important means of improving the efficiency of washing the beaches without the need for high water temperature. However, government authorities never approved widespread use of COREXIT 9580 in Prince William Sound.
Application to Today: For inaccessible rocky environments, cleaning techniques developed for the Alaska cleanup are a means of efficiently removing bulk oil and thereby protecting species from further contamination.
Use of bioremediation on the VALDEZ spill provided impetus for international interest in this technique for spill cleanup. A large number of follow-on studies in Canada, Norway, France. U.K. and the U.S. have been carried out since, generally confirming the findings in Prince William Sound. It continues to be an attractive option for accelerating oil removal from shoreline environments. However, bioremediation is primarily effective for removing whatever oil remains after removal of the bulk oil, including sub-surface oil. Therefore, its main advantage is rapid improvement of the visual appearance of the beaches.
Secondly, the presence of high concentrations of fine sediment may signal rapid recovery in terms of oil removal. Definition of the size and characteristics of naturally occurring fine sediment in areas of spilled oil may provide a better understanding of how long it will take for beaches to recover. Tests are underway to determine if addition of fine sediment can effectively accelerate natural cleaning. Exxon scientists were recently granted a U.S. patent for this technique.
Chemical beach cleaners can facilitate cleanups of oiled shorelines by improving the efficiency of washing with water. In subsequent spills after the VALDEZ, COREXIT 9580 has more than lived up to the early expectations. It was tested by NOAA on beaches in Puerto Rico and has been used to clean shorelines in Texas and in Canada. The Canadian government's own labs in Ontario have confirmed not only that it is the most effective cleaning agent available, but that it is also the least toxic to rainbow trout - the Canadian toxicity test species (2). This product, developed during but not used in the Alaska cleanup is now the only beach cleaner which is allowed to be used in Canada. COREXIT 9580 has also been shown to be non-toxic to vegetation. Tests by professors at the University of Miami and at Louisiana State University have shown that it is one of few options for cleaning oiled mangroves and marsh grass (13) (11). It is particularly helpful in spills of heavy oil which are very difficult to clean using water alone.
Summary
The EXXON VALDEZ spill was an unfortunate accident which happened to an oil company with one of the best marine safety records in the oil industry. It demonstrated that oil spills can happen to anyone, at any time unless constant vigilance is sustained and emphasized. It was a milestone event, not just for Exxon, but for the entire U.S. oil industry. Prevention is clearly the first priority and Exxon has taken a number of specific steps to reduce the risk of oil spills and to strengthen response capabilities. New Exxon systems have since been implemented which have reduced the rate of spillage from an already impressive record. In the U.S., the total number of Exxon oil spills reaching water has dropped 60% since 1990. Between 1990 and 1995, only 250 gallons of oil have been spilled from Exxon vessels, representing less than 0.01 % of the total oil spilled from all U.S. vessels.
The VALDEZ experience also yielded important lessons about management of a crisis as well as several new technical options for dealing with spills. Important summary messages are:
・ Timely, effective action - the kind needed in an emergency - cannot be taken by committees. Someone who can weigh the issues, cut through the disagreements and force timely action with overall net environmental benefit in mind must clearly be in charge.
・ Response technology must be approved in advance and no option should be ruled out. In many cases, dispersants are an important tool for responding to a large spill, but their use must be cleared in advance so that they can be rapidly applied while their use is most effective.
・ Learnings from Exxon's application of techniques for accelerating natural recovery of shorelines have been extensively documented and shared with others. Each of these has been the subject of numerous follow-up studies internationally. Many are still ongoing and Exxon's R&D funding continues to support a number of them.
・ Bioremediation and the Chemical cleaner COREXIT 9580 were demonstrated to be safe and effective techniques for certain cleanup objectives.
