AccScience Publishing / AJWEP / Online First / DOI: 10.36922/AJWEP025460357
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ORIGINAL RESEARCH ARTICLE

Toxicity effects of microplastics and lead(II) ion co-exposure on Chlorella: Protein- and enzyme-level responses

Ming Chen1† ,  Lianqi Huang1† ,  Chongzhe Dong2 ,  Ran Tu3 ,  Yang Yang1 ,  Bin Yan1* ,  Yan Wu1* ,  Guoxin Lan1*
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1 Three Gorges Reservoir Area Environment and Ecology of Chongqing Observation and Research Station, Chongqing Three Gorges University, Wan Zhou, Chongqing, China
2 Qingyuan Water Group Co., LTD., Yibin, Sichuan, China
3 Liangping Municipal Ecology and Environment Bureau, Liangping, Chongqing, China
†These authors contributed equally to this work.
AJWEP, 025460357 https://doi.org/10.36922/AJWEP025460357
Received: 16 November 2025 | Revised: 17 December 2025 | Accepted: 31 December 2025 | Published online: 10 February 2026
(This article belongs to the Special Issue Frontiers in Sustainable Development of Ecology and Environment)
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Microplastics (MPs) synergistically interact with heavy metal contaminants, posing substantial ecological threats to biota. Hydrodynamic regimes and water-level fluctuations within the Three Gorges Reservoir (TGR) critically influence contaminant dynamics. Nevertheless, biomolecular responses to MP and heavy metal co-exposure at protein and enzymatic levels remain inadequately characterized. This study selected polyethylene (PE), polypropylene (PP), and lead(II) ions (Pb2+) to examine the freshwater microalgae Chlorella vulgaris within the TGR. After 96 h of exposure, the half-maximal effective concentrations for PE and PP against C. vulgaris were determined to be 334 mg/L and 295.29 mg/L, respectively. PE, PP, and Pb2+ significantly reduced the accumulation of C. vulgaris biomass, deteriorated algal cell growth, and caused the algal cells to undergo membrane lipid peroxidation. Nitrate and phosphate assimilation were considerably inhibited across all treatments, with heightened suppression under co-exposure. MPs’ addition significantly increased malondialdehyde levels. MP adsorption of Pb2+ appeared to attenuate Pb2+-associated changes in nitrate reductase (NR) and alkaline phosphatase activities. This study provides a theoretical foundation for evaluating MP and heavy metal ecological risks in reservoir ecosystems.

Graphical abstract
Keywords
Three Gorges Reservoir
Combined toxicity
Polyethylene
Polypropylene
Lead ion
Enzyme response
Funding
This work was supported by the Scientific and Technological Research of Chongqing Municipal Education Commission, under the project “Research on the effect of microplastics on algal growth in a typical ablation zone” (KJQN202401234).
Conflict of interest
Chongzhe Dong is an employee of Qingyuan Water Group Co., LTD. The authors declare that this affiliation did not influence the study design, data collection, analysis, interpretation, or the decision to publish. The remaining authors declare no competing interests.
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Asian Journal of Water, Environment and Pollution, Electronic ISSN: 1875-8568 Print ISSN: 0972-9860, Published by AccScience Publishing
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