Wang Chao, Ye Qiu, Jia Bo-Yang, He Wen-Zhan, Dang Chao-Jun, Huang Yi, Du Lang
Post-Doctoral Scientific Research Workstation, China Three Gorges Corporation, Beijing 100038, China.
Yangtze Ecology and Environment Co., Ltd., Wuhan 430062, China.
Huan Jing Ke Xue. 2022 Mar 8;43(3):1346-1355. doi: 10.13227/j.hjkx.202106209.
Surface water pollution seriously restricts the development of the city and results in the citizens yearning for a better life. Mountainous cities have their own characteristics in surface water environment and pollution compared with those of plain cities due to their unique topography. In August and October 2019, surface water and sediments were collected in a typical river (Qingshuixi River) in the main urban area of Chongqing. These samples were analyzed for nutrients such as carbon, nitrogen, and phosphorus as well as other basic physicochemical indicators. The results showed that the surface water of the Qingshuixi River was inferior to Category V at present, and it was also at a serious pollution level according to the comprehensive pollution index evaluation system. Among all the water quality indices, NH and TP showed the most serious pollution. The tributaries of the Qingshuixi River exhibited higher surface water quality than that of the main stream, and the water quality during the rainfall season was better than that during the non-rainy season. Pollution sources, tailwater/tributary inflow, and river self-purification capacity determined the spatial distribution of nutrients in the surface water of the mainstream of the Qingshuixi River. Point sources such as the direct discharge of source sewage and pollution overflow in the middle and lower reaches were the most important sources of surface water pollution in the mainstream of the Qingshuixi River. Non-point source pollution had a limited impact on water quality. The "sink" or "source" role transformation of river sediments would occur under different water volume conditions in the river, reflecting the complexity of endogenous pollution. Surface water quality of the main stream showed a gradual improvement tendency along the downstream due to the dilution of the tail water/tributary inflow and the increased self-purification capability of the surface water in the mountainous rivers due to the increased DO content. To summarize, this study suggests that the water environment of the Qingshuixi River should be improved in comprehensive ways, which might be reducing the input of point source pollution by the deployment of the municipal pipe network in key areas, upgrading the sewage treatment plants to decrease pollutant concentrations or fluxes or channel dredging at the reaches with low DO content, etc.
地表水污染严重制约城市发展，致使市民对美好生活充满向往。山地城市因其独特地形，与平原城市相比，地表水环境及污染具有自身特点。2019年8月和10月，在重庆主城区一条典型河流（清水溪）采集地表水和沉积物样本。对这些样本进行碳、氮、磷等营养物质以及其他基本理化指标分析。结果表明，目前清水溪地表水水质劣于Ⅴ类，依据综合污染指数评价体系也处于重度污染水平。在所有水质指标中，氨氮和总磷污染最为严重。清水溪支流地表水水质优于干流，雨季水质优于非雨季。污染源、尾水/支流汇入以及河流自净能力决定了清水溪干流地表水营养物质的空间分布。中下游源污水直排和污染溢流等点源是清水溪干流地表水最重要的污染来源。非点源污染对水质影响有限。河流沉积物在不同水量条件下会发生“汇”或“源”作用的转变，反映了内源污染的复杂性。干流地表水水质沿下游方向因尾水/支流汇入的稀释作用以及山区河流中溶解氧含量增加使地表水自净能力增强而呈现逐渐改善的趋势。总之，本研究表明应综合改善清水溪的水环境，可通过在重点区域铺设市政管网减少点源污染输入、升级污水处理厂以降低污染物浓度或通量，或者对溶解氧含量低的河段进行河道清淤等方式来实现。
