Understanding chemical exposure in sediment contact tests for improved effect extrapolation from laboratory to field

这一研究项目的目标是弥合实验室和实地在化学品暴露和对底栖生物的毒性方面的差距。在这项工作中，我们开发了实验和计算方法，以更好地了解实验室毒性测试中测试生物的实际化学暴露。建立了一个基于力学的质量传输模型，该模型考虑了化学物质在尖峰沉积物暴露系统中的扩散、吸附、稀释和胶体促进的传输。该模型成功地再现了实验浓度数据，并用于定量估计化学物质、沉积物和系统性质对化学物质质量分布的影响。模型与实验结果的比较表明，溶解有机物(DOM)在疏水化学物质的传输中起着至关重要的作用。此外，还开发和优化了使用聚合物网的被动剂量方法，以建立一致的曝光条件。用一组不同性质的化学品进行的毒性测试证明了该方法的稳健性、可重复性和适用性。用建立的方法证实了水中DOM对疏水化学物质对底栖无脊椎动物毒性的影响。结果表明，DOM具有重要作用，在评价底栖生物毒性时应予以考虑。

The goal of this research project was to bridge the gap between the laboratory and the field with respect to chemical exposure and toxicity to benthic organisms. In this work, we developed both experimental and computational approaches to better understand the actual chemical exposure of test organisms in laboratory toxicity testing. A mechanistically based mass transport model was established that accounted for diffusion, sorption, dilution, and colloid-facilitated transport of chemicals in the spiked-sediment exposure system. The model successfully reproduced experimental concentration data and was used to quantitatively estimate the influences of chemical, sediment, and system properties on the mass distributions of chemicals. Comparison of the model and experimental results indicated a crucial role of dissolved organic matter (DOM) in the transport of hydrophobic chemicals. In addition, the passive dosing method using polymer meshes was developed and optimized to set up a consistent exposure condition. Toxicity tests with a set of chemicals with varying properties proved the robustness, repeatability, and applicability of the method. The influences of DOM in water on the toxicity of hydrophobic chemicals to a benthic invertebrate species were confirmed using the developed method. The result suggests that DOM plays an important role and should be considered when assessing toxicity to benthic organisms.