Only a quick, back of a napkin, calculation here on the amount of gallons of oil contained within an undersea oil plume the size and density that Dr. Joye spoke about in her press release today.
Despite BP's claims, the evidence of submarine pollution is now overwhelming. Scientists at the University of South Florida also recently discovered an enormous amount of oil at about 1,000 meters (3,280 feet) beneath the surface. The cloud of finely dispersed oil particles extends for 35 kilometers, billowing to the northeast of the Deepwater Horizon accident site. It's one of the most species-rich regions of the Gulf of Mexico.
There are (about) 16.6 million gallons of crude oil in this single undersea plume
this is equivalent to 395,200 barrels of oil.
note: this amount of oil, corrected for consumption by microbes over the last 45 days, is greater than the amount of oil being currently collected by bp IF BP WAS COLLECTING THIS SAME AMOUNT OF OIL SINCE THE BEGINNING OF THE SPILL.
'Out of Sight, Out of Mind'
What can be done about the oil clouds beneath the ocean surface? The scientists don't have any answers. And the ghostly oil shroud is growing larger and larger. Samantha Joye and her team have located a cloud near the damaged wellhead that is about 15 kilometers long, 5 kilometers wide and 100 meters thick. Besides, the oil farther to the south appears to have reached the Loop Current, an ocean current that could carry the oil to Florida. Other currents could even carry it up the US East Coast and into the Gulf Stream.
The scientists' greatest concern is this year's hurricane season. "A powerful storm would be enough to distribute the oil throughout the entire water column," warns James Cowan, an oceanographer at Louisiana State University.
A technology to remove the pollution doesn't exist. Besides, BP is hardly likely to clean up the water voluntarily. In fact, it might suit the company all too well if the disaster remained hidden beneath the waves, says Cowan. "Out of sight, out of mind."
According to this interview with the NOAA researcher Samantha Joye an undersea plume can be characterized as an undersea cone. (see time 1:39)
(note: Dr. Joye is more concerned about the methane which has now depleted the oxygen in the plume to a point where it is starting to "stress" underwater organisms. methane concentrations are hundreds of times greater than normal in these areas. This means, without a doubt, this undersea plume will become an oxygen depleted dead zone and will stretch for hundreds of miles as it enters the loop current.)
This undersea cone is estimated as having a radius of 6.5 miles and a height of 3,300 feet.
the volume of such a cone of water is equivalent to 26.5 cubic miles of water.
to check the calculation:
the volume of a cone is = 1/3 * (pi) * radius^2 * height
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now, to find out how much oil is in this plume, one must first determine what the concentration of oil is. thankfully, the NOAA provided this information.
NOAA: Under Water Oil Plumes Confirmed
NOAA Says Water Tests Confirm Underwater Oil Plumes At 'very Low' Concentrations.
Lubchenko said the analysis "indicate there is definitely oil sub surface. It's in very low concentrations" of 0.5 parts per million.
warning: Math Below
ok sooooo if the, "very low concentration" is only .5 parts per million that means that for every 2 million grams of water there is a single gram of oil.
but how can we find out how much oil there is if it is reported to us in grams????
don't worry! it is easy.
first off, we assume that the oil is exactly the same as water by using a new unit called "weight-gallons of water" (don't worry, we will fix this later)
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volume ratio of oil in the plume
ok, in every cubic mile of water there are 1,101,117,140,000 gallons
so for 26.5 cubic miles of water there is (26.5 * 1,101,117,140,000) gallons (thats a lot!)
then, because the concentration is .5 parts mer million you divide the number of gallons by 1 million and then multiply by .5 to find out how much the oil would weigh in the water (if the oil was exactly like water)
This plume at .5 parts per million, would hold 14,589,801 gallons of oil.
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weight-volume ration of oil
but remember, oil is different from water, that is why it floats! so what we really have is 14,589,801 "weight-gallons of oil" (we are still pretending oil and water weigh the same)
we will now convert the oil "weight-gallons" into real gallons to find out how many gallons of oil are in the plume.
to convert to actual volumes we use the specific gravity which is the ratio of weights and volumes of the oil compared to water.
The specific gravity of crude oil is: .900
The specific gravity of sea water is: 1.025 (remember it is easier to float in salt water!)
so the conversion factor of weight to volume for this material when measured as parts per million (weight) is
conversion factor = .9/1.025 = .878
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hey oil floats!!!
That means that the weight to volume ratio of the crude oil to sea water is .878. or, for a given volume of oil, it will weigh .878 as much as the same volume of sea water. (hey! that is why oil floats!!! -- exactly!)
so we can now convert the "gallons of oil" into real gallons.
14,589,801 "weight-gallons of oil" / .878 = 16.6 million gallons of crude oil.
This means that in a cone-shaped plume of sea water with a radius of 6.5 miles and a depth of 3,300 feet and a concentration of .5 parts per million:
there is (about) 16.6 million gallons of crude oil in this plume.
--innereye
These are not the only plumes in the gulf.
calculation cheat sheet:
liquid volume of plume = 26.5 cubic miles
there are 1,101,117,140,000 U.S. liquid gallons per cubic mile
average concentration of oil in the plume = .5 ppm
ratio of specific gravity of gulf crude to salt water = .9 / 1.025 = .878
gallons of oil in the plume = 26.5 cubic miles * .5 kg / 1 X 10^6 kg * 1,101.1 X 10^6 gallons per cubic mile / .878 (conversion factor weight to volume)
= 16.6 X 10^6 gallons of crude in the 26.5 cubic mile undersea plume
this is equivalent to 395,200 barrels of oil
update:
for more information on the methane and oxygen depletion, see the Dr. Samantha Joye blog
update II:
to see more that I have written regarding the methane in the water column and long-term oxygen depletion (leading to hydrogen sulfide release in the anaerobic consumption process) see this diary