Antibiotic resistance genes in constructed wetlands: Driving indicators and risk assessment

• Published in: Journal of hazardous materials 2023-10, Vol.459, p.132314-132314, Article 132314
• Main Authors: Zhao, Zhenxiong, Zhang, Yuxuan, Liu, Ruizhi, Wang, Liping, Xu, Huitao, Meng, Qingjia, Gu, Xiu, Tang, Li
• Format: Article
• Language: English
• Subjects: Antibiotic resistance genes; Constructed wetlands; Environmental gradients; Risk assessment; Seasonal variation
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.132314

Constructed wetlands (CWs) were responsible for the in-depth purification of wastewater, providing an ideal environment for the transport, acquisition, and dissemination of antibiotic resistance genes (ARGs). A better understanding of influencing factors and risks of ARGs in CWs was deemed indispensable. In this research, the abundance of ARGs and mobile genetic elements (MGEs) was determined to be higher in summer and spring, ranging from 53.7 to 8.51 × 106 and 30.9–6.02 × 106 copies/mL, respectively. Seasonal variation significantly influenced the abundance of ARGs and MGEs, as well as the co-occurrence patterns among ARGs, MGEs and bacteria. However, the environmental gradients, from the influent (CW01) to the effluent (CW10), did not impose significant effects on the abundance of ARGs and MGEs. Furthermore, the ratios of pathogenic bacteria to ARG hosts and ARG risks index decreased by 50.4% and 88.54% along with the environmental gradients, indicating that CWs could act as barriers to the transfer of ARGs. Partial least squares-path modeling (PLSPM) revealed that temperature was the main driving factor of ARGs, followed by MGEs, stable and differential bacteria. This finding effectively and innovatively explored the driving indicators for the variations and risks of ARGs caused by spatial-temporal variations, providing new insights into the evaluation and control of ARGs in CWs. [Display omitted] •Innovative evaluation of ARGs on environmental gradients and seasonal variations.•ARGs were abundant in summer (>106 copies/mL) with significant seasonal variation.•Ratios of pathogen to ARG hosts decrease 50.4% with environmental gradient.•Temperature was main driven factor of ARGs (0.6863) and MGEs (0.5929).•CWs might act as a safety barrier to hinder the spread of pathogens and ARGs risk.