Enrichment of Persistent Organic Pollutants in Microplastics from Coastal Waters

Adsorption of benzophenone-3 and octocrylene UV filters on polyethylene: analysis by HPLC-MS/MS and voltammetry with screen-printed electrodes

Microplastics (MPs) are persistent pollutants that can adsorb contaminants, facilitating their accumulation in aquatic ecosystems. The presence of UV filters (UVFs) such as benzophenone-3 (BP3) and octocrylene (OC), exacerbates this issue, particularly in coastal areas. This study presents an innovative dual-method approach combining high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and differential pulse adsorptive stripping voltammetry (DPAdSV) to assess the adsorption of UVFs on polyethylene (PE), a widely found polymer in aquatic environments. Adsorption kinetics were analysed using pseudo-first-order (PFOM) and pseudo-second-order (PSOM) models, revealing a higher equilibrium sorption capacity for OC due to its stronger hydrophobic interactions with PE. A central composite design (CCD) was employed to enhance resources efficiency in experimentation and controlled experiments exposed the materials to both pure fresh water and synthetic seawater. The results indicate a higher adsorption affinity of OC on PE than BP3, attributed to its high octanol-water partition coefficient (log Kow 6.88) and stronger hydrophobic interactions. Exposure time was the most influential variable across both media, while pH and temperature had a significant effect on BP3 adsorption in synthetic seawater. Hydrophobic partitioning, aided by van der Waals forces, was identified as the dominant interaction mechanism for both UVFs, with π-π and electrostatic interactions playing minimal roles due to the nature of the polymer. The study provides new insights into how polymer-pollutant interactions vary across environmental conditions and offers a novel voltammetric alternative for in-situ UVFs monitoring.

Microplastic contamination in sediments: Analytical techniques and case-based evaluations

Microplastics (MPs) pollution in sediments has gained critical attention due to its pervasive presence and potential ecological risks. This review synthesizes the latest advancements in analytical techniques, providing a comprehensive overview of separation and identification methods tailored to complex sedimentary matrices. Density-based approaches, such as ZnCl2 or NaI solutions, and enzymatic digestions are increasingly refined to isolate MPs of varying sizes, yet discrepancies in mesh sizes, reagent concentrations, and digestion protocols continue to complicate cross-study comparisons. Meanwhile, cutting-edge spectroscopic tools-μFTIR, Raman imaging, thermal analyses-have greatly enhanced polymer identification down to the tens-of-micrometers scale. Case studies spanning urban estuaries to remote deep-sea basins underscore the pervasive nature of MPs worldwide, with fibers and fragments frequently dominating sediment samples. Factors such as polymer density, hydrodynamics, and biofouling contribute to the diverse distribution patterns, revealing that even ostensibly pristine environments are not exempt from contamination. Although the precise ecological and toxicological consequences of long-term sediment-bound MPs remain partly unclear, growing evidence points to intricate interactions with co-occurring contaminants and potential trophic transfer. To address these knowledge gaps, this review emphasizes the urgent need for methodological standardization and collaborative initiatives, particularly for emerging challenges like nanoplastic detection. By integrating robust sampling approaches, advanced analytical tools, and interdisciplinary research, scientists and policymakers can more accurately map and mitigate the impacts of sediment-associated MPs on aquatic ecosystems.