Wastewater treatment plant (WWTP) effluents are important sources of emerging contaminants at environmentally-relevant concentrations. In this study, water samples were collected from a river downstream of two WWTPs to identify practical tracers for tracking wastewater. The results of the study indicate elevated concentrations of Cl(-), nutrients (NH3-N and NO2(-)), the artificial sweetener acesulfame-K (ACE-K), and the pharmaceuticals carbamazepine (CBZ), caffeine (CAF), sulfamethoxazole (SMX), ibuprofen (IBU), gemfibrozil (GEM), and naproxen (NAP) in the river close to the WWTPs that decreased with distance downstream. A correlation analysis using the Spearman Rank method showed that ACE-K, CBZ, GEM, NAP, and Cl(-) were strongly correlated with each other over a 31 km stretch of the river in the study area. The strong correlations of these target compounds indicate that the artificial sweetener ACE-K and the pharmaceuticals CBZ, GEM, and NAP can potentially be used as co-tracers to track wastewater.

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Compound-specifi c standardized sampling and storage methods are not available for artifi cial sweeteners found in groundwater. This study aimed to understand: (1) the appropriate length of storage time for samples containing acesulfame (ACE), sucralose (SUC), saccharin (SAC), and cyclamate (CYC) in simulated groundwater (SGW); (2) conditions of their stability; and (3) which sampling materials are appropriate for sample collection. The evaluated storage conditions included acidifi cation, headspace, exposure to light, and refrigeration; the evaluated sampling materials included steel, stainless steel, aluminum, polyvinyl chloride, polyamide (nylon), polypropylene (PharMed BPT™) tubing, styrene-ethylenebutylene co-polymer (MasterFlex™) tubing, and polytetrafl uoroethylene (Tefl on™) tubing. All compounds evaluated were stable in storage at 4 °C for 241 d (8 months). Concentrations of artifi cial sweeteners were consistently within 60% to 120% of original concentrations, except ACE and SAC that were substantially lower under acidifi ed conditions at 25 °C after 241 d. Artifi cial sweetener concentrations remained nearly constant while in contact with all sampling materials except steel. SEM and TEM images showed oxidation of steel occurred; moreover, removal of all artifi cial sweetener compounds from aqueous solution had occurred after 289 d. These results suggest artifi cial sweetener analyses conducted within 14 d of sample collection produce optimal results; however, longer storage times may be acceptable under certain conditions. The results also suggest concentrations of artifi cial sweeteners in SGW are not affected by contact with typical well casing, sampling, and storage materials, with the exception of steel. The fi ndings from this study will improve the use of artifi cial sweeteners as tracers in environmental studies.Article impact statement : Artificial sweetener samples can be stored at 4 °C for up to 8 months, but should not be acidified when stored at 25 °C or be in contact with steel.