Health issues related to aquifer contamination with perchlorate are a growing concern in drinking water management. This study describes perchlorate transport and degradation processes from a contaminated stream toward drinking water pumping wells. Investigations are based on laboratory experiments and field measurements conducted at a well field near Bordeaux (France) in a heterogeneous carbonate aquifer interacting with a stream. Field measurements facilitated the characterization of perchlorate contamination and stream-to-aquifer flow. Experiments on columns of streambed sediments conducted in the laboratory confirmed that perchlorate had been degraded in the hyporheic zone. A one-dimensional reactive transport model was implemented to estimate Monod kinetic rates, which account for the inhibition of perchlorate degradation by nitrate. The estimated half-saturation constant for perchlorate \( \Big({k}_{1/2}^{\mathrm{Pcl}} \)) is 6.93 10⁻⁹ mol L⁻¹ and the estimated maximum specific degradation rate (\( {k}_{\mathrm{max}}^{\mathrm{Pcl}} \)) ranges between 10⁻⁵ and 4.0 10⁻³ mol L⁻¹ day⁻¹. Despite degradation in the hyporheic zone, perchlorate-contaminated stream water reaches drinking-water-production units. Such contamination highlights the effects of preferential flow paths between the stream and the pumping wells and significant hydraulic gradients caused by drawdowns. In such contexts, in spite of a good potential for degradation, riverbank filtration may not be effective for the protection of drinking water wells. Lessons from this study also reveal that contamination monitoring can be misleading: low concentrations can be reported in monitoring wells between the contaminant source and the production wells, but the latter may yet be contaminated.

与含水层被高氯酸盐污染有关的健康问题是饮用水管理中日益受到关注的问题。本研究描述了高氯酸盐从受污染的溪流向饮用水抽水井的运输和降解过程。调查基于在波尔多（法国）附近与河流相互作用的非均质碳酸盐含水层中的一个井场进行的实验室实验和现场测量。现场测量有助于表征高氯酸盐污染和河流到含水层的流动。实验室对河床沉积物柱进行的实验证实，高氯酸盐已在下流带降解。实施了一维反应传输模型来估计 Monod 动力学速率，这说明硝酸盐对高氯酸盐降解的抑制。\( \Big({k}_{1/2}^{\mathrm{Pcl}} \) ) 是 6.93 10 ^-9  mol L ^-1和估计的最大比降解率 ( \( {k}_{\ mathrm{max}}^{\mathrm{Pcl}} \) ) 范围在 10 ^-5和 4.0 10 ^-3  mol L ^-1天^{-1 之间}. 尽管在低流带发生了退化，但受高氯酸盐污染的河流水仍会到达饮用水生产单元。这种污染突出了溪流和抽水井之间的优先流动路径的影响，以及由水位下降引起的显着水力梯度。在这种情况下，尽管退化的可能性很大，但河岸过滤可能无法有效保护饮用水井。本研究的经验教训还表明，污染监测可能具有误导性：在污染源和生产井之间的监测井中可以报告低浓度，但后者可能尚未受到污染。