The role of coated fertilizer used in paddy fields as a source of microplastics in the marine environment

Naoya Katsumi*, Takasei Kusube, Seiya Nagao, Hiroshi Okochi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Fixed-point and multi-point field survey was conducted to determine the actual contamination of the Japanese coast by microcapsules derived from coated fertilizers. The results indicated that the amount of microcapsules increased during the irrigation season (9423–74,869 pieces/m2) and decreased in the non-irrigation season (77–1471 pieces/m2). Microcapsules accounted for 90% of all microplastics sampled during the irrigation season. The lack of correlation between the area of agricultural land in the watershed and the microcapsule density on the coast suggested that the density of microcapsules on the coast was not only dependent on the total load to the ocean, but also on topographic and meteorological conditions. More than 90% of the microcapsules collected from the shoreline were made of polyethylene. Scanning electron microscopic observation of the surface of the microcapsules revealed that portions of the microcapsules were removed as secondary microplastics in the process of migration to the ocean.

Original languageEnglish
Article number111727
JournalMarine Pollution Bulletin
Publication statusPublished - 2020 Dec


  • Coated fertilizer
  • Microcapsules
  • Microplastics
  • Paddy fields

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science
  • Pollution


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