The contrasting roles of sedimentary plant‐derived carbon and black carbon on sediment‐spiked hydrophobic organic contaminant bioavailability to Diporeia species and Lumbriculus variegatus

Abstract

In bioavailability studies, the biota sediment accumulation factor (BSAF) is invoked to describe the thermodynamic partitioning of a hydrophobic organic contaminant (HOC) between the organism lipid and the organic carbon fraction of the sedimentary matrix and accounts for differences in bioavailability among sediments. Bioaccumulation experiments were performed with Lumbriculus variegatus and Diporeia species exposed in seven sediments dosed with 2,4,5,2',4',5'-hexachlorobiphenyl (HCBP) and benzo[a]pyrene (BaP) or pyrene (PY) and 3,4,3',4'-tetrachlorobiphenyl (TCBP). The BSAF values for the nonplanar HCBP were consistent with equilibrium partitioning theory (EQP) and averaged 2.87 for L. variegatus and 1.45 for Diporeia, while the BSAF values for the planar compounds (BaP, PY, TCBP) were generally lower than estimated from EQP (<1). Correcting the BSAF values of the planar compounds for enhanced sorption due to black carbon improved the BSAF values for L. variegatus, generally resulting in values consistent with EQP, but substantial variation remained for Diporeia. The BSAF values for the planar compounds showed significant positive correlations with plant-derived carbon in sediments (lignin and pigments) but were more consistent for L. variegatus than for Diporeia. These correlations imply that compounds sorbed to plant-derived carbon are more bioavailable since this material is more likely ingested providing a second exposure route.

Addition of contaminant bioavailability and species susceptibility to a sediment toxicity assessment: Application in an urban stream in China

“…These significant relationships indicated pyrethroids tended to bind to OC, and OC-normalization would reduce the concentration variation among different sediments, while BC was also involved in the sorption process. However, in addition to total OC content, the types of OC should also be taken into consideration for estimating bioavailability of contaminants (Cornelissen et al, 2005;Kukkonen et al, 2005). Fleming et al (1998) reported that different types of OC (peat or a-cellulose) significantly affected permethrin toxicity to Chironomus riparius at a constant OC content.…”

Chemical techniques for assessing bioavailability of sediment-associated contaminants: SPME versus Tenax extraction

“…2 Other sediment characteristics, however, such as particle size 3 and types of OC, e.g. black carbon and pigments, [4][5][6] can also play a critical role in the bioaccumulation of sediment-associated HOCs. As a result, simply normalizing HOC concentrations to sediment OC may not fully compensate for the differences among sediments.…”

Validation of Ontario's new laboratory‐based bioaccumulation methods with in situ field data

“…The present study, and work by others, suggests that these assumptions are not always valid [5,9,16,[29][30][31][32]. Indeed, it has been shown that different fractions of TOC, black carbon in particular, can enhance sorption and decrease bioavailability of contaminants, especially with planar compounds such as PAHs or PCDD/Fs [33][34][35]. However, BSAFs remains very useful for making these relative comparisons of bioaccumulation.…”