The hyporheic zone is a crucial ecohydrological interface that plays a substantial role in the biogeochemical activity of iron and its mediated pollutant conversion. It is significantly influenced by dissolved oxygen and temperature fluctuations, but the combined effects and mechanisms are unknown. In this study, the co-transport behavior of goethite colloid (Goe), aqueous Fe2+ and oxytetracycline (OTC) in groundwater discharge was simulated by column experiments. Our findings reveal that compared with room temperature (25 °C), the penetration rates of these compounds were generally promoted (0.1–7.0 % Goe, 14.1–43.1 % Fe2+, 0–19.6 % OTC) at low temperature (10 °C) but inhibited (0–5.0 % Goe, 0–51.0 % Fe2+, 0–3.8 % OTC) at high temperature (35 °C). At room temperature (25 °C), only 5 % of the Goe can penetrate the triadic transport system, where the Fe-OTC complex decreased the Zeta potential of Goe, hence improving its transport capacity. Compared with the penetration of individual Fe2+, the Fe2+ transport was increased by 13.2 % due to the promoting effect of OTC on Fe redox cycling, whereas the electron transfer effect between Goe and Fe2+ inhibited the transport by 46.6 %. The impact of μg/L OTC on the migration of Fe and Goe was dramatically diminished compared to the mg/L level. OTC was eliminated mainly by complex internal oxidation with Fe, weak adsorption, chemisorption, and hydroxyl degradation effects, but these were diminished at low temperatures while intensified at high temperatures. This study provides a deeper understanding of the intricate mechanisms of Fe and antibiotic transport in hyporheic zones, highlighting the significant roles of temperature and chemical interactions, particularly during seasonal changes.

中文翻译：

---

针铁矿、Fe2+ 和抗生素在低流区的温度依赖性共转运行为


低流带是一个重要的生态水文界面，在铁的生物地球化学活动及其介导的污染物转化中起着重要作用。它受溶解氧和温度波动的显著影响，但综合效应和机制尚不清楚。本研究通过柱实验模拟了针铁矿胶体 （Goe）、Fe2+ 水和土霉素 （OTC） 在地下水排放中的共输运行为。我们的研究结果表明，与室温 （25 °C） 相比，这些化合物的渗透速率在低温 （10 °C） 下通常较高 （0.1-7.0 % Goe， 14.1-43.1 % Fe2+， 0-19.6 % OTC），但在高温 （35 °C） 下被抑制 （0-5.0 % Goe， 0-51.0 % Fe2+， 0-3.8 % OTC）。在室温 （25 °C） 下，只有 5% 的 Goe 可以穿透三重传输系统，其中 Fe-OTC 复合物降低了 Goe 的 Zeta 电位，从而提高了其传输能力。与单个 Fe2+ 的渗透相比，由于 OTC 对 Fe 氧化还原循环的促进作用，Fe2+ 传输增加了 13.2 %，而 Goe 和 Fe2+ 之间的电子转移效应抑制了 46.6 %。与 mg/L 水平相比，μg/L OTC 对 Fe 和 Goe 迁移的影响显著降低。OTC 主要通过与 Fe 的复杂内部氧化、弱吸附、化学吸附和羟基降解作用来消除，但这些作用在低温下减弱，而在高温下增强。这项研究更深入地了解了 Fe 和抗生素在低流区转运的复杂机制，强调了温度和化学相互作用的重要作用，尤其是在季节变化期间。