Integrated wide-scope and class-specific nontarget analysis reveals a broad spectrum of organic micropollutants in an urban river

Abstract

Environmental monitoring using nontarget analysis (NTA) has become a powerful tool for identifying complex mixtures of organic micropollutants in aquatic systems. Herein, we developed an integrated screening strategy that combines wide-scope NTA with class-specific NTA to comprehensively characterize micropollutant occurrence in the Chaobai River, Beijing, with a watershed that features a variety of human impacts and land cover patterns. In addition to the 293 micropollutants identified through target analysis and wide-scope NTA, class-specific NTA revealed 161 additional nontarget chemicals, including 28 per- and polyfluoroalkyl substances, 50 organophosphate esters, and 83 antibiotics and their transformation products, significantly expanding the chemical space identified by traditional wide-scope NTA. Concentrations of the 454 micropollutants spanned over five orders of magnitudes, with 27 exceeding 100 ng/L (median concentration) and 23 detected in over 90 % of samples. Spatiotemporal analysis revealed four distinct micropollutant distribution patterns, with two sample groups exhibiting significantly different profiles. The lower river, influenced by reclaimed water, showed higher concentrations and more frequent detections of wastewater-derived micropollutants, whereas the upper river and reservoirs were dominated by agriculture-related micropollutants. Key micropollutants and water quality parameters were identified as robust indicators for tracking occurrence patterns. This integrated screening strategy enables the detection of a broader spectrum of chemicals and provides deeper insights into their distribution, offering a transformative and expandable framework for future environmental monitoring and risk assessment.