Spatiotemporal dynamics, traceability analysis, and exposure risks of antibiotic resistance genes in PM_2.5 in Handan,...

Fine particulate matter (PM_2.5) seriously affects environmental air quality and human health, and antibiotic resistance genes (ARGs) in PM_2.5 posed a great challenge to clinical medicine. The year of 2013-2017 was an important 5-year period for the implementation of Air Pollution Prevention and Control Action Plan (APPCAP) in China. Here, we took Handan, a PM_2.5 polluted city in northern China, as the research object and analyzed ARGs in PM_2.5 in winter (January) from 2013 to 2017. The results showed that the abundance of ARGs was the highest in 2013 (3.7 × 10^-2 copies/16S rRNA), and ARGs were positively correlated with air quality index (AQI) (r = 0.328, P < 0.05) and PM_2.5 concentration (r = 0.377, P = 0.020 < 0.05) in the 5-year period. The ARGs carried by PM_2.5 in four functional regions of sewage treatment plant, steel works, university, and park showed that sul1 and qepA had higher abundance in each functional region, and the total ARG abundance in sewage treatment plant (1.3 × 10^-1 copies/16S rRNA) was the highest, while lowest in park (2.0 × 10^-3 copies/16S rRNA). Potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) model were used to trace the pollutants at the sampling points, which indicated that the surrounding cities contributed more than quarter to the sampling points. Therefore, regional transportation reduces the spatial distribution difference of ARGs in PM_2.5. The exposure dose of ARGs in different functional regions illustrated that the total inhaled dose of ARGs in sewage treatment plant (1.7 × 10⁵ copies/d) was the highest, while lowest in park (3.2 × 10⁴ copies/d). This study is of great significance for assessing the distribution and sources of ARGs under the clean air initiative in China.