Predicting bioaccumulation potential: a test of a fugacity-based model

Clams (Macoma nasuta) from an unpolluted site in Yaquina Bay, Oregon were exposed in the laboratory for 28 days to 6 field-contaminated sediments (treatments) which varied widely in concentration of 10 organic pollutants. Mean accumulation factors (AF = (concentration in tissue/lipid, %/100)/(concentration in sediment/total organic carbon, %/100] of 8 neutral organic compounds (DDE [p,p'], 2,2',3,5'6-pentachlorobiphenyl, 2,3',4,4',5-pentachlorobiphenyl, Aroclor 1254, pyrene, chrysene, benzo[a]pyrene, benzo [b, (k)]fluoranthene) were homogeneous across treatments. Statistically significant differences were detected between some treatment AFs for DDD [p, p'] and benz[a]anthracene, and between some chemicals within treatments (experimentwise alpha = 0.05). Accumulation factors were less than 2 and less variable in highly polluted, organically enriched sediments (total organic carbon greater than or equal to 3.69 +/- 0.044%), but sometimes exceeded 2 in clams exposed to surficial (0-2 cm deep) sediments with low pollutant concentration and low organic carbon content (less than or equal to 0.86 +/- 0.037%). These results suggest that the AF model may provide reasonable estimates of bioaccumulation potential of hydrophobic neutral organic compounds in organically enriched, polluted sediments.