Our cruise is winding down and we’re in the process of making copies of data, cleaning and rinsing gear, and packing our boxes. While the original goal of this cruise was to use our AUVs to map hydrates and shipwrecks, the actuality of this cruise was perhaps more productive and useful than we could have imagined.
The revised goals of the cruise, once our AUV plans were abandoned, were the acquisition of baseline samples of surface sediment at several sites near the accident site for comparison with later samples, and the determination of whether or not the oil was sinking and, if so, how long it might be before it reached the seafloor. The CDOM (Colored, Dissolved, Organic Matter) fluorometer that we bought for the latter purpose worked very well and we are confident that we detected oil not only below the surface but in deep layers that are apparently advecting towards the southwest.
Our activities today include acquiring more CTDs to complete our oil plume mapping work, and a very long (7 hours, 30+ miles) transect with the Acrobat and fluorometer. All of this went well, in spite of the rather poor weather and rough seas. Of interest in this transect was the observation several layers of water near the surface that exhibited higher salinities than the water above them and were apparently devoid of CDOM. These pockets of water were of very limited lateral extent and we look forward to making a detailed
analysis of their origin and possible impact on the degradation of the oil. From here, we will steam towards Cocodrie with an anticipated 06:00 arrival, after which we will offload the equipment, disperse the samples and return to our offices. This has been an exciting and challenging cruise and, while we are proud of the contribution we have made toward understanding the fate of the spilled oil, we hope that this first trip to the site is not our last