Accumulation and depuration of sediment-sorbed C12- and C16-polychlorinated alkanes by oligochaetes (Lumbriculus variegatus)

Oligochaetes (Lumbriculus variegatus) were exposed to sediment spiked with four 14C-polychlorinated alkanes (PCAs) (C12H20Cl6 [56% Cl by weight], C12H16,Cl10[69% Cl],C16H31Cl3[35%Cl], and C16H21Cl13 69% Cl]) to measure bioaccumulation parameters and biotransformation. Chlorinated paraffins are industrial products that consist of thousands of different PCAs. Chlorinated paraffins arc hydrophobic (log octanol-water partition coefficients (K=s] > 5.0) and are reported to have relatively high concentrations in sediment compared with other persistent organochlorines; however, no data exist on their bioavailability from sediment. The PCAs C12H20Cl6, C12H16Cl10, and C16H31Cl3 were readily available to sediment-ingesting oligochaetes, whereas C 16H21Cl13 had lower bioavailability. Uptake rates of the C12-PCAs were greater than the C16-PCAs, but half-lives (t1/2s) were greater for the C16-PCAs (t1/2 = 30-33 d) than for the C12-PCAs (t1/2 = 12-14 d). Biota-sediment accumulation factors were >1 for C12H20Cl6,C12H16Cl10,, and C16H31Cl3, but