Microplastics in agricultural soils following sewage sludge applications: evidence from a 25-year study.

Ramage, Stuart J.F.F.; Coull, Malcolm; Cooper, Patricia; Campbell, Colin D.; Prabhu, Radhakrishna; Yates, Kyari; Dawson, Lorna A.; Devalla, Sandhya; Pagaling, Eulyn

Abstract

Sewage sludges applied to agricultural soils are sources of microplastic pollution, however, little is known about the accumulation, persistence, or degradation of these microplastics over time. This is the first study to provide long-term, high temporal resolution quantitative evidence of microplastics in agricultural soils following sewage sludge application. The abundance and degradation of microplastics was assessed in soils sampled biennially from an experimental field over a 25-year period managed under an improved grassland regime following the application of five different sewage sludges. The sludges contained different microplastic compositions reflecting the different sources of the sludges. Microplastic abundance increased by 723–1445% following sewage sludge applications (p < 0.05) and remained constant over time (22 years and possibly beyond) (p > 0.05). All sludges predominantly added white/transparent microfibres to soil. Microfilms, microfibres, and fragments were most susceptible to degradation, potentially creating micro(nano)plastics. Of note was the discoloration of coloured microfibres, which may be environmentally hazardous due to the toxicity of textile dyes in soil ecosystems. We also found that plastic composition could be used to trace its source. This evidence is useful in informing regulation on sewage sludge use and management, and in assessing the fate and impact of microplastics in soil.

Citation

RAMAGE, S.J.F.F., COULL, M., COOPER, P., CAMPBELL, C.D., PRABHU, R., YATES, K., DAWSON, L.A., DEVALLA, S. and PAGALING, E. 2025. Microplastics in agricultural soils following sewage sludge applications: evidence from a 25-year study. Chemosphere [online], 376, article number 144277. Available from: https://doi.org/10.1016/j.chemosphere.2025.144277

• Journal Article Type: Article
• Acceptance Date: Mar 1, 2025
• Online Publication Date: Mar 9, 2025
• Publication Date: May 31, 2025
• Deposit Date: Mar 6, 2025
• Publicly Available Date: Mar 10, 2025
• Journal: Chemosphere
• Print ISSN: 0045-6535
• Electronic ISSN: 1879-1298
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 376
• Article Number: 144277
• DOI: https://doi.org/10.1016/j.chemosphere.2025.144277
• Keywords: Microplastics; Soils; Sewage sludge; Biosolid; Degradation
• Public URL: https://rgu-repository.worktribe.com/output/2742135
• Additional Information: This article has been published with separate supporting information. This supporting information has been incorporated into a single file on this repository and can be found at the end of the file associated with this output.