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Chinese Journal of Applied Ecology ›› 2021, Vol. 32 ›› Issue (1): 317-325.doi: 10.13287/j.1001-9332.202101.037

• Original Articles • Previous Articles     Next Articles

Effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of Hydrilla verticillata

ZHANG Chen1, JIAN Min-fei1,2*, CHEN Yu-meng1, CHEN Qing-qing1, HE Xu-fen1, CONG Ming-yang3, YANG Wen-jing2   

  1. 1Jiangxi Provincial Key Laboratory of Protection and Utilization of Subtropical Plant Resources, College of Life Science, Jiangxi Normal University, Nanchang 330022, China;
    2Ministry of Education Key Laboratory of Poyang Lake Wetland and Watershed Research, Jiangxi Normal University, Nanchang 330022, China;
    3Center of Analysis and Testing, Jiangxi Normal University, Nanchang 330022, China
  • Received:2020-09-03 Accepted:2020-10-20 Online:2021-01-15 Published:2021-07-15
  • Contact: * E-mail: jianminfei@jxnu.edu.cn
  • Supported by:
    National Natural Science Foundation of China (31700168, 41967055).

Abstract: In order to evaluate the effects of polystyrene microplastics (PS-MPs) on the growth, physiology, and biochemical characteristics of submerged plants, we exposed a typical submerged plant, Hydrilla verticillata, to a series of concentrations (i.e. 0, 5, 10, 30, 50, 100 mg·L-1) of 3 μm polystyrene microplastics (PS-MPs) and measured parameters including height, biomass, chlorophyll content, antioxidant enzyme activity, photosynthetic fluorescence. The results showed that the height of H. Verticillata significantly decreased at the high PS-MP concentrations (50 to 100 mg·L-1), while the fresh weight significantly increased at the low PS-MP concentration (5 mg·L-1). The fresh weight of H. verticillata gradually decreased with the increasing PS-MP concentration but the dry weight did not change. The total amount of chlorophyll, chlorophyll a, and chlorophyll a/b significantly decreased with the increases of the PS-MP concentrations, while the chlorophyll b did not change. PS-MPs affected the antioxidant enzyme activities of H. verticillata. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were first increased and then decreased with the increasing PS-MP concentration. The chlorophyll fluorescence parameters (Fo, Fm, Fv/Fm) decreased with the increasing concentration of PS-MP and the 1-Qp-Lss value (reflective of the closing of PSⅡ reaction center) was increased under the stable state, probably due to the inhibited PSⅡ reaction center. The overall intensity of fluorescence imaging of H. verticillata decreased with the increasing concentration of PS-MPs. When the PS-MP concentration was lower than 10 mg·L-1, the photosynthetic activity of the leaves was normal. In contrast, when the PS-MP concentration was higher than 30 mg·L-1, it caused significant adverse effects on leaves, including weaker photosynthetic intensity and the presence of yellow or withered leaves. Our results suggested that H. verticillata could tolerate PS-MP pollution but its growth and photosynthesis would be inhibited at high concentrations (>30 mg·L-1). Our results provided basic information to better understand the eco-physiological effects of PS-MPs in the freshwater environment.

Key words: microplastics, Hydrilla verticillata, chlorophyll content, activity of antioxidant enzyme, photosynthetic fluorescence imaging