Fate of carbamazepine and its effect on physiological characteristics of wetland plant species in the hydroponic system

Abstract

Plants play a cardinal role in removing various pollutants through the synergistic interaction with filling materials and microbes of constructed wetlands (CWs). However, the information regarding the selection of plant species to remove pharmaceutically active compounds (PhACs) is not adequate. The present study attempted to select an appropriate plant species for CWs, considering their characteristics and physiological response to PhACs. In this regard, batch hydroponics studies were carried out to assess the removal, fate, and antioxidative response of carbamazepine (CBZ) in four wetland plant species (Canna indica, Colocasia esculenta, Phragmites australis, and Chrysopogon zizanioides). The specific uptake potential of CBZ (in terms of plant dry biomass) was found to be in the order: C. indica (14.48 mg/g) >P. australis (11.71 mg/g) >C. esculenta (8.67 mg/g) >C. zizanioides (6.04 mg/g). The results showed that exposure to CBZ (0–30 days) caused an accumulation of reactive oxygen species (ROS) in the plant tissues, causing a decline in chlorophyll content, root activity, and increased oxidative stress. However, the selected plants could recover from the oxidative damages to a certain extent in the recuperation phase (31–60 days). C. indica exhibited relatively lesser ROS accumulation and oxidative damage during the experimental phase than other selected plants. The study also showed that plant biomass, transpiration rate, chlorophyll content, root exudates, and root activity influenced the removal of CBZ by various plants (r – 0.76 to 0.98, P < 0.05). The mass balance analysis indicated that a significant proportion of CBZ (49.2 to 72.7 %) underwent metabolism in the plant tissues. Apart from higher removal, lesser accumulation, and lower oxidation stress, multi-criteria decision analysis showed that C. indica is a potential plant species for the removal of CBZ.