Source-sink dynamics of WADA-prohibited compounds in coastal urban aquatic environments: From WWTP to bay

Urban aquatic continuums drain emerging organic micropollutants, including WADA-prohibited compounds, which may pose risks to resident health and potentially affect athletes' careers. In this study, 36 WADA-prohibited compounds were selected and quantified along an urban aquatic continuum in Shenzhen, China, spanning WWTP influent and effluent, river inlets (surface water), and ultimately Shenzhen Bay (surface sediment), with caffeine (CAF) and nicotine (NCT) included as reference stimulants. Four β-blockers (bisoprolol, metoprolol, propranolol, and sotalol), cocaine, and furosemide were quantified throughout the continuum, alongside CAF and NCT. During a week-long AM/PM sampling campaign, total loadings of the 24 quantified WADA-prohibited compounds (633 - 2326 ng L^-1, median: 955 ng L^-1) were approximately one-tenth of those of CAF and NCT in WWTP influent. Removal rates in the WWTP varied widely among the quantified compounds, ranging from negligible to 100%. Within the urban river (Dasha River), attenuation evaluated by comparing compound loadings in WWTP effluent (18 compounds at 143 - 577 ng L^-1, median: 302 ng L^-1) with those in surface water at the bay inlet (21 compounds at 167 - 512 ng L^-1, median: 315 ng L^-1) indicated slight increases in both number and concentrations of the quantified compounds, suggesting additional inputs beyond WWTP effluents. A similar pattern was observed for CAF and NCT. As a sink, surface sediment in the bay retained only 10 WADA-prohibited compounds across 4 seasonal sampling events, including fentanyl and betaxolol, which were below quantification limits in water samples, likely due to particulate-bound transport and sedimentation. Gender differences on consumption patterns might also influence environmental loadings of WADA-prohibited compounds, in contrast to CAF (with comparable coffee consumption between male and female populations) and NCT (with male-biased smoking prevalence) in the region. This catchment-based study provides a comprehensive understanding of the environmental behaviors of the WADA-prohibited compounds within an urban aquatic system.