Bioavailability of lab‐contaminated and native polycyclic aromatic hydrocarbons to the amphipod Corophium volutator relates to chemical desorption

Abstract

In the present study, the relationship between bioavailability of polycyclic aromatic hydrocarbons (PAHs) to benthic amphipods and the PAH desorption kinetics was examined. To that end, field-contaminated sediment was treated in three different ways. One subsample had no addition of PAHs and contained native PAHs only. To a second subsample, six PAHs (phenanthrene, fluoranthene, anthracene, pyrene, benzo[b]fluoranthene, and benzo[k]fluoranthene) were added in the laboratory. Two of the PAHs were added at higher concentrations to a third subsample, serving as a control for concentration-dependent uptake. Marine amphipods (Corophium volutator) were exposed to the three subsamples for a maximum of 25 d and were subsequently analyzed. Desorption kinetics were determined for both the lab-contaminated and the native PAHs. The biota-to-sediment accumulation factor (BSAF) values of the individual native and lab-contaminated PAHs correlated well with the rapidly desorbing fraction (R2 = 0.76). The BSAFs were 1.4 to 3.3 higher for the lab-contaminated PAHs compared with the native PAHs, while the difference between the rapidly desorbing fractions was a factor of 1.1 to 1.8. The BSAFs of the lab-contaminated PAHs in the second and third subsample were equal, indicating concentration-independent accumulation. The results suggest that lab-contaminated PAHs are more available to amphipods than native PAHs and that differences in bioavailability of lab-contaminated and native PAHs to marine amphipods are related to differences in desorption behavior.

Direct Evidence of Sequestration in Sediments Affecting the Bioavailability of Hydrophobic Organic Chemicals to Benthic Deposit-Feeders

“…In the untreated sediment, we did not expect any significant redistribution between the rapidly and the slowly desorbing compartments during the 35-day exposure period of the oligochaetes, because of two reasons: (i) No significant changes in the rapidly desorbing fractions of PAHs were observed in the 137 weeks interval preceding the exposure (30). (ii) Rapidly desorbing fractions of PAHs in a lab-contaminated sediment were not altered by biota (24). In the treated sediment, however, the rapidly desorbing fraction in the treated sediment increased during the exposure period after the manipulation of the sediment.…”

“…The degradation of hydrophobic compounds was strongly related to the amount of chemical desorbing within a specified lapse of time (20)(21)(22). Lamoureux and Brownawell (23) showed a good correlation between the bioavailability of polycyclic aromatic hydrocarbons (PAHs) and linear alkylbenzenes in sediment cores to deposit-feeding clams and the fraction desorbing in 24 h. In a previous study, we demonstrated that 76% of the variability of BSAF of native and freshly added PAHs for deposit-feeding Corophia volutator could be explained by differences in the distribution over rapidly and slowly desorbing fractions (24).…”

“…Freeze-dried sediments were reflux extracted for 4 h with hexane and methanol (1:1) (29). One aliquot of the extract was prepared for analyses of PAHs as described elsewhere (24). A second aliquot for GC analysis was transferred to a glass column filled with 1.5 g of Al2O3 (7.5% water content) and 1.5 g of SiO2 (5% water content) and eluted with 30 mL of hexane.…”

“…Oligochaetes. Oligochaetes were extracted using Matrix Solid-Phase Dispersion (28) and prepared for PAH analyses as described earlier (24). In short, a syringe was filled with activated florisil and a homogenate of ground oligochaetes and octadecyl (C-18) and eluted with acetonitrile.…”

“…The rapidly desorbing fraction (Frap) as well as the BSAF were highly reduced in the treated sediment as compared with the untreated sediment, suggesting a relationship between these variables. We decided to investigate the relationship between BSAF and Frap as a measure of sequestration status, as earlier studies demonstrated that BSAF is highly correlated with Frap (24,30). In Figure 2, the BSAF of PAHs in the untreated and treated sediment are plotted versus the (average) rapidly desorbing fractions.…”