Anthropogenic Impacts on Antibiotic Resistance Genes and Microbial Communities in Groundwater of Taopu Industrial Park, Shanghai

Xinran Liu, Yawen Song, Yinping Miao, Jian Wang, Min Liu, Ye Li, Ye Huang

Urban groundwater is increasingly recognized as an emerging reservoir and transport pathway for antibiotics, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs), posing potential ecological and public-health risks. However, the distribution and transport mechanisms of antibiotics and ARGs in groundwater systems under complex anthropogenic pollution remain insufficiently understood. Here, we investigated groundwater in Shanghai’s Taopu Industrial Park, a region characterized by multiple industrial contamination sources. Antibiotic concentrations were quantified using ultra-performance liquid chromatography–tandem mass spectrometry, while metagenomic sequencing and high-throughput quantitative PCR were employed to characterize ARG diversity and abundance and microbial community composition. Integrated analyses were performed to elucidate the distribution and transport patterns of antibiotics, microorganisms, and ARGs, and to identify key environmental drivers. Co-occurrence network analysis was further applied to infer potential ARB hosts.
Twenty antibiotics were detected in groundwater at concentrations ranging from 24.1 to 1161.1 ng L-1, with sulfonamides dominating. Fluoroquinolones were more enriched in soil than groundwater, likely due to stronger sorption associated with their polar/ionic functional groups, whereas tetracyclines exhibited higher vertical mobility than sulfonamides. Antibiotic concentrations decreased exponentially with depth. Groundwater physicochemical parameters (dissolved organic carbon, salinity, dissolved oxygen, and conductivity) together with co-occurring polycyclic aromatic hydrocarbons (PAHs) were the major determinants of antibiotic distribution.
Groundwater microbial communities were bacteria-dominated and of relatively low diversity, with Proteobacteria, Bacteroidetes, Actinobacteria, and Firmicutes as the major phyla. Actinobacteria occurred at higher relative abundance than in other industrial groundwater systems, likely reflecting selective pressure from the combined presence of antibiotics and PAHs, consistent with their roles in PAH degradation, antibiotic production, and ARG hosting. Redundancy analysis indicated that contaminants—particularly antibiotics and PAHs—were the primary drivers of microbial community structure, exceeding the effects of physicochemical parameters (pH, dissolved organic carbon, and dissolved oxygen).
The composition and relative abundance of 21 ARG types were highly similar between soil and groundwater, with multidrug, macrolide, glycopeptide, tetracycline, and peptide resistance genes predominating in both media, suggesting potential ARG exchange and migration across compartments. In groundwater, contaminants (especially antibiotics and PAHs) were the dominant determinants of ARG profiles, followed by microbial community composition, while mobile genetic elements and physicochemical conditions further facilitated ARG dissemination. Network analysis identified several shared potential ARG-hosting genera in soil and groundwater, indicating that ARB-mediated vertical transport may represent an important pathway for ARG contamination in groundwater.
Overall, this study reveals the coupled occurrence, transport behavior, and environmental drivers of antibiotics, microbial communities, and ARGs in urban groundwater under anthropogenic influence. The findings highlight the need for integrated management strategies that reduce source pollutants and selective pressure to mitigate ARG dissemination in subsurface environments.