Latent Polyester Nanoplastics in Water Environments

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Polyester fibers, including polyethylene terephthalate (PET), are widely used, leading to the continuous release of PET nanoparticles (PET-NPs) into aquatic environments.
• Previous studies reported low concentrations of PET-NPs (tens to hundreds of ng/L), potentially underestimating their prevalence due to aggregation.

Purpose of the Study:

• To develop and apply a novel method for quantifying both dispersed and aggregated PET-NPs in natural water bodies.
• To assess the distribution and concentration of PET-NPs in freshwater and saltwater environments.
• To investigate factors influencing PET-NP aggregation in aquatic systems.

Main Methods:

• A dialysis-ultrasonication-filtration method was coupled with mass spectrometry for precise quantification.
• Water samples from Chinese freshwater rivers and lakes, as well as seawater, were analyzed.
• Factors such as ionic strength and dissolved organic matter were examined for their effect on PET-NP aggregation.

Main Results:

• Dispersed PET-NPs averaged 2.23 μg/L in Chinese freshwater rivers and lakes, significantly higher than previously reported.
• Total PET-NP concentrations were higher in freshwater (average 7.02 μg/L) than in seawater (average 1.71 μg/L).
• PET-NPs aggregate more readily in seawater, influenced by Na+ and Ca2+ ions, while dissolved organic matter in freshwater inhibits aggregation.

Conclusions:

• The developed method reveals a substantial presence of PET-NPs in aquatic environments, particularly in freshwater, largely due to aggregated forms.
• PET-NP aggregation is influenced by water chemistry, with implications for their environmental fate and transport.
• Latent PET-NPs in freshwater represent a significant, under-quantified source of nanoplastic pollution.