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Exploring transferability of plastic-water hyacinth interaction and detection in rivers

iScience 2026
Giel W.A. Hagenbeek, Tim van Emmerik, Tianlong Jia, Pummarin Khamdahsag, Kittiphon Boonma, Riccardo Taormina, Thomas Mani, Marc Rußwurm

Summary

Floating clumps of invasive water hyacinth plants act like natural nets, trapping plastic trash in rivers—researchers found up to 78% of floating plastic in Southeast Asian rivers (Vietnam and Thailand) gets caught in these plant mats, with plastic levels 59 times higher there than in open water. This matters because it means these plant clusters could help scientists spot and remove river plastic before it reaches the ocean, where it breaks down into microplastics that can end up in seafood and drinking water.

Study Type Environmental

Rivers are major pathways for plastic pollution to oceans, with high emissions in tropical regions. Research in the Saigon River showed that invasive water hyacinths (WHs) can trap macroplastics and serve as proxies for detecting river plastic using remote sensing. We explore this phenomenon and its detection methods transferability to the Chao Phraya River. Along a 62.1 km river course, WHs trapped an average of 32% of floating plastics, reaching local maxima of 78%, comparable to 54%–82% in the Saigon. Plastic concentration in WHs was 59 times higher than in open water, increasing downstream. Object detection models transferred well for WHs and entangled plastics (Chao Phraya: mAP 50 = 68% and 54%; Saigon River: mAP 50 = 70% and 52%) but poorly for free-floating plastics (23% vs. 48%). Physical sampling found 14 times more plastics within WHs than imagery, highlighting WHs' role in trapping plastics and their potential for monitoring and targeted clean-up efforts.

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