College of Resources and Environment Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guizhou University, Guiyang 550025, China.
College of Resources and Environment Engineering, Key Laboratory of Karst Georesources and Environment, Ministry of Education, Guizhou University, Guiyang 550025, China; Guizhou Karst Environmental Ecosystems Observation and Research Station, Ministry of Education, Guizhou University, Guiyang 550025, China.
J Environ Sci (China). 2025 Mar;149:663-675. doi: 10.1016/j.jes.2024.02.015. Epub 2024 Mar 16.
Humic acid (HA), a principal constituent of natural organic matter (NOM), manifests ubiquitously across diverse ecosystems and can significantly influence the environmental behaviors of Cd(II) in aquatic systems. Previous studies on NOM-Cd(II) interactions have primarily focused on the immobilization of Cd(II) solids, but little is known about the colloidal stability of organically complexed Cd(II) particles in the environment. In this study, we investigated the formation of HA-Cd(II) colloids and quantified their aggregation, stability, and transport behaviors in a saturated porous media representative of typical subsurface conditions. Results from batch experiments indicated that the relative quantity of HA-Cd(II) colloids increased with increasing C/Cd molar ratio and that the carboxyl functional groups of HA dominated the stability of HA-Cd(II) colloids. The results of correlation analysis between particle size, critical aggregation concentration (CCC), and zeta potential indicated that both Derjaguin-Landau-Verwey-Overbeek (DLVO) and non-DLVO interactions contributed to the enhanced colloidal stability of HA-Cd(II) colloids. Column results further confirmed that the stable HA-Cd(II) colloid can transport fast in a saturated media composed of clean sand. Together, this study provides new knowledge of the colloidal behaviors of NOM-Cd(II) nanoparticles, which is important for better understanding the ultimate cycling of Cd(II) in aquatic systems.
腐殖酸（HA）是天然有机物（NOM）的主要成分，广泛存在于各种生态系统中，可显著影响水生系统中 Cd(II)的环境行为。先前关于 NOM-Cd(II)相互作用的研究主要集中在 Cd(II)固体的固定化上，但对于环境中有机络合 Cd(II)颗粒的胶体稳定性知之甚少。在这项研究中，我们研究了 HA-Cd(II)胶体的形成，并定量研究了它们在代表典型地下条件的饱和多孔介质中的聚集、稳定性和迁移行为。批实验结果表明，随着 C/Cd 摩尔比的增加，HA-Cd(II)胶体的相对数量增加，并且 HA 的羧基官能团主导 HA-Cd(II)胶体的稳定性。粒径、临界聚集浓度（CCC）和 ζ 电位之间相关性分析的结果表明，DLVO 和非-DLVO 相互作用都有助于增强 HA-Cd(II)胶体的胶体稳定性。柱实验结果进一步证实，稳定的 HA-Cd(II)胶体可以在由清洁砂组成的饱和介质中快速迁移。总之，这项研究提供了有关 NOM-Cd(II)纳米颗粒胶体行为的新知识，这对于更好地理解水生系统中 Cd(II)的最终循环非常重要。
