Macroplastic Fate and Transport Modeling: Freshwaters Act as Main Reservoirs

Area of Science:

• Environmental Science
• Hydrology
• Ecotoxicology

Background:

• Macroplastic pollution in freshwater poses risks to ecosystems and human health.
• Understanding the movement and persistence of macroplastics is crucial for effective management.

Purpose of the Study:

• To model macroplastic fate and transport at a country scale.
• To assess the retention capacity of Swiss rivers and lakes for macroplastics.

Main Methods:

• Developed a country-scale modeling approach for macroplastic fate and transport.
• Parametrized the fate model using monitoring data and field experiment results.
• Applied the model to Swiss rivers and lakes, including sensitivity analysis.

Main Results:

• 98% of macroplastic emissions into freshwater remain within Switzerland.
• High variability in macroplastic retention was observed across catchments and rivers.
• Continuous retention (beaching) along riverbanks accounted for at least 70% of retained emissions.

Conclusions:

• Rivers function as significant long-term reservoirs for macroplastics.
• Beaching is a dominant retention mechanism compared to weirs or lakes.
• The study confirms the "rivers as plastic reservoirs" concept through country-level modeling.