ESTIMATION OF POLYCYCLIC AROMATIC HYDROCARBON CONCENTRATIONS IN THE WATER COLUMN BASED ON TISSUE RESIDUES IN MUSSELS AND SALMON - AN EQUILIBRIUM PARTITIONING APPROACH

Equilibrium partitioning was used to estimate concentrations of dissol ved polycyclic aromatic hydrocarbons (PAHs) in the water column from P AH residues in tissues of mussels and juvenile pink salmon collected f rom coastal marine waters affected by the Exxon Valdez oil spill. Esti mated concentrations were within factors of 2 to 5 for fish and 5 to 1 0 for mussels of average total dissolved and particulate PAHs measured in concurrent water samples. Temporal trends of estimated and measure d water-column PAH concentrations were comparable. Water-column PAH co ncentrations estimated from residues in tissues of mussels (Mytilus tr ossulus) were higher than estimates based on residues in tissues of ju venile pink salmon (Oncorhynchus gorbuscha). Possible reasons for this difference include seasonal variations in mussel lipid content, diffe rences in PAH uptake and depuration rates between fish and mussels, di fferences in how fish and mussels interact with particulate oil, and p ossible short exposure times for juvenile pink salmon. All of these fa ctors may play a role. In any event, estimates of dissolved PAHs in th e water column, based on PAH residues in either fish or mussel tissue, confirm that PAH concentrations generally did not exceed water qualit y standards for protection of marine life.