Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns

Microplastics are environmentally persistent pollutants. Transport of microplastics away from root zones by infiltrating water is potentially crucial in remediating polluted agricultural soils. However, existing knowledge suggests that microplastics are retained and dispersed within the root zone un...

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Main Authors: Xiaomei Yang, Ronglong Chen, Darrell W.S. Tang
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Agricultural Water Management
Subjects:
Online Access:http://www.sciencedirect.com/science/article/pii/S0378377425004652
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author Xiaomei Yang
Ronglong Chen
Darrell W.S. Tang
author_facet Xiaomei Yang
Ronglong Chen
Darrell W.S. Tang
author_sort Xiaomei Yang
collection DOAJ
description Microplastics are environmentally persistent pollutants. Transport of microplastics away from root zones by infiltrating water is potentially crucial in remediating polluted agricultural soils. However, existing knowledge suggests that microplastics are retained and dispersed within the root zone under typical agricultural water balances. To investigate the underlying mechanisms, we sampled two soil types and conducted experiments in both disturbed and undisturbed soil columns. Microplastics were introduced into the surface, then transported deeper under multiple irrigation-drying cycles. Microplastic concentrations in soil matrices and fracture zones were separately measured, to investigate transport behavior arising from preferential flow. For all disturbed soil columns, even after 120 cm water (before correction for porosity) was applied over seven irrigation-drying cycles, over 80 % of the microplastic mass remained within the shallowest 5 cm. Furthermore, microplastics were detected beneath 40 cm depth only after seven irrigation-drying cycles. The undisturbed columns exhibited slightly greater transport, especially through fractures, but similar overall behavior with disturbed columns. Microplastic concentrations in soil matrices and fractures were highly correlated, suggesting primarily diffusive transport, and that the strong retardation of microplastic transport was similarly dominant within the matrices and fractures. Hence, mechanically remediating microplastic polluted soils by leaching is challenging, and preventing pollution is crucial.
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publisher Elsevier
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series Agricultural Water Management
spelling doaj-art-50fb10c67dcc42b3a6f47f089c3eae9a2025-08-22T04:55:07ZengElsevierAgricultural Water Management1873-22832025-09-0131810975110.1016/j.agwat.2025.109751Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columnsXiaomei Yang0Ronglong Chen1Darrell W.S. Tang2State Key Laboratory of Soil and Water Conservation and Desertification Control, College of Soil and Water Conservation Science and Engineering, Northwest A&F University, Yangling 712100, China; Soil Physics and Land Management, Wageningen University and Research, the NetherlandsState Key Laboratory of Soil and Water Conservation and Desertification Control, College of Soil and Water Conservation Science and Engineering, Northwest A&F University, Yangling 712100, ChinaWater, Energy, and Environmental Engineering. University of Oulu, Finland; Corresponding author.Microplastics are environmentally persistent pollutants. Transport of microplastics away from root zones by infiltrating water is potentially crucial in remediating polluted agricultural soils. However, existing knowledge suggests that microplastics are retained and dispersed within the root zone under typical agricultural water balances. To investigate the underlying mechanisms, we sampled two soil types and conducted experiments in both disturbed and undisturbed soil columns. Microplastics were introduced into the surface, then transported deeper under multiple irrigation-drying cycles. Microplastic concentrations in soil matrices and fracture zones were separately measured, to investigate transport behavior arising from preferential flow. For all disturbed soil columns, even after 120 cm water (before correction for porosity) was applied over seven irrigation-drying cycles, over 80 % of the microplastic mass remained within the shallowest 5 cm. Furthermore, microplastics were detected beneath 40 cm depth only after seven irrigation-drying cycles. The undisturbed columns exhibited slightly greater transport, especially through fractures, but similar overall behavior with disturbed columns. Microplastic concentrations in soil matrices and fractures were highly correlated, suggesting primarily diffusive transport, and that the strong retardation of microplastic transport was similarly dominant within the matrices and fractures. Hence, mechanically remediating microplastic polluted soils by leaching is challenging, and preventing pollution is crucial.http://www.sciencedirect.com/science/article/pii/S0378377425004652Microplastic pollutionMicroplastic accumulationMicroplastic advection-diffusionIrrigation wet-dry cyclesSoil fracturesSoil heterogeneity
spellingShingle Xiaomei Yang
Ronglong Chen
Darrell W.S. Tang
Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
Agricultural Water Management
Microplastic pollution
Microplastic accumulation
Microplastic advection-diffusion
Irrigation wet-dry cycles
Soil fractures
Soil heterogeneity
title Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
title_full Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
title_fullStr Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
title_full_unstemmed Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
title_short Minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
title_sort minimal preferential transport of microplastics through macropores in irrigated disturbed and undisturbed soil columns
topic Microplastic pollution
Microplastic accumulation
Microplastic advection-diffusion
Irrigation wet-dry cycles
Soil fractures
Soil heterogeneity
url http://www.sciencedirect.com/science/article/pii/S0378377425004652
work_keys_str_mv AT xiaomeiyang minimalpreferentialtransportofmicroplasticsthroughmacroporesinirrigateddisturbedandundisturbedsoilcolumns
AT ronglongchen minimalpreferentialtransportofmicroplasticsthroughmacroporesinirrigateddisturbedandundisturbedsoilcolumns
AT darrellwstang minimalpreferentialtransportofmicroplasticsthroughmacroporesinirrigateddisturbedandundisturbedsoilcolumns