It seems there is finally some good news coming out of the Gulf of Mexico.
After 170 days, the leaking oil well — nearly a mile under water — was finally plugged with mud. Officials say it means an end to the long spill. As BP stated in a news release:
“Pumping of heavy drilling mud into the well from vessels on the surface began at 1500 CDT on August 3, 2010 and was stopped after about eight hours of pumping. The well is now being monitored, per the agreed procedure, to ensure it remains static. Further pumping of mud may or may not be required depending on results observed during monitoring…
“A relief well remains the ultimate solution to kill and permanently cement the well. The first relief well, which started May 2, has set its final 9 7/8-inch casing. Operations on the relief wells are suspended during static kill operations. Depending upon weather conditions, mid-August is the current estimate of the most likely date by which the first relief well will intercept the Macondo well annulus, and kill and cement operations commence.”
If the spewing has indeed stopped for good, discussions about
the fate of the contamination and restoration of the ecosystem have
some real meaning. A report issued
this morning by the National Oceanic and Atmospheric
Administration starts to put the issue into perspective.
According to the report, about 25 percent of the 4.9 million
(205 million gallons) released were removed by skimming, burning or
direct recovery at the wellhead. Another 25 percent either
evaporated or dissolved. Another 24 percent was dispersed as tiny
droplets — either naturally or by the use of chemicals.
“The residual amount — just over one quarter (26%) — is either on or just below the surface as light sheen and weathered tar balls, has washed ashore or been collected from the shore, or is buried in sand and sediments,” the report concludes.
News reports that I read this morning — including a story by Justin Gillis of the New York Times — makes the point that the 26-percent residual is the amount that can still cause harm. Certainly, that 1.25 million barrels of “residual” oil is no small amount. But I’d like to hear more about the portion that has “dissolved,” along with the 24 percent still floating around as tiny droplets — including large “diffuse clouds” between 3,300 and 4,300 feet deep.
More studies are needed, but NOAA officials seem optimistic that the dispersed oil will biodegrade fairly rapidly.
Besides the fish, birds and mammals already killed (Fish and Wildlife Collection Report, PDF 99 kb), questions about the food web remain unanswered. Jane Lubchenco, NOAA’s top official, said one of the biggest questions is how much damage was done to the eggs and larvae of marine organisms needed to produce a new generation of sea creatures. Answers may not be clear for a year or more, she said.
On a slightly different topic, researchers reported yesterday that the Gulf’s “dead zone” is among the largest in history — stretching out 7,722 miles, slightly smaller than the state of New Jersey, according to reporter Allison Winter of Greenwire.
She quoted Nancy Rabalais, who leads the annual dead-zone survey, as saying the oil spill may or may not have contributed to the problem: “It would be difficult to link conditions seen this summer with oil from the BP spill, in either a positive or a negative way.”
Nutrients that flow down the Mississippi River from agricultural fertilizers and other sources are clearly identified as a contributor to the problem. Nitrogen, for example, triggers the growth of plankton, which die, sink and decompose. Bacteria involved in decomposition tend to suck up available oxygen.
With relation to the oil spill, bacteria will use up oxygen as they break down oil in the water column, but the effects in the Gulf of Mexico are widely disputed, as described in a story by Amanda Mascarelli in Nature News. Obviously, more studies are needed on this front.
Also this week, the Environmental Protection Agency issued a report on the toxicity of dispersants, finding that eight dispersants have similar toxicities and that “dispersant-oil mixtures are generally no more toxic to the aquatic test species than oil alone.”
As for worries that the oil will hit the Florida Keys or the East Coast, the Obama administration is now downplaying that threat. In a story today, reporter Mathew Daly of the Associated Press quoted White House Press Secretary Robert Gibbs as saying that the oil is unlikely to be picked up by the Loop Current and carried around the coast of Florida:
“I think it is fairly safe to say that because of the environmental effects of Mother Nature, the warmer waters of the Gulf and the federal response, that many of the doomsday scenarios that we talked about and repeated a lot have not and will not come to fruition.”
See NOAA’s report, which concludes, “Given current conditions, Southern Florida, the Florida Keys and the East Coast of the United States are not likely to experience any effects from the remaining oil on the surface of the Gulf.”
Doomsday or not, plenty of scientists and environmental activists remain worried, not only about the damage done to date but also about the ongoing effects of petroleum compounds on the Gulf’s rich ecosystem.