Negative impacts of nanoplastics on the purification function of submerged plants in constructed wetlands: Responses of oxidative stress and metabolic processes. (1st December 2022)

• Record Type: Journal Article
• Authors: Liu, Yang; Wei, Lichao; Yu, Hongwei; Cao, Xiaofeng; Peng, Jianfeng; Liu, Huijuan; Qu, Jiuhui
• Is Part Of: Water research. Volume 227(2022)
• Publication Date: 2022-12-01
• Subjects: Polystyrene nanoplastics -- Macrophyte -- Oxidative stress -- Metabolomics -- Freshwater ecosystem; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.119339
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: PS-NPs were absorbed by insect traps, and transported upward to stems and leaves. PS-NPs activated antioxidants, like ROS metabolism enzymes and H2 O2 in leaves. Alteration of the metabolic pathway induced by PS-NPs was systematically depicted. PS-NPs diminished the growth and water purification function of plants. Abstract: Constructed wetlands (CWs) are an important barrier to prevent nanoplastics (NPs) and microplastics (MPs) from entering receiving streams. However, little is known about how the accumulation of NPs affects the growth, photosynthesis, oxidative stress responses, and metabolism of plants, especially submerged plants that are widely used in CWs for water purification. Herein, we adopted Utricularia vulgaris ( U. vulgaris ), a typical submerged macrophyte as the model plant to address the above knowledge gaps under exposure to polystyrene NPs (PS-NPs, 500 nm, 0∼10 mg·L −1 ). Results showed that PS-NPs were absorbed by insect traps and further transported to stems and leaves of U. vulgaris, which limited plant height (6.8∼72.9%), relative growth rate (7.4∼17.2%), and photosynthesis (3.7∼28.2%). U. vulgaris suffered from oxidative stresses, as evidenced by the increase in malondialdehyde, antioxidant enzymes (catalase, peroxidase, and superoxide dismutase), and H2 O2, especially under 1 and 10 mg·L −1 . Abundances of 548 metabolites were quantified, and 291 metabolites were detected with altered levels after exposure, in which 25∼34% metabolites were up-regulated, and 32∼40% metabolites were down-regulated in metabolite expression. Metabolic pathways of the tricarboxylic acid cycle and amino acid were disrupted, in which citric acid, threonine, and adenine decreased, while amino acids (like serine, phenylalanine, histidine, etc.) increased first and then decreased with increasing PS-NPs concentrations. Moreover, PS-NPs reduced the removal efficiency of total nitrogen and phosphorus from water by U. vulgaris, bringing potential risks to aquatic ecosystems. These findings have greatly enhanced our understanding of the metabolic mechanisms and interactions of aquatic macrophytes that are heavily used in CWs in response to NPs stress, as well as the impact of NPs on CWs functioning. Graphical Abstract: Image, graphical abstract