Colloid generation, stability, and transport are important processes that can significantly influence the fate and transport of nutrients and contaminants in environmental systems. Here, we critically review the existing literature on colloids in redox-dynamic environments and summarize the current state of knowledge regarding the mechanisms of colloid generation and the chemical controls over colloidal behavior in such environments. We also identify critical gaps, such as the lack of universally accepted cross-discipline definition and modeling infrastructure that hamper an in-depth understanding of colloid generation, behavior, and transport potential. We propose to go beyond a size-based operational definition of colloids and consider the functional differences between colloids and dissolved species. We argue that to predict colloidal transport in redox-dynamic environments, more empirical data are needed to parametrize and validate models. We propose that colloids are critical components of element budgets in redox-dynamic systems and must urgently be considered in field as well as lab experiments and reactive transport models. We intend to bring further clarity and openness in reporting colloidal measurements and fate to improve consistency. Additionally, we suggest a methodological toolbox for examining impacts of redox dynamics on colloids in field and lab experiments.

中文翻译：

---

批判性地审视氧化还原动态环境中胶体的生成、稳定性和传输：挑战和前景

胶体的生成、稳定性和运输是重要的过程，可以显着影响环境系统中营养物和污染物的命运和运输。在这里，我们批判性地回顾了有关氧化还原动态环境中胶体的现有文献，并总结了有关胶体生成机制和此类环境中胶体行为的化学控制的知识现状。我们还发现了关键的差距，例如缺乏普遍接受的跨学科定义和建模基础设施，这阻碍了对胶体生成、行为和运输潜力的深入了解。我们建议超越胶体基于尺寸的操作定义，并考虑胶体和溶解物质之间的功能差异。我们认为，为了预测氧化还原动态环境中的胶体传输，需要更多的经验数据来参数化和验证模型。我们认为胶体是氧化还原动力系统中元素预算的关键组成部分，必须在现场以及实验室实验和反应输运模型中紧急考虑。我们打算进一步提高胶体测量和结果报告的清晰度和开放性，以提高一致性。此外，我们建议使用一个方法工具箱来检查氧化还原动力学对现场和实验室实验中胶体的影响。