The presence of estrogens has been linked to adverse ecological effects in surface waters downstream of agricultural and domestic wastewater sources. While laboratory studies suggest that these estrogens should not persist because of fast degradation rates, elevated concentrations in surface waters impacted by agricultural activities are commonly observed. Using a combination of measured data and a stream-hyporheic zone (HZ) model applied to a 100 km reach in a tile-drained catchment, we show that the HZ can increase the persistence of estrogens. Field data reveal high concentrations of sorbed estrogens in sediments and elevated in-stream concentrations during low-flow summer months, suggesting that the HZ acts as a source of estrogens when transport into the streams is minimal. Model results provide further insight into the underlying mechanisms that enable sustained estrogen concentrations in streams, with the HZ acting as a source of dissolved estrogens for 95% of the year. We show that stream water interactions with the HZ may lead to overall suppression of degradation processes and an increase in the persistence of estrogens. Results suggest that when the model considered exchange in the HZ, approximately 28%–49% of estrogen mass remained in the stream ecosystem, while all estrogen mass was degraded in a 100-km reach in the model without the HZ. The remaining mass increased with increasing estrogen sorption coefficient, and this would potentially increase the lag time for lowering estrogen concentrations in surface water bodies even when inputs have ceased. Our findings highlight the importance of including HZ dynamics in estrogen transport models.

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尽管如此，他们仍然坚持：低流区能增加雌激素在溪流中的持久性吗？

雌激素的存在与农业和生活废水源下游地表水中的不利生态影响有关。虽然实验室研究表明这些雌激素不应因降解速度快而持续存在，但通常会观察到受农业活动影响的地表水中浓度升高。使用测量数据和应用于 100 公里范围内的瓦片排水集水区的河流低流带 (HZ) 模型的组合，我们表明 HZ 可以增加雌激素的持久性。现场数据显示，在夏季低流量月份，沉积物中吸附的雌激素浓度高，河内浓度升高，这表明当运输到溪流中时，HZ 充当了雌激素的来源。模型结果提供了对使溪流中雌激素浓度持续升高的潜在机制的进一步了解，HZ 是一年中 95% 的溶解雌激素的来源。我们表明，河流水与 HZ 的相互作用可能导致降解过程的整体抑制和雌激素持久性的增加。结果表明，当模型考虑 HZ 中的交换时，大约 28%–49% 的雌激素质量保留在河流生态系统中，而在没有 HZ 的模型中，所有雌激素质量都在 100 公里范围内降解。剩余的质量随着雌激素吸附系数的增加而增加，这可能会增加降低地表水体中雌激素浓度的滞后时间，即使输入已经停止。