Using marine bioassays to classify the toxicity of Dutch harbor sediments.

A procedure was developed to assess contaminated marine sediments from Dutch harbors for possible adverse biological effects using three laboratory bioassays: A 10-d survival test with the amphipod Corophium volutator, a 14-d survival test with the heart urchin Echinocardium cordatum (adults), and the bioluminescence inhibition test with the bacterium Vibrio fischeri (Microtox solid phase test LSP]). Microtox results were mathematically corrected for the modifying influence of fine sediment particles. After a validation procedure on test performance and modifying factors, respectively, 81%, 99%, and 90% of the amphipod, heart urchin, and Microtox results were approved. Lower and upper threshold limits for biological effects were set at respectively 24 and 30% mortality for C. volutator, 27 and 35% mortality for E. cordatum, and 24 and 48 toxic units for the Microtox SP based on significant differences with control sediment and the performance of reference sediments. The bioassays clearly distinguished harbor sediments that give rise to acute effects and those that do not. Threshold limits for the amphipods, heart urchins, and bacteria were exceeded in, respectively, 9 to 17%, 33 to 40%, and 23 to 50% of the sediment samples. Highest effects were observed in sediments from the northerly harbors; there was significantly less response in sediments from the Delta Region and the port of Rotterdam (The Netherlands). The procedure outlined in this paper can be used for routine screening of contaminated dredged material that is proposed for open water disposal.

A toxicity identification evaluation of silty marine harbor sediments to characterize persistent and non-persistent constituents.

Sediment toxicity in silty marine harbor sediments is frequently dominated by ammonia or sulfide, leaving the adverse effects of persistent toxic substances unnoticed. To investigate the latter, we subjected interstitial water from three contaminated silty sediments to toxicity identification evaluation (TIE) phase I manipulations and tested for toxicity with four bioassays: the amphipod Corophium volutator (survival as an endpoint), the sea urchin Psammechinus miliaris (fertilization, embryo development) and the bacterium Vibrio fischeri (bioluminescence inhibition). The graduated pH manipulations identified the prominent toxicity of ammonia in the amphipod and sea urchin embryo tests, and also sulfide toxicity in the bacterium test. In two of the three samples tested with the amphipods, sea urchin embryos and bacteria, a small but significant reduction in interstitial water toxicity was achieved by removing persistent compounds through C(18) solid phase extraction. EDTA chelation resulted in a slight detoxification of the interstitial water for the amphipods and sea urchin embryos, but this was not related to any measured trace metals. Despite the presence of toxic levels of ammonia and sulfide in the harbor sediments, we established the adverse biological effects of persistent constituents by means of the TIE manipulations and in vivo interstitial water bioassays.

Using the dioxin receptor-CALUX in vitro bioassay to screen marine harbor sediments for compounds with a dioxin-like mode of action.

The presence of dioxin-like compounds in sediments from harbors and reference sites along the Dutch coast was investigated using the dioxin receptor-chemically activated luciferase gene expression (DR-CALUX) bioassay. The DR-CALUX response varied between 0.2 and 136 ng/kg dry weight expressed in units of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalency quotients (TEQ). The highest CALUX-TEQ values (> 50 ng TEQ/kg dry wt) were found in sediments from the center of the Port of Rotterdam and from the North Sea canal near Amsterdam. The DR-CALUX activity of harbor sediments was classified by setting guideline values. None of the 257 harbor sediment samples investigated exceeded the maximum value of 1,000 ng TEQ/ kg, while 94% of the samples fail the target value of 2 ng TEQ/kg. Threshold values (25 and 50 ng TEQ/kg) are intended as pass/ fail criteria for offshore disposal of dredged material and were exceeded in 12 and 3% of the samples, respectively. DR-CALUX response did not always match with contamination of polychlorinated biphenyls (PCBs) as determined in bulk sediments (sigma7-PCB ranging from < 1 to 456 microg/kg dry wt). Concentrations of planar PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated-dibenzofuranes (PCDFs), polybrominated biphenyls (PBBs), and polybrominated-diphenylethers (PBDEs) were determined in 20 selected sediment extracts. On average, PCDD/Fs explained 50% of the DR-CALUX activity and planar PCBs 6%. Further research is needed to elucidate the unexplained part of the DR-CALUX response. The DR-CALUX is a highly sensitive and reproducible bioassay that can usefully complement standard PCB analysis, improving the hazard assessment of the disposal of dredged material in the North Sea.

Bioaccumulation and toxicity of tributyltin to a burrowing heart urchin and an amphipod in spiked, silty marine sediments.

The presence of tributyltin (TBT) in silty sediments is regarded as a long-term threat to marine and estuarine environments due to its persistence. The bioaccumulation kinetics and toxicity of TBT in the deposit-feeding heart urchin Echinocardium cordatum was studied in silty sediment spiked with TBT and equilibrated prior to the 28-d exposure. An additional 10-d acute toxicity test was carried out with the burrowing amphipod Corophium volutator in the same sediment. Because E. cordatum has a low lipid content and apparently high elimination and metabolic rates, only a moderate degree of TBT bioaccumulation was observed, with biota-sediment accumulation factors (BASFs) of 0.09 to 0.21 (dry weight basis) and biota accumulation factors (BAFs) of 180 to 843 (wet weight basis). The lethal body residue in E. cordatum (soft tissue and skeleton) was 0.8 to 3.4 nmol TBT+ /g wet weight which, considering the differences in lipid content, is comparable to data on other taxonomic groups. For E. cordatum and C. volutator, the LC50s for pore water (222 and 329 ng Sn/L) were also close to reported values for aquatic and benthic organisms. The TBT concentrations in the pore water of the silty sediment were much lower than might be expected from the octanol-water partition coefficient. The measured sediment-water partitioning coefficient Kp was 8,700 L/kg dry weight. Consequently, toxicity was observed at a relatively high TBT concentration in the bulk sediment with LC50s for E. cordatum and C. volutator of 1,594 and 2,185 ng Sn/g dry weight, respectively. The results show that TBT is highly toxic to the benthic species investigated and sorption in the silty sediment strongly reduced the bioavailability of the compound.