Analysis and Change in Concentration of Micropollutants in Stream Affected by WWTP Effluents using Portable Composite Sampler and LC-HRMS

With the increase of manufacturing and use of chemicals, an increasing amount of chemicals enters surface water through various pathways. Their concentrations range from ng/L to mg/L, and they are recognized as micropollutants that pose potential risks to human health and aquatic ecosystems. This study quantitatively analyzed the diverse micropollutants in a stream affected by effluents from a waste-water treatment plant (WWTP) and demonstrated the changes in concentration over time. To capture temporal trends, water samples were collected using a portable composite sampler. For a comprehensive chemical analysis of the 148 species, target screening was conducted using liquid chromatography with high resolution mass spectrometer (LC-HRMS). As a result of the quantitative analysis, a total of 71 substances were detected at concentrations higher than the limit of quantification (LOQ). Pharmaceuticals accounted for the highest proportion among the detected substances. Tris (2-butoxyethyl) phosphate (tbep), which is used as an organophosphate flame retardant (OPFRs), was detected as a major pollutant at a maximum of 14,000 ng/L. Metformin, Pentaethylene glycol, cetirizine, galaxolidone, acetaminophen, heptaethylene glycol, carbamazepine-10,11-epoxide, sulfapyridine, valsartan acid, telmisartan, fluconazole, benzotriazole, olmesartan, 4-Methyl-1H-benzotriazole, sitagliptin, and perfluorohexanoic acid (PFHxA) were detected at concentrations of 1,000 ng/L or higher. As a unique temporal trend in the concentration, per-and polyfluoroalkyl substances (PFAS) and benzotriazoles exhibited the highest concentrations from 00:30 to 02:00 on 5/10 with a gradual decrease thereafter. The main factor responsible for this change in concentration was the effluent from the WWTP located upstream of the sampling point. In addition, the substance used in a nearby large-scale industrial complex is considered a significant factor.