Urban stormwater discharge contributes more micropollutants to surface water in humid regions of China: Comparison with treated wastewater.

• Surface waters exhibit higher micropollutant levels in wet weather compared to dry conditions. • 143 micropollutants were detected and quantified in stormwater outlets in humid regions of China. • A rapid non-target screening approach combining Selenium for Python was developed. • Certain micropollutant loads from stormwater discharge were higher than that of treated wastewater. • Antibiotics, pharmaceuticals, and herbicides from stormwater discharge is undesirable. Micropollutants have raised increasing concern due to their adverse effect on ecosystems and human health. So far, the effects of micropollutants in urban stormwater discharge on surface water quality or ecosystem health remains unclear. In this study, target and non-target screening methods were used to quantify and identify micropollutants in urban stormwater, wastewater, and surface water in humid regions of China. Results showed that the average concentration of micropollutants in surface waters in wet weather was 1.8 times that in dry weather. The cumulative concentrations of 143 micropollutants in samples from stormwater discharge were in the range of 490–1659 ng/L, which were comparable to or exceeded those from wastewater discharge. In terms of mass load in the studying area, stormwater discharges contained 10.8 kg of micropollutants in the month, a higher level compared to 4.58 kg in treated wastewater. Furthermore, the calculated risk quotients revealed medium to high ecological risk to aquatic organisms from substances such as telmisartan, irbesartan, 1,7-dimethylxanthine, and caffeine at ng/L concentrations, which are in typical levels in urban stormwater and surface waters in wet weathers. Our study reveals that urban stormwater discharge is an important pathway for micropollutants to surface waters, and urges for increased emphasis on, and reinforcement of, urban stormwater monitoring and control measures to minimize the transport of micropollutants to receiving waterbodies. [Display omitted] [ABSTRACT FROM AUTHOR]