Four aquatic landscape plants and three veterinary antibiotics were selected to construct a hydroponic test system to analyze the tolerance, removal effect and mechanism of antibiotics. The results indicated that antibiotic concentrations from 0 to 100 μg·L-1 promoted plant heights and leaf chlorophyll contents, while antibiotics at concentrations > 100 μg·L-1 had inhibitory effects. The ability of different plants to remove antibiotics was Acorus calamus L. > Ceratophyllum demersum L. > Thalia dealbata Fraser > Nuphar pumila (Timm) DC. The plants with the best removal of norfloxacin, sulfadimethoxine and chlortetracycline were Ceratophyllum demersum L., Acorus calamus L. and Acorus calamus L. after 12 d of hydroponic cultivation using 100 μg·L-1 antibiotics, with removal rates of 66.6%, 63.0% and 63.2%, respectively. The accumulation of antibiotics in different plant tissues was root > stem > leaf and the accumulation increased with incubation time. The diversity of plant root biofilm microorganisms decreased with increasing treatment concentrations of antibiotics, while the abundance of dominant genera (Aeromonas, Bacillus, Lysinibacillus, Providencia, and Staphylococcus) showed an increasing trend. The findings imply that the antibiotic uptake by plants and the dynamics of the rhizosphere microbial community combine to promote antibiotic removal.
Keywords: Antibiotic accumulation; antibiotic removal; aquatic landscape plant; root biofilm microbial community; veterinary antibiotic.
Different plants have different removal capacities for pollutants, and optimal plant selection is critical for antibiotic removal in phytoremediation and constructed wetland projects. Currently, although there are a small number of preliminary studies on the effect and mechanism of plant removal of antibiotics from wastewater, there is a lack of systematic understanding of the antibiotic removal capacity, uptake and accumulation characteristics, and possible coupling of microbial communities in the root zone of common aquatic landscape plants. In this study, common veterinary antibiotics (chlortetracycline, sulfadimethoxine, and norfloxacin) were selected as pollutants based on the use of veterinary medicines in farms, and common aquatic landscape plants (Acorus calamus L., Thalia dealbata Fraser, Ceratophyllum demersum L., and Nuphar pumila (Timm) DC.) were selected for hydroponic tests under different concentration treatments of antibiotics. We analyzed the tolerance, removal effect, uptake and accumulation characteristics of these plants to antibiotics in hydroponic solution and the evolutionary pattern of the microbial community in the root zone, in order to improve the understanding of the phytoremediation mechanism of antibiotics in aquatic environments. Meanwhile, this study searched for aquatic landscape plants with superior removal capacity for antibiotics, which was expected to provide a reference for phytoremediation and constructed wetland projects.