Bioaccumulation in fish (Cyprinodon variegatus) during rejuvenations of a thin active cap over field-aged PCB contaminated sediment: The effect of clean versus contaminated ongoing influx.

Repeated addition of activated carbon (AC) via the water column was applied to rejuvenate sorption capacity of thin AC-amended sand caps placed over polychlorinated biphenyl- (PCB) contaminated marine bed sediment receiving ongoing input of sediment (contaminated or clean) in mesocosms. Bioaccumulation of PCBs in sheepshead minnows (Cyprinodon variegatus) from bed sediment was reduced by repeated application of rejuvenating AC when the ongoing input was contaminated. However, when the input sediment was clean, the novel AC addition increased fish uptake of bedded PCBs in the first 60-days of the 90-day experiments. The 79 % increase of bedded PCB bioaccumulation in fish, for clean versus contaminated inputs, was statistically significant (p < 0.05) in experiments where the rejuvenating AC was applied. Equilibrium concentrations in low-density polyethylene (LDPE) passive samplers did not fully explain bioaccumulation. Field implications of this research include setting appropriate temporal expectations of this novel remediation strategy regarding the primary desired effect (i.e., PCB bioavailability reductions).