*Result*: Integrated modeling to quantify transport and fate of nano-plastics in the hyporheic zone under the influence of hyporheic exchange.

Title:
Integrated modeling to quantify transport and fate of nano-plastics in the hyporheic zone under the influence of hyporheic exchange.
Authors:
Yang Z; School of Environmental Science and Engineering, Southwest Jiaotong University, Chengdu, 611756, China., Xia J; Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China., Hou J; Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China. Electronic address: hhuhjyhj@126.com., Wu J; Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China., You G; Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China., Miao L; Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes of Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, China.
Source:
Environmental pollution (Barking, Essex : 1987) [Environ Pollut] 2026 Mar 01; Vol. 392, pp. 127588. Date of Electronic Publication: 2026 Jan 04.
Publication Type:
Journal Article
Language:
English
Journal Info:
Publisher: Elsevier Applied Science Publishers Country of Publication: England NLM ID: 8804476 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1873-6424 (Electronic) Linking ISSN: 02697491 NLM ISO Abbreviation: Environ Pollut Subsets: MEDLINE
Imprint Name(s):
Original Publication: Barking, Essex, England : Elsevier Applied Science Publishers, c1987-
MeSH Terms:
Water Pollutants, Chemical*/analysis , Plastics*/analysis , Nanoparticles*/analysis , Environmental Monitoring* , Models, Chemical*, Water Movements ; Particle Size ; Models, Theoretical
Contributed Indexing:
Keywords: Hyporheic exchange; Hyporheic zone; Interception effect; Nano-plastics; Settlement action
Substance Nomenclature:
0 (Water Pollutants, Chemical)
0 (Plastics)
Entry Date(s):
Date Created: 20260106 Date Completed: 20260122 Latest Revision: 20260122
Update Code:
20260130
DOI:
10.1016/j.envpol.2025.127588
PMID:
41494584
Database:
MEDLINE

*Further Information*

*Nano-plastics (NPs) present significant environmental risks due to their small size, high reactivity, and mobility, yet their migration behavior in hyporheic zones remains poorly understood. Previous models predominantly employed one-dimensional NPs permeation in porous media that neglected critical multi-physics processes including hyporheic exchange dynamics, particle interception effects, and NPs self-settling behavior. This study pioneers an integrated modeling framework that uniquely couples overlying flow, pore water circulation, and NPs transport fields while simultaneously accounting for advection, diffusion, interception, and gravitational settling in hyporheic exchange conditions. Verified by the flume experiment, the model can accurately reflect the transport and distribution characteristics of NPs in hyporheic zone. Validated through comprehensive flume experiments, the model accurately predicts NPs distribution patterns, revealing that >90 % of NPs accumulate within the 0-8 cm sediment layer. The retention depth in the upstream face of the sand slope was slightly higher than that in the downstream face. Particle sizes and density changed NPs' migration paths in the sand slope by affecting the trapping-settling and sedimentation-suspension process, respectively. The larger particle size and higher density of NPs, the deeper NPs entered the river bed and be easier to be captured. NPs with irregular geometry (such as fibrous plastic) settle faster and migrate deeper in the sand slope. Additionally, orthogonal experimental design revealed significant interaction effects: fibrous geometry amplifies the penetration depth of large NPs compared to spherical counterparts, and irregular geometries can increase the penetration depth of low-density particles. Notably, the effect of NPs migration at low initial concentration (20 mg/L) on the riverbed characteristics such as porosity (θ) and permeability (K) can be ignored. With the increase of NPs initial concentration, the entry of NPs may cause changes in riverbed characteristics. This study is helpful to understand the migration and law of NPs during surface-groundwater exchange, and the results can provide useful information for predicting and controlling the potential risk of NPs in hyporheic zone.
(Copyright © 2026 Elsevier Ltd. All rights reserved.)*

*Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.*