Oil on the bottom of the Gulf

by Kert Davies

September 27, 2010

Now that was a totally new experience! Last night I got to touch clay and mud fresh from the bottom of the sea, 1,300 meters (4,000 feet) deep in the Gulf of Mexico. That was fun. Today we pulled up a sample and opened the lid to see little patches of oil sheen bubbling up. That was sad.

Here aboard the Greenpeace ship Arctic Sunrise, we are continuing our three-month science mission in the Gulf of Mexico. We are floating about five miles north of the Deepwater Horizon well site, in water that would have been covered with oil a few months ago, where thousands of gallons of oil were skimmed and burned on the surface while  an armada of boats and planes delivered daily bombardment with chemical dispersants that sunk the oil back underwater into the path of any unlucky sea creatures nearby.

Aa I soaked in the surreal scene in the middle of the night, and how privileged I am to be out here doing this work, I thought of the eleven men who lost their lives here just a short time ago. Missing my kids after weeks away from home, I thought of those men and their mothers and fathers, wives and children.  That was sad.

This place is truly an historic environmental war zone and it’s quite sobering to be here. 

Now things look quite different;  to the naked eye, the sea here looks like it would have before the series of events that began on April 20th.  At the Deepwater Horizon site we can see about six ships and two towering Transocean drill rigs, all part of the disaster response that ran all summer long, drilling and trapping oil from the blowout.  As one scans the horizon 360 degrees around, there are large oilrigs are visible in every direction at various distances.  

We are at the frontier in a very industrialized body of water.  There are not many rigs farther south of here, yet, but  many deepwater projects are planned for the Gulf of Mexico, by Shell, BP, Chevron, Exxon and others. To the north in shallower water, the Gulf is quite crowded, with some 3,500 active drilling rigs, 27,000 abandoned wells and hundreds of miles of pipeline lacing the bottom along the continental shelf from Texas to Alabama. I have been told that this is   the most industrialized portion of the ocean in the world.  A sacrifice zone.

To the bottom of the sea.

Last evening we started an exciting chapter of the science mission, launching the first in a series of bottom samples using a contraption called a ‘box core.’  The thing looks like a huge guillotine over a large metal box with trap doors on the top and bottom.  The box core is lowered to the sea floor on a very long cable where it slams deep into the mud and snaps shut.  In this case it went down 1,300 meters. When it hits we reel back to the surface and manhandle it onboard.  Immediately the scientists take samples of the water that is also trapped by the box, that which used to be just above the bottom of the Gulf They take portions of the sediment away for various analysis.  They will check for hydrocarbons, macro and microscopic life and share samples with geologists, biologists and other scientists around the country.

Box Core launch

They skim off the top 15 cm(7 inches) of mud into buckets, then gently rinse this through fine mesh sieves to see what creatures are to be found.  Some samples are immediately frozen.  Smaller core samples are taken using plastic tubes and these are also preserved for future analysis.  This team and scientists all over will be analyzing these samples for months, and maybe years to come.

When I looked into the box core, I was effectively looking at the bottom of the Gulf of Mexico. I could see brownish gray mud, with small worm tubes sticking out occasionally. Below that is fine smooth gray clay, like you would make pots out of.  Over geologic time, this might turn into shale and slate.  We will conduct as many of these box core samples as we can at several locations around the Deepwater Horizon site over the next few days.  Teams of independent scientists have recently pulled up bottom samples near our location with oily residue on top using  similar devices.  And luckily, there is baseline data going back ten years for this area, before oil drilling was permitted this deep. After analysis onboard and back at the lab, the scientists will have a better understanding of the state of the ecosystem at the bottom, how it reacted to the oil spill.  This lab work will take some time.  As soon as possible we shall see and report what the scientists find.

Deep questions

The first BIG question that came to my mind was – why is there oil on the bottom of the Gulf? Doesn’t oil float? 

The second question was why is the oil so fresh and smelly and liquid? Aren’t those oil loving bacteria supposed to be breaking it down?  Or is it more like what other scientists have said, that the bacteria are unlikely to be as active at such extreme pressure, low temperature.

And the third question is the “oil budget calculator” that NOAA put out.  I may be mistaken, but I don’t remember a slice of the pie chart for “OIL ON THE BOTTOM“.  How much is down here? did it come straight from the busted well? was it hit with dispersant that made it sink?  or did it rain down from the surface after being hit with dispersant?  All open questions

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