Polyethylene microplastics interfere with the nutrient cycle in water-plant-sediment systems

Hongwei Yu; Miaomiao Liu; Diga Gang; Jianfeng Peng; Chengzhi Hu; Jiuhui Qu

doi:10.1016/j.watres.2022.118191

Polyethylene microplastics interfere with the nutrient cycle in water-plant-sediment systems

Water Res. 2022 May 1:214:118191. doi: 10.1016/j.watres.2022.118191. Epub 2022 Feb 14.

Authors

Hongwei Yu¹, Miaomiao Liu², Diga Gang³, Jianfeng Peng⁴, Chengzhi Hu⁵, Jiuhui Qu¹

Affiliations

¹ State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² School of Chemical & Environmental Engineering, China University of Mining & Technology-Beijing, Beijing 100083, China.
³ State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
⁴ Center for Water and Ecology, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
⁵ State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: czhu@rcees.ac.cn.

PMID: 35219185
DOI: 10.1016/j.watres.2022.118191

Abstract

Increasing microplastic (MP) pollution and its effects on aquatic systems have become a global issue; however, the impact of MPs on biogeochemical cycles is poorly understood. A simulation study was performed to analyse the influence of polyethylene (PE) microplastics on the morphological, physiological, and stoichiometric (C, N, P) characteristics of submerged plants, and to investigate their effects on the nutrient cycle and microbial community in freshwater sediment. The results showed that PE-MPs treatments significantly decreased leaf nitrogen and carbon contents. Exposure to 1% PE-MPs suppressed the plant height, total biomass, root activity, and relative growth rate of Vallisneria natans. Decrease in dissolved oxygen (DO) concentrations (19.93-40.26%) were observed in the 1% PE-MPs treatment group compared to that in the control between 1 and 6 days. The activities of enzymes (ammonia monooxygenase and nitrate reductase) related to the nitrogen cycle were significantly altered by the addition of PE-MPs. We found that PE-MPs acted as obstacle disruptors, resulting in a reduction in the release of nitrogen and phosphorus from the sediment to the overlying water. This is because PE-MPs significantly alter the composition and metabolic properties of the microbial communities in sediments, the plant growth, and the nutrient cycle. These findings helped evaluate the impacts of PE-MPs on the water-plant-sediment system and on the biogeochemical cycles of the freshwater ecosystems.

Keywords: Biogeochemistry; Ecosystems; Metabolism; Plant growth; Sediment.