Urban river pollution has become a prominent environmental issue in China, imposing adverse impacts on public health and ecological stability. According to monitoring data from environmental authorities, 13.7% of monitoring sections along the main streams of China’s ten major river systems were rated as inferior Grade V by 2011, representing poor water quality and moderate to severe water contamination. This paper analyzes the major influencing factors of urban river water pollution, with systematic discussion on four typical pollution sources, and incorporates water monitoring technologies as core regulatory and remediation supports.

1. Domestic Sewage Discharge

Continuous urban expansion and population growth have driven a steady increase in domestic wastewater discharge across urban areas. The mismatch between rapidly growing sewage output and the construction progress of urban wastewater treatment facilities results in a large volume of domestic wastewater being discharged into urban rivers without full treatment. Such wastewater contains abundant organic matter, nitrogen, phosphorus and pathogenic microorganisms, which can deteriorate river water quality, disturb the balance of aquatic ecosystems, and induce potential health risks for residents. Real-time water quality monitoring and regular sampling detection can effectively reflect the water quality changes caused by domestic sewage discharge, providing basic data support for pollution control.

2. Industrial Wastewater Emissions

Industrial production activities in metallurgy, chemical manufacturing, textile and other sectors serve as important sources of urban river pollution. Industrial wastewater features complex components, containing residual heavy metals such as lead and cadmium, toxic organic substances and suspended solids. Insufficient supporting treatment equipment, inconsistent implementation of discharge standards and occasional leakage incidents may lead to the discharge of untreated or incompletely treated industrial effluent into river water bodies. These pollutants can deteriorate water quality and accumulate in river sediments, potentially causing persistent ecological impacts. The installation of water quality online monitoring instruments at industrial discharge outlets enables 24-hour uninterrupted water quality monitoring, which helps capture abnormal discharge behaviors in a timely manner and standardize industrial discharge management.

3. Agricultural Non-Point Source Pollution

Intensive agricultural cultivation and large-scale livestock breeding constitute major non-point pollution sources of urban rivers. Improper disposal of livestock manure can lead to the leaching of nitrogen and phosphorus into adjacent water bodies, which may trigger water eutrophication and algal growth. In addition, the excessive application of chemical fertilizers and pesticides in suburban farmlands allows residual pollutants to enter rivers through surface runoff during rainfall. This pollution pathway may disrupt aquatic food chain structures and affect the functional stability of water resources for ecological maintenance and human utilization. Regional water quality monitoring networks can track the temporal and spatial variation characteristics of agricultural non-point source pollution, supporting targeted pollution prevention.

4. Urban Stormwater Runoff

Urban stormwater runoff is a critical diffuse pollution source affecting urban river water quality. Rainfall scours impermeable urban surfaces including roads, building roofs and construction sites, carrying heavy metals, petroleum hydrocarbons, microplastics and other pollutants into river systems. Different from concentrated point-source pollution, stormwater pollution presents scattered distribution and random occurrence, bringing certain difficulties to centralized governance. Optimized water quality monitoring layout and dynamic monitoring mechanisms can effectively capture runoff pollution characteristics, laying a foundation for the formulation of targeted stormwater management schemes.

Mitigation Strategies

Targeted source control and systematic governance are essential to alleviate urban river pollution, with multi-sector collaborative improvement measures formulated as follows:

Industrial Sector: Strengthen environmental supervision and law enforcement, popularize advanced wastewater treatment technologies, and deploy Water Quality Online Monitoring Instruments at key discharge points to realize full-time water quality monitoring and ensure discharge behaviors comply with national environmental standards.

Domestic Sector: Expand the scale and efficiency of urban wastewater treatment infrastructure, promote the application of decentralized sewage treatment systems in new urban areas, and carry out public publicity campaigns to enhance residents’ water conservation and environmental protection awareness.

Agricultural Sector: Guide the implementation of eco-friendly planting and breeding modes, such as the application of organic fertilizers and integrated pest management technologies, and improve the supporting facilities for livestock manure centralized treatment and resource utilization to reduce agricultural pollutant runoff.

Stormwater Management: Popularize urban green infrastructure construction, including permeable pavements and rain gardens, to intercept and purify stormwater runoff, and cooperate with dynamic water quality monitoring data to optimize urban runoff pollution control systems.

In summary, urban river water pollution is a comprehensive environmental problem induced by multiple human activities including domestic life, industrial production, suburban agriculture and urban operation. The improvement of urban river water environment requires integrated cross-sector governance, with pollution source prevention, infrastructure upgrading and whole-process water quality monitoring as core measures, so as to effectively protect urban water resources and maintain ecological system stability.