Emerging contaminants in the Yiwu River adjacent to China's leading international trade hub: Occurrence, ecological risk assessment and influencing factors

Urbanization, characterized by high population density and industrial diversity, accelerates the release of emerging contaminants (ECs) into aquatic environments. However, the impacts of urbanization on ECs occurrence and prevalence remain poorly understood. This study used the Yiwu River, the Yiwu city's main watercourse, as a model to evaluate impacts of urbanization on ECs distribution. 40 ECs were detected, classified into four major categories: environmental estrogens (EEs), antibiotics (ABs), organophosphate pesticides (OPPs), and phthalates (PAEs). Among them, 19 compounds exhibited detection frequencies greater than 50 %. The predominant categories were EEs and PAEs with drastically high concentrations and raising high ecological risk. The dominant EC components in mainstream mirrored those in the tributaries. However, tributaries exhibited significantly higher concentrations of both conventional water quality parameters and ECs, resulting in greater ecological risks. Spatially, EC concentrations in both mainstream and tributaries followed the trend: midstream > upstream > downstream, with the midstream region being closest to the urban center of Yiwu City. The higher ratio of artificial surfaces in the midstream (56.9 %) with a lower ratio of green covered area (only 15 %) may further deteriorate the water quality. PAEs were strongly associated with the assembly of chemical fiber-textile-dyeing industries. Finally, the alleviating solutions were proposed. The findings provide valuable insights for policymakers concerned with protecting scarce urban water resources, and offer a useful reference for researchers studying urbanization impacts on emerging contaminants. • Σ PAEs exhibited the highest concentrations among four ECs categories. • Tributaries exhibited a worse water quality compared to the mainstream. • The EEs exhibited the highest ecological risks. • Midstream leaned to the center of urban showed a severe ECs pollutant. • The alleviating strategies were proposed.