ACCUMULATION AND DEPURATION OF SEDIMENT-SORBED C-12-POLYCHLORINATED AND C-16-POLYCHLORINATED ALKANES BY OLIGOCHAETES (LUMBRICULUS-VARIEGATUS)

Oligochaetes (Lumbriculus variegatus) were exposed to sediment spiked with four C-14-polychlorinated alkanes (PCAs) (C12H20Cl6 [56% Cl by we ight], C12H16Cl10 [69% Cl], C16H31Cl3 [35% Cl], and C16H21Cl13 [69% CI ]) to measure bioaccumulation parameters and biotransformation. Chlori nated paraffins are industrial products that consist of thousandsof di fferent PCAs. Chlorinated paraffins are hydrophobic (log octanol-water partition coefficients [K(ow)s] > 5.0) and are reported to have relat ively high concentrations in sediment compared with other persistent o rganochlorines; however, no data exist on their bioavailability from s ediment. The PCAs C12H20Cl6, C12H16Cl10, and C16H31Cl3 were readily av ailable to sediment-ingesting oligochaetes, whereas C16H21Cl13 had low er bioavailability. Uptake rates of the C-12-PCAs were greater than th e C-16-PCAs, but half-lives (t(1/2)s) were greater for the C-16-PCAs ( t(1/2) = 30-33 d) than for the C-12-PCAs (t(1/2) = 12-14 d). Biota-sed iment accumulation factors were >1 for C12H20Cl6, C12H16Cl10, and C16H 31Cl3, but <1 for C16H21Cl13. Comparison of toluene-extractable and -n onextractable C-14 suggest that PCAs were biotransformed in aerobic se diments and by oligochaetes, and that the susceptibility to degradatio n in sediments decreases with increasing chlorine content. The relativ e abundance of individual PCAs may differ between sediment and benthic invertebrates because of differences in the bioaccumulation and degra dation of PCAs of varying carbon chain length and chlorine content.