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

May 1, 2022

CRAES, Research Center for Eco-Environmental Sciences uses EasySensor DGT to publish the article as below:


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 PEMPs 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-plantsediment system and on the biogeochemical cycles of the freshwater ecosystems.

Changes in O2 micro-distributions around the roots of V. natans the were exposed to PE-MPs over the incubation periods. 2D co-distributions of O2 concentrations in the 1% PE-MPs groups (a,b), and the line chart shows all the experiment groups (c,d).
Two-dimensional co-distributions of labile P and S concentrations in the sediment-water profiles as measured by DGT probe analysis on Day 9.

Writers: Yu HW, Liu MM, Gang D. et al., 2022. Polyethylene microplastics interfere with the nutrient cycle in water-plant-sediment systems,Water Research, Volume 214, 118191, ISSN 0043-1354, https://doi.org/10.1016/j.watres.2022.118191.