Fate of pharmaceuticals and personal care products like metronidazole, naproxen, and methylparaben and their effect on the physiological characteristics of two wetland plants

Abstract

Plants play a vital role in the phytoremediation process, attenuating various pollutants. However, the dynamic root uptake and fate of emerging pollutants in plants, along with their effects on plant characteristics, have received limited research attention. This study explores the potential of Chrysopogon zizanioides (Vetiver) and Colocasia esculenta (Taro) in mitigating pharmaceutical and personal care products (PPCPs) - metronidazole (MNZ), naproxen (NAP), and methylparaben (MeP), under hydroponic conditions. Both plants demonstrated similar specific uptake potentials for the target pollutants (5.23 to 5.76 mg/g of biomass dry weight), with pollutant accumulation in plants remaining very low (<10 %). Notably, a substantial fraction of pollutants (66.27 % to 78.42 %) underwent metabolism. Qualitative analysis identified five MNZ and NAP metabolites and six MeP metabolites in plant tissues. Over a 28-day PPCPs exposure, accumulation of reactive oxygen species (ROS) resulted in reduced chlorophyll content, root activity, protein, and carbohydrates, alongside increased oxidative stress levels. The study highlighted distinct accumulation patterns, with NAP (anion) primarily in roots and MeP (cation) and MNZ (neutral) predominantly in aerial parts. Phloroglucinol staining confirmed the intact endodermis (Casparian Strips) in Vetiver roots, indicating symplastic transport of PPCPs to aerial parts. Moreover, significant morphological alterations were observed in plant roots exposed to target pollutants. During recuperation, a decrease in accumulated ROS indicates partial self-recovery from oxidative damage. In conclusion, both Vetiver and Taro emerge as promising candidates for removing specified PPCPs, emphasizing the critical role of addressing emerging contaminants for sustainable development and preserving the environment and human wellbeing.