STP1124

    Effect of Variation in Sediment Composition on the Uptake Rate Coefficient for Selected PCB and PAH Congeners by the Amphipod, Diporeia sp.

    Published: Jan 1991


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    Abstract

    The exposure of benthic organisms to sediment-associated toxic organics is influenced by the sediment's organic carbon (OC) content because hydrophobic organic contaminants sorb to the organic and fine grain portions of sediments, and benthos ingest the OC associated with fine material. The effect of varying sediment composition, measured as the percent of combustible solids (CS), percent of OC, and percent of fine-grained material (FM) (the <63 μm fraction of the sediment), was examined by determining the accumulation of sediment-associated polychlorinated biphenyl and polycyclic aromatic hydrocarbon congeners by the Great Lakes amphipod, Diporeia sp. Prepared sediments (3 and 5% CS) and native sediment were dosed with pairs of contaminants: 3H-pyrene and 14C-2,5,2',5'-tetrachlorobiphenyl, and 3H-benzo(a)pyrene and 14C-2,4,5,2',4',5'-hexachlorobiphenyl. Additionally, someof the dosed 5% CS sediment was recombined with the coarse material to recreate a 2% CS sediment where the fine material had been dosed preferentially. The accumulation of the radiolabeled compounds was followed for 27 days, and the partitioning between sediment particles and interstitial water was measured at the end of the experiment. When uptake rate coefficients (Ks) and the depuration rate constants (Kd) were estimated, the Kd values were found to be similar to those previously measured in Diporeia. The Ks values from the native and fine labeled sediments (both approximately 2% CS) were similar. Ks values declined with increasing CS, OC, and FM. Correlations indicated that the percent of OC best accounted for the variation resulting from changes in the sediment composition for each compound, both for Ks and for sediment-interstitial water partitioning. As in previous studies, the partition coefficient between sediment and interstitial water did not account for the changes in the bioavailability between different classes of compounds. Higher partitioning and higher uptake rate coefficients were found for the chlorinated hydrocarbons than for the polycyclic aromatic hydrocarbons, even when the hydrophobicity of the contaminants was accounted for. A linear solvation energy quantitative structure activity model was useful for describing the differences in the uptake rate coefficients by accounting for the differences in the molecular characteristics of the two compound classes.

    Keywords:

    sediments, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, partition coefficients, bioaccumulation, Diporeia, sp., linear solvation energy model, QSAR


    Author Information:

    Landrum, PF
    Great Lakes Environmental Research Laboratory, NOAA, Ann Arbor, MI

    Faust, WR
    Great Lakes Environmental Research Laboratory, NOAA, Ann Arbor, MI


    Paper ID: STP23577S

    Committee/Subcommittee: E47.03

    DOI: 10.1520/STP23577S


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