Interactive effect of urbanization and flood in modulating microplastic pollution in rivers

Area of Science:

• Environmental Science
• Ecotoxicology
• Riverine Ecology

Background:

• Freshwater ecosystems are crucial pathways for microplastic transport and accumulation.
• Understanding the combined impact of urbanization and flood events on riverine microplastic pollution is essential.

Purpose of the Study:

• To investigate the interaction between urbanization and flood episodes on river microplastic pollution.
• To assess how flood events influence microplastic concentration, size, color, and polymer composition in a river system.

Main Methods:

• Water surface sampling at two sites (upstream and downstream of an urban area) during two flood events.
• Chemical digestion for particle isolation and characterization using Attenuated Total Reflectance Infrared Spectroscopy (ATR-FTIR).
• Statistical analysis, including Principal Component Analysis (PCA), to interpret spectral data.

Main Results:

• Microplastic concentrations increased 5-8 fold during floods, primarily driven by river discharge, with a more pronounced effect downstream of the urban area.
• Flooding led to an increase in larger microplastic particles on the water surface.
• Downstream sites showed significant variations in microplastic color and polymer composition during floods.
• Higher carbonyl content in microplastics during floods suggests increased degradation.

Conclusions:

• Urbanization significantly modulates freshwater microplastic pollution dynamics during flood events.
• Changes in the physicochemical properties of microplastics during floods may alter their environmental risks.
• Further integration of microplastic degradation profiles into toxicity studies is recommended to assess potential risks to ecosystem and human health.