[Coral-List] EcoRigs Report on Subsurface Oil and Disperant Plume at MP 311
stevekolian at hotmail.com
Thu Aug 12 09:20:26 EDT 2010
This report includes observations from an EcoRigs scuba sampling trip on the east side of the Mississippi to Main Pass (MP) 311 on August 8th 2010. We were surprised by what we found. The subsurface oil and dispersant plume layer was larger, the water more turbid and currents were swifter than we normally encounter. We periodically saw scummy foam and oil sheen on the surface and oil on the pilings and a heavy murky plume in the upper 40 to 45 feet. The water cleared up at about 45 feet and we saw white noodles at 45 to 60 feet. Noodles are stringy white material that appears to fall out of subsurface plumes that are located in the water column above. We recorded a few on videotape, but we missed catching a flurry of them on videotape when the noodles were coming down like snow.
The currents were extraordinarily swift, 5 mph down to 60 feet (the extent of our dive). I was holding on to a pipe and the current forced me horizontal, like a flag in a strong wind. The plume was much more turbid than any other time in the past, with the exception of a dive on Mississippi Canyon (MC) 194 on June 24.
On a previous visit to MP 311 on June 6th, we observed a similar noodle phenomenon which was described, on the scene, as big balls of brown “snot”.
We also have a video of MP 311 on May 19th and you can see materials from globules, flakes and small particles fine materials and dissolved oil and dispersant.
The May 19th video at MP 311 shows particulate oil and dispersant moving down the water column. The oil has not yet broken down to fine materials, as seen in the June 6th and August 8th video. The oil appears to be in transition to finer material, which may be caused by agitation from the wave action and currents. The water is relatively clear and fish do not appear to avoid the areas occupied by the oil and dispersant debris layer.
Finally, a video from October 2008 is presented for reference to view water conditions before the Deepwater Horizon spill.
I should note that MP 311 is on the east side of the Mississippi River (14 miles) in 250 ft of water and in a marine transition area, where the water is sometimes green due to freshwater flows, from the Mississippi, on the ocean surface. When wind and currents blow from a southerly direction, as it often does during the summer, blue ocean currents prevail and the water conditions around MP 311 are blue and clear. When fresh water prevails, there is a greenish layer in the upper 10 -20 feet called murk. The fresh water gets pushed east or west of the Mississippi depending on prevailing wind and currents. When the winds are from the easterly direction, the surface water is blue at MP 311 and the murk is west of the Mississippi.
We are very cognizant of the fact that we may be mistaking the oil and dispersant plume for a freshwater plume. There are characteristics that distinguish the two, first, the presence of the noodles or snot falling down the water column indicates that the plume is not just fresh water. Secondly, plume has a different mixing pattern than a freshwater layer. Looking at the oil and dispersant plume from below, the underside of the plume billows and is not an even layer like fresh water. The fresh water and the oil plume can both be present; however, the combination is much darker than freshwater alone. A freshwater layer was present on August 8th and May 19th but not so prevalent as in October 2008.
We are presently collecting water samples and testing for Total Petroleum Hydrocarbons (TPH) and Trace Metals to verify our observations.
Best Regards, Steve Kolian 225-910-0304 cell
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