Distribution and weathering of crude oil residues on shorelines 18 years after the Exxon Valdez spill.

In 2007, a systematic study was conducted to evaluate the form and location of residues of oil buried on Prince William Sound (PWS) shorelines, 18 years after the 1989 Exxon Valdez Oil Spill (EVOS). We took 678 sediment samples from 22 sites that were most heavily oiled in 1989 and known to contain the heaviest subsurface oil (SSO) deposits based on multiple studies conducted since 2001. An additional 66 samples were taken from two sites, both heavily oiled in 1989 and known to be active otter foraging sites.