Wastewater discharge drives ARGs spread in the coastal area: A case study in Hangzhou Bay, China

The distribution of 14 ARGs, intI1, and 16S rDNA were analysed in 4 wastewater treatment plants (WWTPs), 2 effluent receiving areas (ERAs), and Hangzhou Bay (HZB). The results showed that each integrated WWTP (IWWTP) received higher abundance of ARGs than pharmaceutical WWTPs (PWWTPs), and IWWTPs removed ARGs more efficiently than PWWTPs. The WWTP effluents greatly contributed to the ARGs pollution in the water environments of the ERAs and HZB, and the total abundance of the ARGs displayed a distance decay pattern. In coastal sediments, more ARGs were accumulated in remote sites. The correlation analysis showed that the occurrence of ARGs was more related to 16S rDNA and intI1 in the WWTPs. Three macrolides resistance genes (ermB, mphA, and vatB) had strong correlations with 16S rDNA and intI1 in all the sample groups. Our study clearly reveals the link between land WWTPs discharge and emerging pollution of ARGs in coastal environments. This study investigated the distribution of ARGs from WWTPs to natural bay, and explored the effects of wastewater discharge to the spread of ARGs in coastal environment. [Display omitted] •The abundances of 14 ARGs from WWTPs to natural bay were investigated.•WWTP effluents contributed to the ARGs pollution in the coastal environment.•The intI1 and 16S rDNA might have different impact on the detected ARGs.•Heavy metals and nutrients had strong positive correlations with the distribution of ARGs.