Oil spill science: Mapping the plume

Today the seas have picked up with swells over 2 metres, causing everyone to walk a bit troll-like for balance when the ship rolls, and limiting operations. The team can't safely lower the box corer because it weighs over 500 kilograms empty, and that's not something you want swinging your way when the ship lurches. But the sampling rosette poses no such threat, which works out well because that is the most critical tool in the continuing hunt for the bounds of the plume discovered yesterday.



Today, as far as 37 kilometres out from ground zero, the readings still show signs of the plume. There is no longer a signal for dissolved oil on the fluorometer, but according to the transmissometer there's still a layer of particles, and that could contain un-dissolved oil. Oxygen levels remain low, as they have throughout the plume, suggesting heavy microbial activity, perhaps as the little buggers consume dispersed oil and any organic material associated with it.

Because we're so far from ground zero, I was surprised to look up during a transit this evening and see a massive drilling rig filling a galley porthole (below). It was Transocean's Development Driller II. Internet reports say that, after inspection of the rig by US Coast Guard bigwigs, crews are taking it out to the accident site to begin drilling a second relief well.



Tonight and tomorrow morning we'll be heading out as far as it takes to find the end of the plume. We'll likely end up about 70 kilometres from ground zero, at a spot the team used as an initial control site at the start of their work on 4 May, when the water seemed free of oil contamination.

Once the researchers delineate that western end, they'll work around in search of the northern reaches. Yesterday the team found the southern edge, so tomorrow's work should complete a rough view of the plume's boundaries, though of course there is no guarantee it's anything approaching symmetrical. On Saturday we'll be running back to some of the previously sampled sites to see if the plume is moving up or down.

More: http://blogs.nature.com/news/thegreatbeyond/2010/05/oil_spill_science_mapping_the.html