Brooks are significant ecological sources and migration channels of material flow as well as energy flow in urban–rural fringes. Despite their significance, the absence of monitoring data poses challenges in assessing brook pollution risk. Taking Muli Brook as an example, a spatiotemporal variability of water quality was revealed through sample collection and water chemistry analysis. We reveal spatiotemporal variability of pollution and then developed an Exposure Index (EPI), verifying its substitution effect in assessing brook pollution risk. Our findings demonstrate a downward trend in pollution from 2020 to 2022, with exceptions in dissolved oxygen (DO) and pH. Notably, more severe pollution is observed during spring and summer, influenced by seasonal production activities and extreme weather events. Despite the diminishing disparity near urban areas, the cumulative influence of upstream pollutants outweighs that of surrounding human activities. Stronger associations between pollution risks and water area EPI were observed, compared to those of construction land and farm land. In conclusion, EPI emerges as a valuable tool for assessing brook pollution risks in urban–rural fringes, offering precise insights into brook habitat characteristics, especially in the absence of consistent monitoring data.

中文翻译：

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暴露指数替代效应评估城乡结合部溪流污染风险的证据

溪流是城乡结合部重要的生态源地和物质流、能量流的迁移通道。尽管监测数据很重要，但缺乏监测数据给评估溪流污染风险带来了挑战。以木里溪为例，通过样品采集和水化学分析揭示了水质的时空变化。我们揭示了污染的时空变化，然后制定了暴露指数（EPI），验证了其在评估溪流污染风险中的替代效应。我们的研究结果表明，从 2020 年到 2022 年，污染呈下降趋势，但溶解氧 (DO) 和 pH 值除外。值得注意的是，受季节性生产活动和极端天气事件的影响，春夏季节污染更为严重。尽管城市地区附近的差距正在缩小，但上游污染物的累积影响超过了周围人类活动的影响。与建设用地和农用地相比，污染风险与水域环境绩效指数之间的关联性更强。总之，EPI 成为评估城乡边缘溪流污染风险的宝贵工具，可以准确了解溪流栖息地特征，特别是在缺乏一致监测数据的情况下。