Influence of black carbon and chemical planarity on bioavailability of sediment‐associated contaminants

Abstract

Black carbon (BC) and chemical properties may play a significant role in defining the bioavailability of hydrophobic organic compounds (HOCs) in sediment. In the current study, bioavailability of four HOCs with differing planarity was determined in sediments amended with two types of BC (soot and charcoal) at different concentrations by matrix solid-phase microextraction (matrix-SPME) and bioaccumulation testing using the freshwater oligochaete Lumbriculus variegatus. Furthermore, the applicability of the matrix-SPME method to bioavailability estimation in BC-amended sediment was tested. The charcoal treatment significantly reduced the bioaccumulation of the planar compounds (3,3',4,4'-tetrachlorobiphenyl and benzo[a]pyrene) in L. variegatus, and the matrix-SPME method showed a similar trend as contaminant bioaccumulation in L. variegatus. Conversely, manipulation of sediment with soot had no effect or slightly increased bioavailability of the planar compounds in both bioaccumulation and matrix-SPME tests. Little if any affect was noted in bioavailability of the nonplanar compounds (2,2',4,4',5,5'-hexachlorobiphenyl and permethrin) with the soot and charcoal amendments. Results showed that the role of BC in defining bioavailability of HOCs depends not only on the type and concentrations of BC present, but also the planarity of the HOCs.

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

“…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. In contrast, previous studies with spiked sediment showed BC significantly reduced the bioavailability of planar compounds, like benzo[a]pyrene, but had little effect on non-planar compounds, like permethrin (Pehkonen et al, 2010;Yang et al, 2009). The discrepancy among these studies may be due to the difference in OC types and sediment aging time.…”

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

“…21 Conversely, other studies have compared C f to chemical residues in organisms at the completion of exposure when the fiber and the organism have reached equilibrium and steady state, respectively. 3,6,22,23,31 Due to the different uptake rates for the fibers and organisms, relationships established at equilibrium are more likely to be consistent. Nevertheless, a longer exposure time and serial sampling were usually required to ensure equilibrium conditions.…”

“…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.…”

Methods to assess bioavailability of hydrophobic organic contaminants: Principles, operations, and limitations

“…For example, carbonaceous materials in sediments or soils are considered super sorbents for HOCs and have the ability to markedly alter the bioavailability of HOCs (Cornelissen et al, 2005). The effect of different types of black carbon on the bioavailability of HOCs has been investigated with the aid of disposable SPME fibers (Conder and La Point, 2005; Jonker et al, 2007; Pehkonen et al, 2010; Yang et al, 2009ab). In the case of carbon nanomaterials, the availability of HOCs has also been found to correlate closely with C free measured by SPME fibers (Cui et al, 2011, Hu et al, 2008), but exceptions exist.…”