"June 1, 2011"--Cover. "June 11, 2010"--Pp. 1-9. Includes bibliographical references.

"This report considers data collected by the R/V Brooks McCall near the site of the Deepwater Horizon MC252 between May 8 and May 25, 2010. The Deepwater Horizon MC252 was releasing methane gas and oil in a turbulent mixture from the broken riser pipe attached to the well during this time. A plume of oil and gas rose from the release point; most of the oil reached the surface in about three hours. During the trip to the surface, some of the oil dissolved in the water column and some formed droplets. The pressure that propelled the oil out of the wellhead was strong enough to cause at least some of the oil to form water-in-oil emulsion, or mousse. Based on the 33 stations taken near the leaking wellhead, there was no indication of large-scale impacts of the oil on O2 levels during the first 35 days of the spill. The largest changes observed by the sensor were about 0.3 mL/L, which at this time, we do not believe are true O2 signals. If such a decrease occurred in the O2 minimum layer at 400 m with concentrations of about 2.7 mL/L, then the values would still be above what is generally considered hypoxic (1.4 mL/L or 2.0 mg/L). We therefore do not believe that the threat of large-scale hypoxia as a consequence of [microbial] oxidation near the wellhead at this time is a likely occurrence. However, simple calculations using the higher estimates (6/10/2010) for the amount of oil released of 1.3 million gallons/day suggest that O2 levels could decrease approximately 10% in the deep water if a significant fraction of oil remains subsurface and the rate of dispersion of the oil is low."--Executive summary. It updates earlier report: Joint Analysis Group (JAG). Review of R/V Brooks McCall Data to Examine Subsurface Oil. June 2010: http://www.noaa.gov/sciencemissions/PDFs/JAG_Report_1_BrooksMcCall_Final_June20.pdf.