Spectroscopic evidence for adsorption of natural organic matter on microplastics

Abstract

The interaction of microcroplastics (MP) with dissolved organic matter, especially humic substances, is of great importance in understanding the behavior of microplastics in aquatic ecosystems. Surface modification by humic substances plays an essential role in transport and interaction of MP with abiotic and biotic components. Previous studies on the interaction between MP and humic substances were largely based on a model compound, humic acid (Sigma‐Aldrich). In our work, we therefore investigated the interaction of natural organic matter (NOM) sampled from a German surface water with low‐density polyethylene particles (LDPE). High‐pressure size exclusion chromatography (HPSEC) and UV/vis absorption and fluorescence spectroscopy were used to characterize the incubation solutions after modifications due to the presence of LDPE, and Raman spectroscopy was used to characterize the incubated microplastics. While the studies of the solutions generally showed only very small effects, Raman spectroscopic studies allowed clear evidence of the binding of humic fractions to MP. The comparison of the incubation of NOM and a lignite fulvic acid which also was tested further showed that specific signatures of the humic substances used could be detected by Raman spectroscopy. This provides an elegant opportunity to conduct broader studies on this issue in the future.

The deciphering of microplastics‐derived fluorescent dissolved organic matter in urban lakes, canals, and rivers using parallel factor analysis modeling and mimic experiment

“…Among these techniques, 3D-EEM is widely utilized (Lee et al, , 2021 due to its convenient sample preparation and costeffectiveness. To characterize microplastics-derived fDOM, used two-dimensional correlation spectroscopy based on FTIR, Paul et al (2024) used high-pressure size exclusion chromatography, Dittmar and Stubbins (2013) used nuclear magnetic resonance, Abdurahman et al (2020) and Li, Ma, et al (2022) used UV-vis spectrophotometer, and Li, Xi, et al (2022) used TOC analyzer, 3D-EEM, and GC/MS.…”