Characterizing Atmospheric Oxidation and Cloud Condensation Nuclei Activity of Polystyrene Nanoplastic Particles

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Nanotechnology

Background:

• Nanoplastic particles (NPPs) are widespread anthropogenic pollutants.
• Understanding the atmospheric behavior of NPPs is crucial for assessing their environmental and climate impacts.

Purpose of the Study:

• To quantify the heterogeneous reaction rate and atmospheric lifetime of polystyrene (PS) nanoplastic particles (NPPs).
• To investigate the impact of atmospheric photooxidation on the hygroscopicity of NPPs.

Main Methods:

• Polystyrene NPPs were exposed to hydroxyl radicals (·OH) in a Potential Aerosol Mass (PAM) oxidation flow reactor.
• Particle mass concentration decay was monitored using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS).
• Hygroscopicity was measured using a cloud condensation nuclei counter (CCNC).

Main Results:

• The pseudo-first-order rate constant for PS particles reacting with ·OH was determined to be (3.2 ± 0.7) × 10^-13 cm³ molecule^-1 s^-1.
• The atmospheric half-lifetime of PS NPPs ranges from hours to approximately 80 days, depending on particle size and ·OH concentration.
• The hygroscopicity of 100 nm PS NPPs doubled after 27 days of photooxidation.

Conclusions:

• This study provides the first quantified atmospheric reaction rate and lifetime for PS NPPs.
• Atmospheric photooxidation significantly alters the hygroscopic properties of NPPs, potentially affecting their cloud-forming potential.
• Further research is needed to fully understand the environmental fate and climate implications of atmospheric NPPs.