Consistency of PAH concentrations in fish, mussels, and water following the Exxon Valdez oil spill

A study was undertaken to determine whether elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) found in the tissues of pink salmon fry (Oncorhynchus gorbuscha) and mussels (Mytilus trossulus) collected in Prince William Sound, Alaska, after the Exxon Valdez oil spill were consistent with direct measurements of PAHs in water samples. This was accomplished by using published, laboratory derived bioconcentration (BCF) equations to estimate time-integrated PAH concentrations of the water in which the organisms lived. The resulting estimates of water PAHs compare within a factor of 2 to 5 with actual water measurements and show similar trends with time. Estimates based on salmon tissue agreed most closely with direct water measurements. The fish appear to accumulate PAH from the dissolved phase. For unoiled areas, water estimates based on mussel tissue agree with direct water measurements. However, for the spill path, water estimates based on mussel tissue are higher than direct water measurements. This is thought to result from the accumulation of small oil droplets or oiled sediment particles by filter-feeding mussels, something not done by the fish. Results of this study may be useful to mussel watch monitoring programs and ecological risk assessments.