Just after midnight on this day in 1989, the oil tanker Exxon Valdez crashed against a reef off the coast of Alaska. Within six or so hours of the incident, nearly 10.8 million gallons of crude oil had spilled into the surrounding waters of the Prince Island Sound. Within a few days, that oil had spread 90 miles from the accident site. And now, two decades later, the after effects of the Valdez spill linger.
Oil and Water
In 1989, America consumed over 252 billion gallons of oil. Compared to that number, the 10.8 million gallons that was dumped from the Valdez and into Prince Island Sound seems insignificant. In fact, the Exxon Valdez spill was by no means the largest spill in history. It wasn’t even the tenth largest.
But it wasn’t the size of the spill that was the issue; it was where the spill occurred. Prince Island Sound is in a remote area of Alaska, accessible only by plane or ship. It took hours for clean-up crews to get there, time that proved very costly in terms of ecological damage. That 10.8 million gallons was enough to poison thousands of fish, sea birds, and marine mammals throughout the region over the following months. That devastating impact on the ecology of Prince Island Sound is why the Exxon Valdez oil spill is widely considered the greatest environmental disaster in U.S. history.
And 20 years later, there is still oil in the water.
Exxon Valdez Legacy
Why is oil still polluting the beaches of Prince Island Sound? In 1994, it was determined that further remediation, or clean up of the area, would yield no environmental benefits. This decision was based on the rate of oil disappearance (the rate at which it would remediate naturally) at the time, calculated at around 70 percent. Yet seven years later, in a study conducted by NOAA, it was determined that oil was in fact degrading at a rate of only four percent, and at some locations it didn’t seem to be going anywhere at all. Today, you can dig a shallow hole in the sand of any number of beaches in the area, and find oil. This disturbing revelation led the Exxon Valdez Oil Spill Trustee Council to ask for a whole new study on why oil is lingering in the area.
Enter Michel Boufadel, hydrologist and professor of environmental engineering at Temple University. He and his team received a $1.2 million grant from the Council to study the problem. They’ve spent the last two years taking measurements and analyzing their data.
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It hasn’t been easy, due mainly to the difficulty in determining where to search for the remaining oil. There are countless beaches on the shores of Prince William Sound, and countless places on each beach where oil might or might not be lingering.
As Boufadel puts it, “You look at one location, you find oil. You move twenty feet to the left or to the right and you find it’s very clean.”
What makes one location more or less likely to have oil sticking around? Boufadel says a number of factors contribute, but a major one that he and his team have discovered is the presence of fresh water.
Boufadel found that in areas fed by groundwater, or fresh water from farther inland that sinks into the soil and eventually washes out to sea, the amount of oil is far lower.
“So we think there’s a relation between the amount of freshwater going to the sea, and the presence of oil,” says Boufadel.
Why should fresh water flow affect oil on the beach? Boufadel believes it may have to do with the microorganisms living there. Certain tiny organisms, living in the soil and water near the beach, are able to naturally degrade oil. If they have a steady supply of oxygen and nutrients, they can continue to take carbon out of the oil, eating away at petroleum slowly over time. But in areas of stagnation, where there is no freshwater flow to bring in fresh nutrients or oxygen, these microorganisms are unable to function properly. Without their help, the oil remains where it is.
Boufadel hopes that once he and his team have finished analyzing their data, they will be able to provide the Council with a guide to not only finding where the oil is, but also the best way to clean it up. The techniques and technologies for cleaning up spills in the open water hasn’t changed much in the past 20 years. The strategies used to clean up the Valdez spill are the same used today. But Boufadel claims that there is one area where there has been significant advancement: delivery of chemical nutrients to bacteria on the beaches.
That could be a lucky break for the microorganisms struggling on the shore of Prince Island Sound.
Previously, these chemicals could only be released over a short period of time, like six hours. Now, the bacteria can be fed by a sustained release over 60 hours, giving them more time to absorb the nutrients and steadily eat away at the lingering oil.
What will be the fate of the Prince Island Sound beaches, and the organisms, big and small, that make their home there? We still don’t know. There are a number of species that have yet to fully recover from the devastating effects of the Valdez spill.
We can only hope that the next 20 years will see the last of those effects washed away.
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