Assessing the risk of metal-contaminated sediments under disturbed conditions is challenging due to the lack of methods that capture instant changes in metal bioavailability. Existing approaches provide inadequate understandings of the processes regulating metal bioavailability under nonequilibrium conditions. Experiments were conducted to improve our understanding of the metal bioavailability dynamics induced by sediment resuspension and subsequent redeposition (reequilibration). An isotopically modified bioassay, a novel stable isotope tracing technique, was used to measure metal bioavailability (assimilation rates) to clams within short time windows. Changes in metal partitioning were characterized by porewater analysis using in situ extraction and the diffusive gradients in thin-films technique. Results showed that sediment resuspension released metals into porewater, while reequilibration scavenged metals from the porewater. The assimilation rates of Ni, Cu, and Pb increased with the resuspension time, aligning with increasing porewater concentrations. Unexpectedly, during reequilibration, the metal assimilation rates did not decrease. The discrepancies between bioavailability to the clam and porewater extrapolations may be due to differing sustained conditions of metals in sediments. Overall, this study unveils the metal bioavailability dynamics in nonequilibrium sediments, which could not be accurately predicted relying solely on porewater analysis. Incorporating rapid bioassays to determine bioavailability offers a valuable tool for robust ecological risk assessment.

中文翻译：

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沉积物芭蕾：揭示再悬浮和再平衡后沉积物中金属生物利用度的动态变化


由于缺乏捕获金属生物利用度即时变化的方法，因此在受干扰条件下评估金属污染沉积物的风险具有挑战性。现有方法对非平衡条件下调节金属生物利用度的过程没有提供足够的理解。进行了实验以提高我们对沉积物再悬浮和随后的再沉积 （再平衡） 诱导的金属生物利用度动力学的理解。同位素修饰的生物测定法，一种新型稳定同位素示踪技术，用于在短时间内测量金属对蛤蜊的生物利用度（同化率）。通过使用原位提取的孔隙水分析和薄膜中的扩散梯度技术来表征金属分配的变化。结果表明，沉积物再悬浮将金属释放到孔隙水中，而再平衡从孔隙水中清除金属。Ni 、 Cu 和 Pb 的同化速率随着再悬浮时间的增加而增加，与孔隙水浓度的增加一致。出乎意料的是，在再平衡过程中，金属同化率并没有降低。蛤蜊的生物利用度和孔隙水外推之间的差异可能是由于沉积物中金属的持续条件不同。总体而言，本研究揭示了非平衡沉积物中的金属生物利用度动态，仅依靠孔隙水分析无法准确预测。结合快速生物测定来确定生物利用度为稳健的生态风险评估提供了有价值的工具。