Scientists vehemently disagreed with the brief report issued by the federal government on August 4 that some interpreted as evidence that most of the oil spilled from BP’s Macondo well was…gone. Researchers at the University of Georgia issued their own report yesterday, claiming that nearly 80% of the oil spilled remains in the ecosystem, subject to evaporation and biodegradation but at unknown rates, meanwhile doing damage in a variety of different ways.
And natural gas, mostly methane, was released in great quantities during this spill. Some scientists have estimated that as much as 40% of the flow from the Macondo well was natural gas, mostly methane (CH4) that dissolved rather than floating to the surface and escaping into the atmosphere. At 80 cubic meters of methane per barrel of oil, with a total spill of 4.1 million barrels (172 million gallons) of oil, we calculate 328 million cubic meters – 11.6 billion cubic feet (BCF) – of methane were injected into the Gulf.
Researchers from Texas A&M University, the University of Georgia, and the University of California – Santa Barbara have measured levels of dissolved methane thousands of times above normal, thousands of feet below the surface. The microbial degradation of methane will consume oxygen from the water, possibly slowing biodegradation of the oil, particularly at deeper levels, and leading to the formation of additional oxygen-deficient dead zones devoid of fish, marine mammals, and much of the typical Gulf fauna.
Dr. Ian MacDonald of Florida State University will testify to Congress about this and the lingering impacts of this spill tomorrow morning. You can download his testimony here. A preview:
The Unified Command has made no mention of this gas, but it should not be ignored. Because the discharge occurred at 5000 ft depth, all the material rising toward the surface or drifting in subsurface plumes is in the ocean for hours, days, or months and can have a significant chemical and biological effect. So the hydrocarbon gas meets the OPA definition of “discharged.” The hydrocarbon gas is highly soluble in the deep, cold waters of the Gulf. Based on previous measurements, much of the gas released at depth will dissolve before it reaches the surface. Microbes degrading this material will compete for nutrients (like oxygen) with those attacking oil and will significantly affect the overall degradation process held to be so important by NOAA and DOI. Fish exposed to concentrated methane have exhibited mortality and neurological damage. The hydrocarbon gas was a major component of the total pollution load discharged from the BP well.