Our weather started out pretty rough but improved steadily over the course of the day and is now quite tolerable. We continued our efforts to map the apparent deep flow of oil by extending out transect and sampling on either side of it. These data continue to support our hypothesis that the currents at depth are consistently transporting the oil to the southwest. We learned today that AXBTs (or similar disposables) dropped by a NOAA P-3 also show this flow so our confidence in this interpretation is increased.
Part of the sampling today included more samples for chemical analyses of PAH (polycyclic aromatic hydrocarbons) and total CDOM. These samples have focused on the layers with the most CDOM fluorescence but
several “control” samples have also been obtained in low fluorescence layers.
Our final activity of the evening was to re-occupy several of the sites where we first observed the high fluorescence values at depth. These are all very close to the accident site and all continue to show strong signals in fluorescence, beam attenuation, and oxygen. However, we noted that some of these layers have been displaced vertically so we are anxious to return to the lab where an analysis of their positions relative to sigma theta levels can be conducted.
Our plans for the final day of the cruise will take us to the end of this transect, a point 20 miles southwest of the leak site, where we will deploy the Acrobat package for a transit back in the direction of the accident site. This should last until 21:00 when we will need to start our transit back to Cocodrie, but any remaining time will be used for additional Acrobat transects across the axis of the long, southwest radial. The pCO2 sensor uses a novel floating platform to keep its intake in position just under the sea
surface. These data will be interpreted by Sylvia Musielewicz at NOAA’s PMEL laboratory and will be integrated into the entire cruise data set.