Molecular Characteristics and Plastic Additives in Dissolved Organic Matter Derived from Polystyrene Microplastics

durch Yuanyuan Cao (CH)

Mittwoch 21.10.2026, 13:15 → 14:30 Europe/Berlin

5-1.213 - PAZIFIK / PACIFIC- Rechte Seite - Großer, unterteilbarer Konferenzraum (GEOMAR - Standort Ostufer / GEOMAR - East Shore)

By 2050, two-thirds of the global population will reside in urban areas, amplifying challenges from plastic waste and synthetic chemical inputs (Geyer et al., 2017). Microplastics (MPs), a pervasive urban pollutant, undergo environmental aging, releasing dissolved organic matter (DOM)
and plastic additives that disrupt urban water systems. In this study, photoaging processes of polystyrene MPs (PS-MPs) were simulated under varying cumulative irradiation (irradiation intensity × irradiation duration) and concentrations (1−5 g/l). Fluorescence spectroscopy, Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS), and liquid chromatography coupled with high-resolution mass spectrometry (LC−HRMS) were used to characterize PS-derived DOM (PS-DOM) and investigate and quantify its role in altering DOM composition and additive release, which is critical to urban biogeochemical cycles.

Cumulative irradiation significantly enhanced PS-MPs aging and PS-DOM release, especially beyond 75 kWh/m2. At 176.4 kWh/m2 (equivalent to 32.07 days of equatorial summer sunshine), PS-MPs exhibited substantial fragmentation from 55.66 ± 2.67 μm to 37.45 ± 3.21 μm with significant yellowing. The carbonyl index (CI) was obtained from the FTIR results and used to describe the degree of PS-MPs oxidation (Liu et al., 2021; Qiu et al., 2022). The CI of PS-MPs was increased significantly from 0.03 to 0.41. During irradiation, the PS-DOM leaching (7.76−39.40 mg-C/g) was positively correlated with the PS-MPs aging (r2 = 0.894, p < 0.001). EEM-PARAFAC analysis revealed a three-component model, including two humus-like components (C1 and C2) and one protein-like component (C3), with C1 dominant (78.55%−87.98%). Molecular analysis revealed PS-DOM contained 30.1%−31.8% unique components compared to natural DOM, with lower aromaticity and higher bioavailability. This process not only increases the release of DOM, but also alters its molecular composition of the environment, making it more bioavailable and potentially more reactive in urban aquatic systems. Furthermore, 37 hazardous plastic additives (0.56 μg/g − 6.74 mg/g) were identified in PS-DOM, including DEHP and DBP, which pose risks to urban aquatic ecosystems and public health. Notably, under the same cumulative irradiation, lower PS-MPs concentrations implied higher cumulative irradiation per unit PS-MPs, which exacerbated PS-MPs fragmentation and oxidation and improved PS-DOM leaching. For the molecular composition, PS-DOM has lower saturation and aromaticity and higher biological instability in lower PS-MPs systems. Additionally, higher cumulative irradiation per unit PS-MPs promoted a more brittle PS-MPs structure, facilitating the release of plastic additives. Total leached additives increased from 7.98 to 21.88 mg/g as PS-MPs concentrations decreased from 5 g/l to 1 g/l, with similar trends observed for individual additive.

Urban infrastructure, impervious surfaces, and prolonged UV exposure exacerbate MPs aging, linking plastic pollution to altered biogeochemical processes. This study quantifies how irradiation intensity and MPs concentration jointly drive DOM and additive release, underscoring risks to ecosystem health. Findings emphasize the urgent need for urban plastic waste management strategies to mitigate additive leaching and chemical transformations under prolonged UV exposure. Addressing these challenges is vital for safeguarding water quality and human health in rapidly urbanizing landscapes.

Meeting Link:

https://geomar.webex.com/geomar/j.php?MTID=m5aafe889ba4ee9d8d574eab3fbd47e34