利用时间—反应法研究松花江典型污染物脉冲式暴露的生态毒理效应

Traditional standard laboratory toxicity tests performing at constant exposure concentrations have made it possible to study and develop water quality criteria. Yet, such classical methods rather unspecifically investigate the toxicity on time-varying exposures. Due to this limitation, traditional toxicity tests have so far almost exclusively been carried out in assessing the effects of realistic time-varying exposures from measurements made under constant exposure conditions..This research based on time - response approach was designed to characterize the ecotoxicology effects of pulsed exposures of typical pollutant （heavy metal and nitroaromatic compounds） in Songhua River on the aquatic sensitivity species, in which the effects of pulsed length (duration), pulsed magnitude (concentration), and the interval (recovery time) between pulses were characterized by static test, static-renewal test, flow-through test and elutriate test..The purpose of this study was to use quantitative survival-time approach employing time-response model based threshold damage test methods to examine latent effect and complete recovery time on a broad suite of endpoints of the aquatic sensitivity species to sequential pulsed and fluctuating typical pollutant concentrations in Songhua River..According to the methods and procedures of surface water quality criteria established by U.S. EPA, the toxicity data pulsed typical pollutants exposures on aquatic species existing widely in the Songhua River basin were selected. At the same time, species sensitivity distribution curves（SSD）based on Monte Carlo model and eco-toxicological models were employed to derive criteria maximum concentration（CMC）and criteria continuous concentration（CCC）of pulsed typical pollutant exposures for protection of aquatic life in the Songhua River basin. The results of this study wish to provide new technical approach and theory foundation for deriving national or local water quality criteria of different chemicals for protecting aquatic biota in China.

本项目利用时间-反应法相对于传统LD50/LC50 或ED50/EC50方法的优势，以东北地区第二松花江典型污染物-重金属、硝基芳烃化合物为研究对象，选择东北地区河流生态系统不同营养层次不同科属的多种敏感水生生物（藻、溞、鱼和底栖生物），通过静态试验、静态更新试验、流动试验、淘分试验，开展脉冲长度，脉冲大小，脉冲间隔都在变化的脉冲式暴露急性、慢性和特定生命阶段的致死、亚致死毒性效应和机理研究。本项目旨在一宽范围适宜端点体系下，应用存活时间法检测松花江流域典型污染物在各种相继脉冲和波动暴露下的延迟效应，定量预测完全恢复时间，阐明其恢复过程及脉冲暴露毒性机制。同时，采用蒙特卡罗构建物种敏感度分布曲线和生态毒理模型方法，预测脉冲式暴露下典型污染物重金属、硝基芳烃类化合物的水生生物急性基准浓度和慢性基准浓度，为东北区域特征水环境基准制定有效地提供适宜于脉冲式暴露的水污染防治的关键技术与理论依据。

本项目利用时间—反应法，选择生态系统不同营养层次敏感水生生物，以第二松花江典型污染物重金属、硝基芳烃为研究对象，开展脉冲长度，脉冲大小，脉冲间隔都在变化的生态毒理学效应研究。试验物种存活、生长和繁殖效应的研究表明，存活分析模型比传统的LC50法更加有益于暴露时间、延迟死亡和脉冲暴露效应的有效量化预测。生物暴露于多重脉冲相比于持续暴露可能更易于存活，连续脉冲之间的间隔（恢复时间）使得生物有时间通过净化和解毒过程从暴露中恢复过来。同时，重金属和硝基芳烃暴露后发生了不同的延迟效应，试验物种对重金属的恢复、清除可能是慢的，累积损伤导致明显的延后死亡率，即暴露生物的死亡比率高于经典LC50法预测的比率；而硝基甲苯有毒有机物的损伤机制可能导致累积性损害小，传统LC50值和完全LC50值之间没有显著差异。研究结果期望能够作为剂量/浓度-反应方法的理论补充，提供适宜于脉冲式暴露评价的有效技术途径。

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