Coupling suspect and non-target analytical methods for screening organic contaminants of concern in agricultural & urban impacted waters: Optimization and application.

Long-term exposure of contaminants to emerging concern (CECs) may pose risks to human health and ecosystems, even at low concentrations. Rivers impacted by both agricultural and urban activities experience distinctive environmental pressures due to receiving wastewaters that contain complex organics and their transformation products (TPs). In this study, we developed a regional database composed of 1200 CECs of high concern in Guangxi (South China). Further, we optimized a comprehensive analytical method for simultaneously screening for CECs and their TPs. The optimized screening method was applied to surface waters sampled from 10 different cross sections of a river that is impacted by both agricultural and urban activities. The best results of method optimization were achieved when the screening detection limit (SDL) ranged from 0.05 to 2 ng L ^-1 , and over 90% of the analytes had acceptable recovery rates ranging between 64.7% and 95.6% (RSD < 11%). Of the 1200 CECs contained in the regional database, 168 were detected in at least one sampling site of the studied river via suspect screening, and among them, 36 contaminants were found at all sampling sites. Also, 58 additional contaminants and 39 TPs were tentatively identified via non-target screening, among which 4 TPs were reported for the first time in the aquatic environment. Triazine herbicides and their TPs were identified at most of the sampling sites, with ametryn and atrazine posing relatively high risks in the river ecosystems. Furthermore, 31 known analytes were selected as standards in order to confirm the combined screening method; one false positive occurred in the non-target screening method. According to these results, the suspect screening strategy provides valuable confirmation for the identification of a wide range of CECs in water, while non-target screening can provide a reference for researchers and supplement the regional database, particularly in the study of TPs.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2021 Elsevier B.V. All rights reserved.)