Phytoremediation is a low-cost and sustainable green technology that uses plants to remove organic and inorganic pollutants from aquatic environments. The aim of this study was to investigate the phytoextraction, phytoaccumulation, and phytotransformation of three fluoroquinolones (FQs) (ciprofloxacin [CIP], enrofloxacin [ENF], and levofloxacin [LVF]) by Japanese radish (Raphanus sativus var. longipinnatus) and duckweed (Lemma minor). Determination of FQs and identification of their transformation products (TPs) were performed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Inter-tissue translocation of FQs in Japanese radish tissues depended on their initial concentration in the medium. CIP (IT = 14.4) and ENF (IT = 17.0) accumulated mainly in radish roots, while LVF in leaves (IT = 230.8) at an initial concentration of 10 µg g-1. CIP (2,104 ng g-1) was detected in the highest concentration, followed by ENF (426.3 ng g-1) and LVF (273.3 ng g-1) in the tissues of both plants. FQs' bioaccumulation factors were significantly higher for duckweed (1.490-18.240) than Japanese radish (0.027-0.103). The removal of FQs from water using duckweed was mainly due to their photolysis and hydrolysis than plant sorption. In the screening, analysis detected 29 FQ TPs. The biotransformation pathways of FQs are described in detail, and the factors that influence their formation are indicated.
Keywords: Biotransformation; fluoroquinolones; phytoremediation.
This study has presented the efficiency of fluoroquinolone (FQ) residues phytoextraction from water by two plant species (water duckweed, Japanese radish). The use of two plant species allowed for a holistic study of the FQ phytoremediation process by determining the efficiency of extraction, tissue distribution, bioaccumulation tendency, and biotransformation. The research gap regarding FQ transformation products in the phytoremediation process and the factors determining their formation has been filled. This study indicated that duckweed can be used with great efficiency to purify water from FQ contamination.