A nationwide assessment of microplastic abundance in agricultural soils: The influence of plastic crop covers within the United Kingdom

Abstract

Societal Impact Statement

Agricultural soils are substantial receptors of plastic pollution. Plastic crop covers, a facet of agriplastics, may represent an important contribution to microplastic load in agricultural soils. The authors present a nationwide study of agricultural soils in the United Kingdom, comparing microplastic load between sites where plastic crop covers are and are not used for carrot and potato production. Sites where plastic crop covers were used received a higher microplastic load compared with sites where no plastic crop cover was used. The effects of microplastic pollution are largely unknown, requiring further research to determine the impact on soil, crop and human health.

Summary

• Agricultural soils are substantial receptors of plastic pollution, with agriplastics potentially making an important contribution to the overall microplastic load to agricultural soils. The intensive use and mismanagement of plastic crop covers, particularly plastic mulch films, nets and fleeces, represent a pollution pathway.

• In this study, we have analysed the microplastic concentrations in agricultural soils in 324 samples from 108 sites across the United Kingdom, where carrots or potatoes were grown, using a combined digestion and density separation method. Microplastics were stained with Nile Red and quantified using fluorescence microscopy.

• Microplastic concentrations ranged from 1320 to 8190 particles kg ⁻¹, with a mean of 3680 ± 129.1 particles kg ⁻¹. Where no plastic crop covers were used for potato and carrot production, a mean of 2667 ± 84.1 particles kg ⁻¹ were detected. At sites where plastic crop covers were used in the past 10 years, a mean of 4689 ± 147.1 particles kg ⁻¹ were recorded.

• There was a significant difference in microplastic abundance between sites where plastic crop covers were and were not used ( p ≤ 0.001), confirming that plastic crop covers are an important source of microplastics to agricultural soils. Further studies are needed to investigate microplastic occurrence in the environment to better understand their impact on soil, crops and human health.

Abstract

Los suelos agrícolas son receptores sustanciales de la contaminación plástica. Las cubiertas de plástico para cultivos, una faceta de los agroplásticos, pueden representar una contribución importante a la carga de microplásticos en los suelos agrícolas. Los autores presentan un estudio nacional de suelos agrícolas en el Reino Unido, comparando la carga de microplásticos entre los sitios donde se usan y no se usan cubiertas plásticas para cultivos para la producción de zanahorias y papas. Los sitios donde se usaron cubiertas plásticas para cultivos recibieron una mayor carga de microplásticos en comparación con los sitios donde no se usaron cubiertas plásticas para cultivos. Los efectos de la contaminación por microplásticos se desconocen en gran medida, lo que requiere más investigación para determinar el impacto en el suelo, los cultivos y la salud humana.

Abstract

Les sols agricoles sont des récepteurs importants de la pollution plastique. Les couvertures végétales en plastique, une facette des agroplastiques, peuvent représenter une contribution importante à la charge de microplastiques dans les sols agricoles. Les auteurs présentent une étude nationale des sols agricoles au Royaume‐Uni, comparant la charge microplastique entre les sites où les couvertures de culture en plastique sont et ne sont pas utilisées pour la production de carottes et de pommes de terre. Les sites où des couvertures végétales en plastique ont été utilisées ont reçu une charge microplastique plus élevée que les sites où aucune couverture végétale en plastique n'a été utilisée. Les effets de la pollution microplastique sont largement inconnus, nécessitant des recherches supplémentaires pour déterminer l'impact sur le sol, les cultures et la santé humaine.