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Spilled oil is spreading in hidden plume

Fig 45 copy 400.jpgThe US government has acknowledged what scientists first reported nearly 2 months ago—that a deep plume of diffuse oil was spreading away from the leaking Deepwater Horizon/BP well and that oxygen concentrations in the vicinity were below what is expected in that region. The Joint Analysis Group, or JAG, today announced that elevated oil concentrations could be found up to 25 kilometres from the wellhead at depths between 1,000 metres and 1,300 metres. The report notes that some natural oil seeps are in the vicinity of the wellhead but that the “subsurface oil concentrations are highest near the wellhead and become more diffuse farther away from the source,” according to a NOAA release. (In the accompanying image, which is figure 45 in the report, reddish hues represent the highest readings associated with oil, while blue depict the lowest readings. The white dot is the well location). The JAG did not say anything about the environmental consequences of the spreading oil.

The report also documented a depression in dissolved oxygen below 1,000 metres, which could be caused by microbial consumption of the oil and methane spreading away from the wellhead. But the JAG said that the oxygen levels are not low enough to be of concern.

Scientists on board the R/V Pelican first reported finding a deep plume of spreading oil, as well as depressed oxygen concentrations, during a cruise in May.

Image: Joint Analysis Group


  1. Report this comment

    Brian J. Donovan said:

    BP’s Strategy to Limit Liability in Regard to Its Gulf Oil Gusher

    Underwater plumes are the result of the excessive and unprecedented use of dispersants, merely one tactic in BP’s strategy to limit its liability.

    This article briefly discusses BP’s strategy to limit its liability in regard to the Deepwater Horizon blowout. This strategy includes, but is not limited to, intentionally underestimating the rate of flow of oil that’s being released into the Gulf of Mexico, prohibiting independent measurement of the BP oil gusher by unbiased third party scientists and engineers, the excessive and unprecedented use of dispersants (both on the surface and underwater), systematically and intentionally collecting as small an amount of oil as possible from the waters of the Gulf of Mexico, and controlling and restricting media access to the areas affected by the Deepwater Horizon oil gusher.

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    Lang said:

    In reviewing the NOAA summary the authors fail to comment on the presence of dissolved methane and make only fleeting reference to the gas component of the flow. In addition they appear to downplay the impact of dispersants quantifying their usage for the 30 day period of the field research rather than total from first use. It should be noted that the authorship is primarily restricted to members of federal agencies and the White House and excludes scientists who led some of the research cruises. The conclusions appear contradictory as they call into question the data on DO2 while suggesting the levels are not at hypoxic levels. Moreover they appear to have selected an hypoxic threshold below the widely accepted 2mL/L. It was disappointing that there was no discussion of the inverse relationship between microbial activity and CDOM fluorescence values. The NOAA press release associated with the summary implies that there has been three months of continued field investigations, which is misleading.

    The scientific community has been been requesting that NOAA provide open access to the data that has been gathered. To date those requests have been only minimally granted. Of concern is the unofficial moratorium on research cruises initiated by NOAA’s director in early June and the lack of urgency in establishing research criteria.

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