THERE have been some notorious oil spills in the last 50 years. The name Torrey Canyon I remember from my schooldays, a huge oil tanker that ran aground off the coast of Cornwall spilling its cargo of some 120,000 tons of crude oil into the surrounding seas. This was the world’s first major oil spill and was an abject lesson of how not to deal with this type of incident.
The response to this case was to spray thousands of tons of toxic dispersants into the sea in an attempt to disperse the oil slick, and to order the Royal Air Force to drop 42 bombs on the ship followed by cans of aviation fuel to try to burn the oil. When the blaze was extinguished by high tides, napalm was used to get the fire going again.
The result was that some 50 miles of the French coast were heavily contaminated along with over a hundred miles of Cornish coastline. Many species of marine life were snuffed out over a wide area. Since the Torrey Canyon there have been many more dramatic pollution incidents, including the Braer off Shetland in 1993; the Amoco Cadiz off Brittany in 1978; and perhaps the most famous of all, the Exxon Valdez in Prince William Sound, Alaska, in 1989.
And whilst this last-mentioned oil spill was comparatively small when compared to any of the first three mentioned, its impact on the pristine coastline of Alaska was considered to be one of the most serious man-made environmental disasters ever to occur.
We have learnt a lot about cleaning up oil spills since these events plus a lot about the long-term impact of this sort of disaster. For instance, in sheltered areas such as Prince William Sound where there is a soft sandy sediment on the sea bottom, spilt oil can be quickly buried in the sand only to turn up years later with adverse effects.
And marine life continues to be affected for many years as evidenced by work done on Fiddler crabs which has shown them to have changed feeding habits, escape responses and burrowing activity as long as 40 years after a significant oil pollution incident.
During the clean-up after the Exxon Valdez, high-pressure jets of hot water were used to scour the oil off the polluted beaches in order to make them habitable for larger life like seabirds, seals and otters. And to give the cosmetic appearance that something was being done to right the wrong that had occurred. However, there is plenty of evidence now to suggest that this had a more damaging effect on the ecosystem than the oil itself because it denuded the beach of all micro-organisms that were able to “digest” the oil. Some experts believe that sometimes it can be better to simply let nature take its course.
All what has been learnt is extremely relevant to the current crisis unfolding in the Gulf of Mexico. As some 5,000 barrels of oil a day continue to leak from a fractured pipeline into the Gulf, the resulting slick is constantly threatening the southern coastline of the USA. The states of Louisiana and Mississippi are currently bearing the greatest risk but Alabama and Florida are also in the frame. How serious is the threat to the ecosystem? Frankly speaking, pretty damn serious.
The area in question holds about 25% of all US wetland habitat and is home to a whole range of birds; aquatic mammals like manatees and dolphins; alligators; and a host of fish such as the already heavily depleted blue fin tuna which, over the next couple of months, is scheduled to use the very region covered by the slick for its annual spawning.
Fortunately so far, the amount of oil leaked is small by oil tanker disaster standards. Oil breaks down naturally in seawater and this will happen faster in the warm water of the Gulf than in the cold waters off Alaska.
So preventing the oil from reaching the shore is a priority and floating booms can and have been deployed for this purpose. In rough seas, however, the oil simply slops over them and the threat may extend over many hundreds of miles of coastline.
Fortunately too, solvents based on vegetable oil are now available and these are very effective at dispersing the oil with a minimum adverse effect on the environment. Thus, we are constantly learning about how to deal with oil spills which is probably just as well since they are likely to occur for as long as our energy policy relies heavily on the discovery and exploitation of crude oil.
The crisis in the Gulf of Mexico is therefore a timely reminder of the pressing need for us to move to a renewable and sustainable energy supply for our global economy. And one that does not pose major risks of pollution to any of the world’s fragile ecosystems.
