| 英文摘要 |
Whole-sediment toxicity tests are increasing being used in ecological risk assessments of contaminants in sediments. In this project, we developed and evaluated two chronic toxicity tests in sediment to predict the sublethal effects of chemicals of potential concern (COPCs) on the sediment-dwelling organism (Hyalella azteca) and cobitidae (Paramisgurnus dabryanus). The first objective of this project was to review and summarize the newly published sediment toxicity tests literatures. The second was to measure the toxicity endpoints including variables tolerance in survival/ growth/reproduction of H. azteca and growth/fecundity of Paramisgurnus dabryanus exposed to formulated sediment. Furthermore, the addition of metal (copper) and polycyclic aromatic hydrocarbon (fluoranthene) to sediment were used to determine the cause-and-effect relationships in two tests. Our results showed two whole sediment chronic toxicity experiments with an amphipods (H. azteca ; 42-day exposure) and cobitidae (Paramisgurnus dabryanus; two months exposure) for measuring effects on survival/growth/reproduction was successfully developed. Our study observed that the amphipod survival was 80% which meet the minimum control survival for test acceptability under certain exposure condition (four time water renewal, 1mL of yeast/ wheatgrass /flake diet). Results of reproduction and growth data reported length >3.2mm/individual, weight >0.15 mg/individual and >2 young produced from our study also meet the existing methods published by U.S.EPA. In copper and fluoranthene spiked sediment toxicity tests, the LC50 for H. azteca was 62.56 mg Cu/kg based on the dose-response relationship. Significant growth (length and weight) differences were observed between the formulated sediment and experimental group at concentration of 200 mg/kg (p<0.05). There is no survival of H. azteca at concentration of 500 mg/kg. Furthermore, the survival of the H. azteca in fluoranthene spiked sediments was low and only 10-20% in control groups. The reason may related to the acetone residue in spiked solution used to dissolve the fluoranthene in the sediment. The frequency of water change and sediment renewal did not significantly influence the growth, survival, feed efficiency and condition factor of fish in the trials with the Paramisgurnus dabryanus. Moreover, our study observed that fertilization rate and growth performance of the P. dabryanus were suppressed by 100 mg Cu/kg and 200 mg Cu/kg in sediment, and 100 % mortality were found at concentration of 400 mg Cu/kg. Similarly, the significantly decreased fertilization rate of P. dabryanus was recorded in fish exposure to the sediment containing 100 mg/kg fluoranthene. The growth (length and weight), survival and condition factor of P. dabryanus were therefore inhibited at higher exposed concentration. The results proved the feasibility of using cobitidae in sediment toxicity test. Overall, the spiked-sediment toxicity tests provide additional data on the relative selecting and variability of sublethal endpoints in two sediment toxicity tests.
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