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Bioaccumulation of highly hydrophobic chemicals by Lumbriculus variegatus
Citation:
Burkhard, L., T. Lahren, T. Highland, R. Hockett, Dave Mount, AND T. Norberg-King. Bioaccumulation of highly hydrophobic chemicals by Lumbriculus variegatus. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY. Springer, New York, NY, 76(1):129-141, (2019). https://doi.org/10.1007/s00244-018-0554-6
Impact/Purpose:
For methodologically challenging compounds with large log KOWs (i.e., > 10), measured biota sediment accumulation factors (BSAFs), chemical uptake rates, and chemical depuration rates are limited for benthic invertebrates. The paper reports measured values for Lumbriculus variegatus for chemicals with estimated log KOWs extending up to 18.9. The measured BSAFs are orders of magnitude larger than those predicted using standard food web models, and dietary studies were recommended to improve the dietary assimilation efficiency sub-model within the standard food web models.
Description:
Assessments of the environmental behavior of highly hydrophobic nonionic organic chemicals have large uncertainties because the models used to predict their behavior were parameterized using training sets of chemicals with much lower hydrophobicities. Bioaccumulation of a few highly hydrophobic nonionic organic chemicals by Lumbriculus variegatus from contaminated sediments have been reported, and the measured and model predicted biota-sediment accumulation factors (BSAFs) differ by orders of magnitude. In the current study, sediment bioaccumulation tests with L. variegatus were performed on sediments dosed with chemicals having n-octanol/water partition coefficients (KOWs) larger than the highly hydrophobic chemicals studied to date. Steady-state BSAFs (kg organic carbon/kg lipid) of 0.0087, 0.012, and 0.0052 were measured for tetradecachloro-p-terphenyl, tetradecachloro-m-terphenyl, and octadecachloro-p-quaterphenyl, respectively. Predicted BSAFs using the Arnot-Gobas model were much smaller, i.e., 1.82E-06, 1.82E-06, and 4.00E-11, respectively, using estimated log KOWs of 14.23, 14.23, and 18.89 from EPISuite software. Examination of the Arnot-Gobas model suggests that the sub-model for dietary assimilation efficiency needs adjustment for chemicals with log KOWs exceeding 10, and dietary studies were recommended for highly hydrophobic chemicals to enable sub-model improvements.
