The 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