ANCHORAGE, Alaska, Jan. 18 (UPI) -- Thousands of gallons of oil from Alaska's 1989 Exxon Valdez spill are trapped in compacted beach sediment, scientists said.
About 21,000 gallons of the 11 million gallons of oil spilled remain on beaches in Prince William Sound, The Anchorage Daily News reported Monday.
In the years after the massive spill, the oil degraded fairly quickly and then slowed. A new study shows the remaining oil has compacted and is impervious to dissipation, said Michel Boufadel, lead researcher of a $1.2 million study funded by the Exxon Valdez Oil Spill Trustee Council.
Proposals to remove residual oil from the beaches are still being negotiated with Exxon Mobil, which owned the damaged tanker Exxon Valdez.
Boufadel's study showed the beaches comprise an upper layer permeable to water, nutrients and oxygen and a lower layer not permeable to those elements, Boufadel said.
The oil is trapped in the lower layer, where Exxon contends it is not hurting the environment and doesn't require further cleanup, said Exxon contractor Paul Boehm.
Boufadel's work suggests otters, sea birds and other animals are still ingesting harmful amounts of oil when they forage for food.