14 DAY TRIAL // On July 23, US authorities released their second report on the situation of the waters surrounding the site of the former Deepwater Horizon drilling rig. The document found that the levels of oxygen depletion in the area were not very significant, and that there was no real danger of the situation getting worse. But information collected from the same area by independent research groups paint a different picture. These scientists say that they've identified a strong decline in oxygen levels, a phenomenon that may have significant repercussions on the area, Nature News reports.
The government responded to these critics by saying that the subsurface oil around the accident site is currently moving and breaking down. Experts from various federal agencies believe that the independent research groups may have collected irrelevant or bad data, which may have prompted them to reach different conclusions. The official version of what's currently going on in the Gulf was elaborated by the Joint Analysis Group (JAG).
This organization includes experts from the US National Oceanic and Atmospheric Administration (NOAA) and the White House Office of Science and Technology Policy (OSTP), who collaborated closely with colleagues from a number of other agencies. The samples on which the conclusions were based come from about 227 sampling sites spread around the area of the spill. These stations can be found between 1 and 52 kilometers away from where the semi-submersible drilling rig sunk. The new document confirmed the conclusions of the first report, which showed that contaminant concentrations were decreasing as distances increased from the accident site. The spread of subsurface oil is also consistent with existing marine currents, JAG experts write in the document.
“The Joint Analysis Group is working to ensure the vast amounts of data being collected in the Gulf are compiled, synthesized and analyzed in a comprehensive manner. This is the best way to ensure the Unified Command is benefiting from a full understanding of the available information, and that relevant findings and lessons are being shared with the responders as well as the broader research community,” explains the head of JAG, NOAA Chief Scientist for Fisheries Steve Murawski.
“There's some indication that perhaps we're getting false positives for oxygen decline because the membrane is being fouled,” he adds. The expert explains that the “official” research crews used a variety of analysis methods for measuring the amount of oxygen that still exists in the water. Their conclusions were not alarming. “I don't think we'll have a situation of complete anoxia [absence of oxygen] in the deep water. The deep sea is quite well aerated, with a lot of oxygen-rich water around,” explains University of North Carolina in Chapel Hill microbiologist Andreas Teske.
But critics to the JAG document say that samples collected at the accident site are not relevant, because oxygen-consuming microorganisms have not yet had a chance to grow there. “What I'm most concerned about is the community effect – what happens when you create this giant bloom of certain kinds of bacteria that are favoured by the availability of methane and other gases. These are ecological effects that we've never observed naturally,” says Florida State University oceanographer Ian MacDonald.