The release of plastics into the environment is an increasing global threat because of their eventual fragmentation into microplastics (MPs), which are now recognized as a potential global threat to human health and ecological systems. In our preliminary study, we exposed the solutions of MPs of polyethylene terephthalate (PET) and dissolved organic matter (DOM) to simulated sunlight for about 124 hours both separately and jointly. The samples (solid and solution) from these treatments were analyzed with a range of spectrometric and surface characterizations techniques. The results suggest that the co-presence of DOM and MPs mutually affect the transformation of each other even in the dark. Light irradiation further complicates the interactions of MPs and DOMs by inducing reactive species (RS).For example, changes in carbonyl vibration band of the MPs were noticed upon irradiation and such change was weakened by DOMs, likely due to the shading effect of DOM surrounding or adsorption onto MPs. Under light irradiation, the high-resolution mass spectra of the solution also varied compared to the solutions contained only either MPs or DOM at the same conditions.  In the presentation, changes in both MPs and DOM and possible mechanisms of interactions will be discussed by examining the possible reactive species such as environmental persistence free radicals (EPFRs) and reactive oxygen species (ROS).

Light-induced changes in microplastics and dissolved organic matter in their co-existence

ACS Fall 2021

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