赣江饮用水水源地水环境特征及潜在污染风险研究

Study on water environment characteristics and potential pollution risk of drinking water sources on Ganjiang River

为保障居民饮用水安全,掌握饮用水水源地水环境特征及其潜在污染风险尤为重要。以赣江南昌市(西湖区段)的两个饮用水水源地断面(青云水厂、朝阳水厂)及其上下游断面作为研究主体,通过调查分析各断面水环境现状、推演水源地上游污染衰减扩散过程,根据GB 3838—2022《地表水环境质量标准》研判饮用水水源地水质安全水平;通过解析水体沉积物磷释放速率与磷形态特征,评估磷内源释放对饮用水水源地的污染风险。结果表明:①赣江(西湖区段)重点断面水质基本为Ⅱ类水,青云水厂断面化学需氧量(COD)在2022年6月超Ⅱ类水标准。②饮用水水源地断面上游存在规模型排污口——前湖电排站,污染扩散模型显示对其饮用水水源地水质存在降类威胁。③赣江(西湖区段)沉积物总磷(TP)含量整体为轻中度污染状态,沉积物磷形态以铁铝结合态无机磷(Fe/Al-Pi)为主,其次是中活性有机磷(MA-Po)和钙结合态无机磷(Ca-Pi),平均占比分别为32.56%,20.72%,19.40%,平均含量分别为123.17,78.36,73.38 mg/kg。有机质(OM)含量与TP含量(R=0.873,P≤0.05)、Fe/Al-Pi含量(R=0.949,P≤0.05)显著相关。④青云水厂断面磷释放速率(v P)最大,存在较高磷释放风险。建议持续监测饮用水水源地上下游断面水质,密切关注青云水厂断面水质TP指标变化;对前湖电排站来水进行定期检测与排查溯源,避免雨污混流或废水直排入河;加强沿岸饮用水水源保护区规范化建设与管理,减少人为活动对水环境的影响。研究成果可为科学保障城市饮用水安全提供一定参考。

To ensure the safety of drinking water for residents,it is particularly important to understand the water environment characteristics and potential pollution risks of drinking water sources.Taking two drinking water source sections(Qingyun Water Plant and Chaoyang Water Plant)and their upstream and downstream sections in Nanchang City(West Lake section)of the Ganjiang River as the research subjects,the water environment status of each section was investigated and analyzed,and the pollution attenuation and diffusion process in the upstream of the water source area was deduced.According to GB 3838—2022 Surface Water Environmental Quality Standards,the water quality safety level of the drinking water source was judged.By analyzing the phosphorus release rate and phosphorus form characteristics of sediment in water bodies,we evaluated the pollution risk of endogenous phosphorus release in drinking water sources.The results showed that:①The water quality of the key sections on Ganjiang River(West Lake section)was ClassⅡwater,and the chemical oxygen demand(COD)of the section of Qingyun Water Plant exceeded the ClassⅡwater standard in June 2022.②Qianhu Electric Discharge Station,a large-scale sewage outlet upstream of the drinking water source,would downgrade the water quality according to simulation results.③The total phosphorus(TP)content in sediments of the Ganjiang River(West Lake section)was generally in a state of mild to moderate pollution.The main form of phosphorus in sediments was iron aluminum-bound inorganic phosphorus(Fe/Al-Pi),followed by moderately active organic phosphorus(MA-Po)and calcium-bound inorganic phosphorus(Ca-Pi),with average proportions of 32.56%,20.72%,and 19.4%,and average contents of 123.17,78.36,and 73.38 mg/kg,respectively.The organic matter(OM)content exhibited a significant correlation with the TP content(R=0.873,P≤0.05),and Fe/Al-Pi content(R=0.949,P≤0.05).④The section of Qingyun Water Plant had the highest phosphorus release rate(v P),indicating a high risk of phosphorus release.It is recommended to continuously monitor the water quality at upstream and downstream sections of the drinking water source,and closely monitor the TP index change of the Qingyun Water Plant section;regularly inspect and trace the water drained from the Qianhu Electric Discharge Station to avoid mixing of rainwater and sewage or the direct discharge of wastewater into the river;strengthen the standardized construction and management of riverside drinking water source protection areas,and reduce the impact of human activities on the water environment.The research results can provide certain references for scientifically ensuring the safety of urban drinking water.