Biota-sediment Accumulation Factor Values Research Articles

Impaired growth in the polychaete Armandia brevis exposed to tributyltin in sediment

Juveniles of the opheliid polychaete, Armandia brevis, were exposed to sediment-associated tributyltin (TBT) for 42 days to evaluate toxicity and bioaccumulation. Growth in this species was inhibited in a dose–response fashion by increasing concentrations of TBT. Even though the biota–sediment accumulation factor (BSAF) for TBT declined for the higher sediment concentrations, the total butyltins in tissue increased over all sediment concentrations. At the highest sediment concentrations, polychaetes bioaccumulated less TBT than expected, which was most likely due to reduced uptake and continued metabolism of the parent compound. The less than expected BSAF values exhibited by animals at the exposure concentrations causing severe effects are an important finding for assessing responses in the field. It appears that severe biological effects can occur in long-term experiments without the expected high tissue concentrations; an observation likely explained by altered toxicokinetics. Analysis of variance determined the lowest observed effect concentration for growth to be 191 ng/g sediment dry wt. for 21 days of exposure and 101 ng/g sediment dry wt. at day 42, indicating that 21 days was insufficient for delineating the steady-state toxicity response. When based on regression analysis, the sediment concentration causing a 25% inhibition in growth at 42 days exposure was 93 ng/g dry wt. (total organic carbon=0.58%). A dose–response association was also determined for polychaete net weight and TBT in tissue. The tissue residue associated with a 25% reduction in growth was 2834 ng/g dry wt. at day 42. A comparison of these results with previous work indicates that juveniles are approximately three times more sensitive than adults to TBT exposure. The sediment concentrations affecting growth in this species are commonly found in urban waterways indicating potentially severe impacts for this and other sensitive species.

Toxicity and phototoxicity of mixtures of highly lipophilic PAH compounds in marine sediment: can the SigmaPAH model Be extrapolated?

The additivity of toxic units was tested using sediments contaminated with mixtures of highly lipophilic (log Kow > 4.5) parent and alkylated PAHs. The direct toxicity and photoinduced toxicity of these mixtures were examined in standard 10-day sediment toxicity tests using the infaunal amphipod Rhepoxinius abronius, with mortality and the survivors' ability to rebury as endpoints. Survivors of the initial 10-day tests were then exposed for 1 h to ultraviolet (UV) radiation and the results compared to initial (10-day) endpoints. Tissue residues and lipids were measured and biota-sediment accumulation factor (BSAF) values determined. The results indicated that the bioaccumulated contaminants were not initially toxic, however, they were highly phototoxic. Although the summed toxic units of these contaminants appeared to be nonadditive, additivity was not disproved as inaccuracies in extrapolating the Kow-LC50 QSAR or insufficient exposure duration might also have accounted for the observed results. Critical body residue (CBR) estimates for R. abronius were similar while BSAF values were much larger (10x) in comparison to other studies, which used amphipods and PAHs. The phototoxicity of mixtures of contaminants were similar to the phototoxicity of single contaminants when expressed on a molar basis, which suggests that phototoxicities may be roughly additive.

BIOACCUMULATION OF POLYCHLORINATED BIPHENYLS FROM SEDIMENTS TO AQUATIC INSECTS AND TREE SWALLOW EGGS AND NESTLINGS IN SAGINAW BAY, MICHIGAN, USA

Sediments in the Saginaw Bay region of the Great Lakes contain concentrations and polychlorinated biphenyls (PCBs) that may adversely affect biotic species in various trophic levels. In this study the authors collected and analyzed sediments, benthic invertebrates, tree swallow eggs, and nestlings to evaluate linkages between PCBs in sediments and at various trophic levels in the Saginaw River, Michigan, USA. Their results indicate that patterns of relative concentrations of PCB congeners change with trophic level, specifically from sediment to invertebrates and from tree swallow eggs to nestlings. However, if biota-sediment accumulation factor (BSAF) values are based on only the non- and mono-ortho-substituted PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEq), calculated BSAF values are close to those predicted by fugacity theory. The use of site-specific BSAF values and reference doses for toxic effects in wildlife can be used to derive sediment quality criteria (SQC) that are protective of wildlife at the top of the sediment-based food chain. The threshold concentration of TEq in sediments that would protect sensitive avian species at the same trophic level as tree swallows was calculated to be 1.5 {times} 10{sup {minus}1} TEq/g total organic carbon. Based on this value and the BSAF determined for tree swallow nestlings,more » the hazard quotient for sediments in this area was determined to be 0.7. This indicates that current concentrations of TEq due to PCB congeners in the sediments should be below the threshold for adverse effects on tree swallows. The uncertainty in the concentrations of PCB congeners in the sediments was approximately a factor of 2, which determined the degree of resolution that could be obtained from the observations made in this study.« less