Only 26 Percent of Spilled Oil Still Endures

Officials at the National Incident Command (NIC) announce the release of a new report, which details the faith of the oil that was spilled in the Gulf of Mexico starting April 20. Investigators from the cross-agency task force determined that only 26 percent of the crude can still be found as light sheens or weathered tar balls on or near the surface of the water. The remaining quantities have been removed, or have dispersed naturally, and part of this success is due to robust federal response efforts.

According to the new document (.pdf), about one quarter of the overall amount of oil was neutralized through burning, skimming, and direct recovery from the Deepwater Horizon wellhead. An additional 25 percent of the oil dissipated or evaporated naturally, and the remaining 24 percent dispersed naturally, or with “help” from federal emergency response teams. In addition to light sheens and tar balls, the remaining crude has also been buried in sediments and sand, or has washed up on shore. Important amounts of oil have already been collected from various locations.

“Response efforts to deal with the oil have been aggressive. As shown in the pie chart, response efforts were successful in addressing 33% of the spilled oil. This includes oil that was captured directly from the wellhead by the riser pipe insertion tube and top hat systems (17%), burning (5%), skimming (3%) and chemical dispersion (8%). Direct capture, burning and skimming remove the oil from the water entirely, while chemically dispersed oil remains in the water until it is biodegraded,” experts write in the new document.

Experts from NASA, the US National Oceanic and Atmospheric Administration (NOAA), the Department of the Interior (DOI), and the Environmental Protection Agency (EPA) worked together with colleagues from other agencies to produce the new Oil Budget Calculator. According to the Flow Rate Technical Group, more than 4.9 million barrels of oil have spilled into Gulf of Mexico waters. The Calculator is based on this number. Some 25 of the best scientists in the United States, both from the governmental and private sectors, contributed to verifying the Calculator.