In a recent discussion on this blog, an interesting thread appeared: the idea that BP's heavy use of chemical dispersants to break up the Gulf oil spill was as much damage cover up as damage control.
Here are a few examples:
My suspicion is that the main reason they used these dispersants was to hide the oil from view.... Anything that will keep the oil out of site below the surface allows them a certain measure of plausible deniability regarding their knowledge of the spills true magnitude.
I think there is a big effort on the part of BP to minimize the aesthetic and visual impact of the spill
That makes sense, especially when you consider that they're now spreading the dispersant directly into the plume underwater. That way the oil won't even reach the surface.
The readers of this blog aren't the only ones rather pointedly raising this question. Environmental groups have done the same. This comment comes from Natural Resources Defense Council staff blogger Regan Nelson: By dispersing oil into deeper waters, away from human eyes, dispersants can also have the welcome public relations effect of making the spill appear smaller.
Or consider this one from Protect the Ocean: Dispersal of the oil does not eliminate it, nor does it decrease the toxicity of the oil. It just breaks it up into small particles, where it becomes less visible. It's still there, spewing toxicity at an even greater rate (due to higher surface area.)
This week, government scientists acknowledged that BP's public estimate of a 5,000 barrel a day leak was such a massive underestimate that it might have been closer to, um, 20,000 barrels a day. That rather than 11 million gallons of oil so far leaked that it could be 40 million gallons. And that most of that oil appears to be - surprise - under the surface.
So is BP's heavy use of dispersants - close to a million gallons so far - protecting the environment or protecting an oil company's image - and limiting potential liability?
One of the other discussants earlier this week, made the point that chemical dispersants offer a biological trade off, killing more species out in deep waters versus allowing more oil to wreck the delicate coastal breeding grounds and wildlife habitats as oil oozes ashore in a smothering blanket.
If the oil is dispersed, less will get to the fish and shrimp, more to the smaller critters further down the food chain which live in the deeper water. It's an ugly bargain, but I'm not quite as cynical as some of the other commenters who attribute it all to aesthetics for the sake of PR.
And he's right about that balancing act. There are a host of good reasons to try to limit the amount of oil reaching the coastline. The EPA has a list of some dozen approved dispersants because these have been used before, by companies other than BP, to reduce the amount of crude oil coming ashore. Certainly environmental regulators haven't argued against its use in this case.
But it's not entirely cynical to believe that BP has a mixture of motives playing out here. We could add in this one as well: the fact that U.S. regulations allow the federal government to fine $1,000 to $4,300 per gallon spilled into our waters.
So me? My cynicism levels have been increasing daily. By the barrel, in fact.
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I certainly don't trust BP's motives, but there can be ecological arguments for dispersal.
The volume occupied by the open ocean is enormously larger than the volume occupied by the shoreline. So, to the extent that damage is proportional to oil concentration, and that the shoreline is a sink for surface oil (once the oil hits the shore it doesn't wash back out to sea), then protecting the shoreline by dispersing the oil at sea may minimize the damage. Large organisms in the open ocean are mobile and may be able to sense the oil and swim away from it, but most shoreline organisms are sessile and won't be able to do that.
If the oil doesn't surface, won't the BTEX (a term I learned from this blog) volatiles fail to evaporate? And then stay underwater to be a long-term part of the food chain? Or am I missing something?
You're absolutely right, especially when one considers the fate of plants or nests of eggs. I tweaked the post a little to give that aspect a little more weight. Thanks for writing!
There are bacteria that can degrade all the constituents of crude oil. BTEX is light enough that it can evaporate and be destroyed in the atmosphere, but there are bacteria that can degrade it too.
However, it takes oxidizing equivalents to degrade oil. Either those come from O2, or (worse) from sulfate. The ocean has a lot of sulfate. When bacteria use sulfate, they reduce it to hydrogen sulfide, something that is quite toxic (slightly more toxic than cyanide). Essentially no multi-cellular organism can live in a high H2S environment (except for a few clams). If that happens there will be a gigantic dead zone, a zone where nothing can pass through it and survive.
I've been wondering about dead zones too. Hadn't considered the hydrogen sulfide effect. But we do know that as bacteria digest/breakdown oil under water, they use a lot of oxygen in the metabolic process. Some of the scientist monitoring the under water oil plumes are reporting 30 percent oxygen depletion in areas of those plumes already. Not a direction that we really hope to be going.
In addition to protecting appearances it essentially eliminates any ability/need/requirement to clean up the oil sprayed with dispersant. Every gallon of crude treated with a dispersant is one that BP doesn't have to pay to have physically removed.
There were some reports that there was vast quantities of methane mixed with this oil, that there was more methane than oil in what was coming out. Methane is easily degraded by bacteria and makes hydrogen sulfide too. That is one of the real concerns of global warming causing the methane hydrate deposits to destabilize. There is many times more carbon present as methane hydrate than there is present as oil, or even coal.
As daedalus2u points out, facilitating bio-degradation is an important reason for dispersant use.
Essentially, the dispersants serve to make the oil more biologically available. This also goes a very long way to explaining the toxic synergy where oil + dispersant is significantly more toxic than oil or dispersant individually.
You may think "more toxic = bad", but in this case, more toxic also means less time required to break it down. A tradeoff between relatively a bigger short term effect and a lesser long term effect... an acute vs chronic sort of thing.
We deal with this sort of tradeoff all the time, so no one should have a hard time understanding it. I have yet to hear anyone in the media even try to explain it though.
It is also very true that there are all sorts of other motivations, including PR and minimizing the apparent (but not actual) severity of the spill.
Also true that oil on the coast vs open water tends to be much worse. In open water the oil is spread out in 2D (or 3D with dispersant), but on the shore it is concentrated along a pretty much a 1D line.
Some of the scientists monitoring the under water oil plumes are reporting 30 percent oxygen depletion in areas of those plumes already. Not a direction that we really hope to be going.
Tony Hayward of BP has disputed the existence of oil plumes citing the specific gravity of oil vs water. We know the dispersants cause the oil to sink! He must think we are all brain dead. BP's motives seem pretty clear to me, cynicism aside.