Exxon Valdez: Studying Why, Contrary to Predictions, Oil Still Remains

Written by on March 31, 2009 in Marine Life, Other News
Exxon Valdez aground Bligh Reef in the Prince William Sound  -  Source: Valdez Science

Exxon Valdez aground Bligh Reef in the Prince William Sound - Source: Valdez Science

Contrary to past predictions, oil still remains in Alaska’s beaches 20 years after the spill.   Michel Boufadel, a hydrologist, expert in oil spills and oil remediation, is looking for answers to why the environment is still suffering the consequences of the Exxon Valdez accident.

Exxon Valdez oil spill affected area  -  Source: Exxon Valdez Oil Spill Trustee CouncilOn March 24, 1989 the tanker Exxon Valdez deviated from the shipping lane in Prince William Sound (PWS), Alaska to avoid icebergs and grounded on Bligh Reef resulting in the release of 37,000 tons of Alaska North Slop crude oil, making one of the largest environmental disasters in history.  Only ranking thirty-second in the amount of oil spilled in major tanker accidents worldwide, it was the largest in US waters and attracted a tremendous amount of attention for its effect on the Alaskan ecosystem impacting over 1,100 miles of non-continuous coastline.  As a result of this oil spill and others, there has been a considerable effort by government, academic and industry scientists to understand the fate and effects of petroleum in the marine environment.



Harlequin Duck: adult drake

Harlequin Duck: adult drake

The literature indicates that, while initial impacts of oil spills can be severe, there are very effective natural mechanisms that produce rapid recovery in most spills.  An important observation that resulted from this oil spill was that natural cleaning processes were in many cases very effective  at degrading oil.  It took longer for some sections of shoreline to recover from some of the invasive cleaning methods (hot water flushing in particular) than from the oiling itself.  However, long-term monitoring in the oiled areas has shown that fauna, such as Cormorants and Harlequin ducks, still have not recovered.  The Exxon Valdez Oil Spill Trustee Council recognizes 30 species as injured by the spill on different levels from not recovering to recovering.  It appears the remaining oil deposits may have become a chronic source of low-level oil pollution within the affected area.


Boufadel has explained that in 1994, there was a decision made to stop all remediation efforts on the beaches of Prince William Sound.  That decision was based on the rate of oil disappearance during the first four years after the spill, a rate of 70 percent, and calculations showed that the oil would be gone within the next few years.


After it became clear that the disappearance rate had slipped to a rate of only 4 percent a year, Temple University Civil and Environmental Engineering Chair Michel Boufadel spent the past two years researching why oil from the Exxon Valdez can still be found along many of the beaches in Alaska’s Prince William Sound.  They are funded by a $1.2 million grant received in 2007 from the Exxon Valdez Oil Spill Trustee Council.  It is the first such study to examine the spill’s impact on the beaches and why oil still lingers.


Exxon Valdez oil residue  -  Source: NOAA Fisheries

Exxon Valdez oil residue - Source: NOAA Fisheries

Boufadel is now trying to understand what factors are causing the oil to persist in certain sediments along the beaches.  He has been, along with several Temple environmental engineering students, collecting 50 pounds of oil and sediment samples that contain toxic material from the Exxon Valdez spill from six different beaches, as well as placing sensors to take year-round water temperature, water salinity and water pressure readings, which he is currently analyzing at his Temple University lab.


He has focused his study mainly on the geology and hydrology of the impacted areas as potential reasons for the lingering of the oil in the Sound.    Boufadel thinks to have found the reason: “We discovered on one beach that whenever you have fresh water flowing seaward from the area behind the beach you don’t find much oil,” he said.  He hopes to publish more definitive conclusions later this summer, as well as providing guidelines for locating the oil within the beaches and how to clean it up.  He will be leading another field research visit in summer in which he will explore  remediation on two of the six affected beaches.


Recovery is a very difficult term to define.  If you ask a fisherman from Kodiak Island, a villager from the town of Valdez, an Exxon engineer, or a NOAA biologist, you are likely to receive extremely different answers on the state of recovery of the affected ecosystem. Disagreements exist between Exxon and government-funded scientists, but most studies agree that the oil persisted for a decade in surprising amounts and in toxic forms and was sufficiently bioavailable to induce chronic biological exposures, and had long-term impacts at the population level.


As an environmental engineer Michel Boufadel is seeking to not only understand the factors that cause the problem, but also provide a solution to them. 



Copyright ©  2009 by Marine Science Today, a publication of OceanLines LLC

About the Author

About the Author: Celia is Director of Business Operations for OceanLines LLC and is a frequent contributor to both OceanLines and Marine Science Today. She is a certified diver and her favorite topic is marine biology, especially stories about whales. .


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