Factors Affecting the Bioavailability of Hexachlorobiphenyls to Benthic Organisms

Abstract

The purpose of this study was to simultaneously evaluate several key factors which potentially affect the accumulation of hydrophobic pollutant compounds in sediment by benthic organisms. These factors were: (1) organic carbon content of the sediment; (2) equilibration time of the pollutant with the sediment; and (3) feeding strategies of the organism. [14C-U]2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) was equilibrated with sediments from Narragansett Bay, RI containing either 4 or 2% total organic carbon for periods of either one or four weeks. Biological availability of the compound was assessed by following the kinetics of HCBP uptake into either the omnivorous deposit feeding polychaete Nephtys incisa or the deposit feeding bivalve Yoldia limatula exposed to bedded sediment. In an attempt to normalize bioaccumulation data for differences in the lipophilic reservoirs between sediment and organism, an apparent preference factor (APF) was calculated comparing body burdens normalized to % lipid with sediment concentrations normalized to % total organic carbon (TOC) APF = (HCBPs/$TOC)/(HCBPo/%lipid) For both organisms, APF reached a constant value within 20 days. Length of isotope incubation with sediment had no observable effect on either the rate of approach to a constant APF or the value of APF reached. Even after normalizing with the preference factor calculation, significant differences were still evident between bioaccumulation from the two sediment types and between bioaccumulation from the same sediment by Yoldia and Nephtys. These data indicate that in addition to the influence of sediment TOC and lipid content of the organism, intrinsic properties of sediment and biological properties of the organism influence the transfer and bioaccumulation of hydrophobic compounds.

TOXICOKINETICS OF SEDIMENT-SORBED BENZO[a]PYRENE AND HEXACHLOROBIPHENYL USING THE FRESHWATER INVERTEBRATES HYALELLA AZTECA, CHIRONOMUS TENTANS, AND LUMBRICULUS VARIEGATUS

“…Early studies using HCBP and BaP did not reveal changes in bioavailability with increased aging times up to 150 d [4,5,7,25]. The results of the current study show that changes in bioavailability due to long-term sediment aging can occur, but these changes may be chemical specific and organism de- pendent.…”

Bioaccumulation of tetrachlorobiphenyl and hexachlorobiphenyl congeners by Yoldia limatula and Nephtys incisa from bedded sediments: Effects of sediment‐ and animal‐related parameters

“…The sediments were homogenized on a roller mill for 1 week prior to analyses for sediment characteristics and spiking with [ 14 C]chlorobiphenyls. Sediment slurries were equilibrated with the isotope for 7 or 30 d as described in McElroy and Means [19]…”

“…The centrifuged sediments were resuspended, homogenized, and sonicated with pesticide grade ACN. The suspension was subsampled (approximately 2.5–3.0 g dry weight) and extracted as described in McElroy and Means [19].…”

“… Research in a number of laboratories has suggested that predictive bioaccumulation models can be used to estimate exposure of benthic organisms from sediments [11,18,19]. However, results from further research in our laboratory (J.C. Means and A.E.…”

“…The bioaccumulation of PCBs or other neutral hydrophobic organic compounds from sediment has been hypothesized to be controlled in part by sediment/water partitioning [11,18– 20]. Hydrophobic compounds are strongly sorbed to sediments, exhibiting high sediment/water partition coefficients, which have been shown to be highly correlated to sediment organic carbon contents [21].…”