Microplastics profile in constructed wetlands: Distribution, retention and implications.

Area of Science:

• Environmental Science
• Ecotoxicology
• Water Treatment Engineering

Background:

• Microplastics (MPs) are significant aquatic pollutants originating from wastewater and stormwater.
• Constructed wetlands (CWs) are widely used for treating these water sources, but their role in MP removal is understudied.

Purpose of the Study:

• To investigate the abundance, distribution, and characteristics of MPs in water and sediment of CWs treating stormwater and wastewater.
• To assess the influence of influent source and sediment properties on MP accumulation.

Main Methods:

• Sampling and analysis of microplastic abundance and distribution in water and sediment from five CWs.
• Characterization of MP polymer types and sizes.
• Correlation analysis with environmental factors like sediment grain size.

Main Results:

• CWs significantly reduced MP concentrations in treated water compared to influent.
• MP abundance was higher in sediment than in water, indicating CWs act as MP sinks.
• Sediment grain size influenced MP distribution, with siltier sediments retaining more MPs.
• Polyethylene terephthalate (PET) fibers dominated water samples, while polyethylene (PE) and polypropylene (PP) fragments were prevalent in sediments.
• A significant proportion of sediment MPs were <300 μm, raising ecotoxicological concerns.

Conclusions:

• Constructed wetlands are effective in retaining microplastics from both wastewater and stormwater.
• CWs function as long-term sinks for microplastics, particularly in sediment.
• The accumulation of small microplastics in CW sediments poses potential risks to wetland ecosystems and biota.