Rust-colored oil sullies a beach in Dauphin Island, Alabama, on June 2, fewer than two months after the Gulf oil spill began.
A year later, this beach and others hard-hit in Florida and Alabama are largely oil-free—though some shores outside the public eye remain contaminated, scientists say. (Get more Gulf oil spill anniversary news.)
Since June, coastal geologist Ping Wang and his team have been regularly monitoring blackened beaches from Panama City west to Dauphin Island (see map). By February, the scientists could only detect oil via fluorescent light. (See pictures of glowing oil taken in July.)
"If you make a sand castle, you won't really see the physical form of oil that can be identified with the naked eye," said Wang, of the University of South Florida (USF) in Tampa.
Markus Huettel, who has been surveying beaches in Pensacola, Florida, monthly, also found that much of the oil has broken down—but he noted that some of the tougher components, such as asphaltenes and resins, will be degraded at a much slower pace.
"It's not that after one year everything is gone," cautioned Huettel, a biological oceanographer at Florida State University (FSU) in Tallahassee. "That's just not possible."