Scientific study reveals how rivers in flood move plastics to the ocean

Portafolio Journalist 13.02.2026 16:09 Updated: 13.02.2026 16:09

Scientific study reveals how rivers in flood move plastics to the ocean

TL;DR

  • Rivers are identified as major routes for transporting plastics from continents to oceans, particularly during floods.
  • A study in Japan measured microplastic and mesoplastic concentrations during flood events in rivers with varied land uses.
  • Plastic concentrations increased by one to four orders of magnitude during high flow periods compared to low flow conditions.
  • Mesoplastics showed a more sensitive response to increased river flow than microplastics.
  • The study observed hysteresis loops, indicating higher plastic loads at the beginning of a flood event.
  • A significant percentage of the annual mesoplastic load was transported during a small fraction of the total time, highlighting the impact of extreme flood events.
  • The research provides direct, hourly observations during flood events, offering a rare quantitative dataset.