Sinking or Floating BP Oil – Which is Better?

With the Deep Water Horizon oil leak at least temporarily capped, discussions are rampant about the oil that was released into the ocean.

What is the possible damage that will occur? Does it cause more harm for the oil to be on the surface or if the oil sinks below. What is required for completing the cleanup? Is it even possible to complete the cleanup?

Is there some previous data from oil spills of similar circumstances that have already occurred that can be used to get some answers?

For the shoreline oil spill example, let’s look at the Exxon Valdez spill. What are the long term results?.

This is from a recently broadcast CBS report on the Exxon Valdez oil spill, 21 year later.

Over the course of 56 days, the black cloud spread damaging 1,300 miles of shoreline. Ten thousand people helped clean it up. It took more than four summers and cost Exxon $2.1 billion.

Faulkner lives in Cordova, the largest fishing town on the sound. Twenty-one years later, things look pretty normal.

“Well it does look nice and normal but we don’t have any herring,” Faulkner said.

That’s why Mark King’s boat is parked in a warehouse. The former herring fisherman used to pull in up to $150,000 per year. Now he makes about $50,000 fishing salmon. Herring basically disappeared within three years of the spill.

King’s hope was to pass on his business to his kids.

“They’re gone,” King said. “They aren’t involved in fishing. They didn’t have the opportunities I had growing up here.”

While herring populations are still devastated, other species such as salmon and bald eagles have recovered. But perhaps the most remarkable is what never went away – and you can find it just a short plane ride from Cordova. On the shoreline, all you have to do is move a couple of rocks and you strike oil – Exxon Valdez oil – 21 years later.

In fact, over 21,000 gallons of oil are left from the spill. It is naturally decreasing at a rate of 0 to 4 percent per year. So it could take decades – or even centuries – before it’s all gone.

Researcher David Janka said that two decades later, the oil is still a threat.

One example of oil that sank into the seafloor, but at a much lower depth, occurred during the first Gulf War.

When oil was floating on the surface of the Persian Gulf, several sandstorms occurred that caused the oil on the surface to bind with the sand and sink to the sea bed.

The picture below shows some mussels taken off the tidal flats in the Persian Gulf, 2 years after the spill. Note the oil that was released when the mussel was removed.

But the BP oil spill in the Gulf of Mexico falls into a distinct category from any other oil catastrophe; it’s the first blowout in history to release oil in such deep waters, nearly a mile below the surface.

Perhaps the closest thing that could be compared to the BP leak is the Ixtoc blowout of 1979-80, even though it happened in much shallower water.

Ixtoc soiled hundreds of miles of beaches, all the way to Texas. The immediate damage was the oil killed 50 percent to 80 percent of the bottom-dwelling creatures in some areas near the Texas shore. But then something unexpected happened. Because oil constantly seeps into the gulf from natural fissures, the water is teeming with microbes adapted to break oil down and use it as food.

The breakdown happens faster there than in colder bodies of water, and the warm water helps some species recover faster, too. Along the Texas coast, within a few years after the Ixtoc spill ended in 1980, it was hard to tell that anything had gone wrong. Creatures repopulated the areas that had been wiped out.

So to answer the question, is it better for the oil to sink or to float? There are so many unknowns that the question cannot be answered. If all of the oil stayed on the surface, it would have created much larger visible damage to shorelines, birds, turtles, etc. But the damages that may be caused by the dispersants would have been avoided.

With the use of dispersants injected at the leak point to try to reduce the amount of oil coming to the surface, large amounts of oil are below surface in plumes.

Will this cause oxygen depletion on the sea floor? Will it cause major disruptions in the food chain? What will be the effects on marine biology when the toxins of the oil dissipate and spread throughout the water?

This BP leak is an entirely new event, creating many variables not dealt with before. Scientists do not know the answers to the above questions and may not until many decades of time.

But all agree that the environmental stakes are high.

Comparisons of some previous oil spills in magnitude.

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