Characteristics and removal of antibiotics and antibiotic resistance genes in a constructed wetland from a drinking water source in the Yangtze River Delta

Abstract

Safe drinking water is crucial to public health. However, approximately one-third of the world's population lacks access to clean drinking water. The presence of antibiotics and antibiotic resistance genes (ARGs) in drinking water sources has become a severe problem worldwide due to its potential threat to human health. We monitored the occurrence and variations of 23 antibiotics and 9 ARGs in different treatment processes in a constructed wetland serving as drinking water source in the Yangtze River Delta, China. The studied wetland is consisted of four treatment processes: pretreatment area, pump station lifting, root-channel ecological purification area and deep purification area. Except for sulfapyridine and roxithromycin, 21 antibiotics were detected at concentrations ranging from 0.15 to 59.52 ng/L. The concentration of macrolides was the highest in this wetland, especially tylosin (42.86–59.52 ng/L). TetG, tetX and sul2 were the dominant ARGs in both water (2.41 × 10−4-1.87 × 10−2) and sediment (6.65 × 10−5-4.92 × 10−3). In addition, a strong correlation between ARGs in water and ARGs in sediment (Pearson, R2 > 0.9, p < 0.05) indicated an exchange between the two phases. Moreover, the significantly positive correlation of ARGs between the inlet and outlet of each subsystem illustrated that upstream pollution was the primary source for downstream processes. In general, the wetland system could efficiently eliminate antibiotics (9.0–53.8%) and ARGs (14.5–94.1%), with the deep purification area having the highest removal efficiency. Overall, our results provide important insights into the occurrence, abundance and removal of antibiotics and ARGs in the constructed wetland serving as drinking water sources.