Wavelength Sensitive Plastic Photodissolution: Elucidating Quantum Yield Trends for Solar Activation Spectra

Area of Science:

• Environmental Science
• Photochemistry
• Polymer Science

Background:

• Plastic photodissolution into dissolved organic carbon (DOC) is a significant pathway for plastic degradation in aquatic systems.
• Understanding the specific wavelengths driving this process is crucial for accurate environmental modeling.
• Current knowledge gaps limit precise prediction of plastic photodissolution rates.

Purpose of the Study:

• To investigate the impact of solar excitation wavelength on plastic photodissolution rates.
• To determine the specific wavelengths responsible for photodissolution across various plastic types.
• To improve models predicting plastic photodissolution in natural waters.

Main Methods:

• Irradiation of diverse plastic films (commercial and postconsumer) using custom-built light-emitting diode (LED) photoreactors (275-445 nm).
• Measurement of dissolved organic carbon (DOC) release rates under different wavelength exposures.
• Calculation of photodissolution quantum yields and activation spectra for transparent plastics.

Main Results:

• Plastics exhibit strong wavelength sensitivity, with highest DOC release rates observed under short-wavelength ultraviolet (UV) light.
• Solar UV light between 300-350 nm was identified as the primary driver for photodissolution across all tested plastic compositions.
• Photodissolution rates were predicted within aquatic water columns based on experimental findings.

Conclusions:

• The study pinpoints specific UV wavelengths (300-350 nm) critical for plastic photodissolution.
• Findings enhance the ability to model and predict plastic photodissolution rates in natural aquatic environments.
• This research provides essential data for understanding plastic fate and transport in the environment.