Persistence of oiling in mussel beds after the Exxon Valdez oil spill

Persistence and weathering of Exxon Valdez oil in intertidal mussel (Mytilu s trossulus) beds in Prince William Sound (PWS) and along the Gulf of Alask a was monitored from 1992 to 1995. Beds with significant contamination incl uded most previously oiled areas in PWS, particularly within the Knight Isl and group and the Kenai Peninsula. In sediments, yearly mean concentrations of total petroleum hydrocarbons ranged from < 60 <mu>g/g in reference beds to 62,258 mug/g wet wt., or approximately 0 to 523 mug/g dry wt. total pol ynuclear aromatic hydrocarbons (TPAHs). In mussels, mean TPAH concentration s ranged up to 8.1 mug/g dry wt. Hydrocarbon concentrations declined signif icantly with time in some, but not all mussels and sediments, and should re ach background levels within three decades of the spill in most beds. In 19 95, mean hydrocarbon concentration was greater than twice background concen tration in sediments from 27 of 34 sites, and in mussels from 18 of 31 site s. (C) 2001 Elsevier Science Ltd. All rights reserved.