is because of the anaerobic conditions that quickly occur in these types of saturated environments, and anaerobic biodegradation of petroleum oils is much slower and less complete than under aerobic conditions. One of the objectives of the St. Lawrence River experimental design was to determine the amenability of wetlands to biodegradation when oil has penetrated into the sediment. The oil was artificially raked into the sediment to mimic such an occurrence. Consequently, no significant treatment effects were observed because all the nutrients in the world would not stimulate biodegradation if oxygen were the primary limiting material. If penetration did not take place beyond a few mm, then bioremediation might be an appropriate cleanup technology, since more oxygen would be available near the surface. It is clear that whatever oxygen gets transported to the root zone by the plants is only sufficient to support plant growth and insufficient to support the rhizosphere microorganisms to degrade contaminating oil. However, if ecosystem restoration is the primary goal rather than oil cleanup, the St. Lawrence River study strongly suggested that nutrient addition would accelerate and greatly enhance restoration of the site. Abundant plant growth took place in the nutrient-treated plots despite the lack of oil disappearance from the extra nutrients. Furthermore, the stimulation lasted more than one growing season even though nutrients were never added after the first year. Clearly, the plants took up and stored the extra nitrogen for use in subsequent growing seasons, so restoration of the site was abundantly evident in a few short months. Thus, in conclusion, the decision to bioremediate a site is dependent on cleanup, restoration, and habitat protection objectives and whatever factors that are present that would have an impact on success. Responders must take into consideration the oxygen and nutrient balance at the site. If the circumstances are such that no amount of nutrients will accelerate biodegradation, then the decision should be made on the need to accelerate oil disappearance to protect a vital living resource or simply to speed up restoration of the ecosystem. If there is no immediate need to protect a vital resource or restore the ecosystem, then natural attenuation may be the appropriate response action. These decisions are clearly influenced by the circumstances of the spill. TABLE OF CONTENTS Chapter 1 INTRODUCTION ..............................................................................................1 1.1 Occurrence of Oil Spills ..................................................................................1