Characterization of the Differences in Dissolved Organic Matter (DOM) Adsorbed on Five Kinds of Microplastics Using Multiple Methods

Xianshu Fu; Xiangliang Pan; Jun Chen; Mingzhou Zhang; Zihong Ye; Xiaoping Yu

doi:10.3390/molecules30071586

Molecules (Apr 2025)

Characterization of the Differences in Dissolved Organic Matter (DOM) Adsorbed on Five Kinds of Microplastics Using Multiple Methods

Xianshu Fu,
Xiangliang Pan,
Jun Chen,
Mingzhou Zhang,
Zihong Ye,
Xiaoping Yu

Affiliations

Xianshu Fu: College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
Xiangliang Pan: College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
Jun Chen: College of Environment, Zhejiang University of Technology, Hangzhou 310032, China
Mingzhou Zhang: Key Laboratory of Microbiological Metrology, Measurement & Bio-Product Quality Security, State Administration for Market Regulation, College of Life Sciences, China Jiliang University, Hangzhou 310018, China
Zihong Ye: Key Laboratory of Microbiological Metrology, Measurement & Bio-Product Quality Security, State Administration for Market Regulation, College of Life Sciences, China Jiliang University, Hangzhou 310018, China
Xiaoping Yu: Key Laboratory of Microbiological Metrology, Measurement & Bio-Product Quality Security, State Administration for Market Regulation, College of Life Sciences, China Jiliang University, Hangzhou 310018, China

DOI: https://doi.org/10.3390/molecules30071586
Journal volume & issue: Vol. 30, no. 7
p. 1586

Abstract

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Microplastics (MPs) are ubiquitous in aquatic environments, soils, and beach sediments, demonstrating a remarkable ability to adsorb dissolved organic matter (DOM). Although there are methods for extracting DOM from water, the approaches for directly extracting DOM from microplastics have not been thoroughly investigated, and the characterization of DOM adsorbed on microplastics is also insufficient. In this study, five different types of microplastic samples were collected from each of five environmental media (water and sediment), and finally 25 samples were obtained. This paper comparatively assessed the extraction efficiency of DOM from MPs with various solvents by using total organic carbon (TOC), culminating in the development of a sodium pyrophosphate-NaOH solution extraction method optimized for DOM. The morphology, material and environmental medium of microplastics were the three primary factors affecting the adsorption of DOM on microplastics, with the highest enrichment ratio of 1.4–1.8 times for extruded polyethylene microplastics (EPE-MPs) characterized by their porous structure in the flowing water environment. The molecular weight of DOM adsorbed on microplastics showed a multi-modal distribution pattern with great dissimilarities among the different environmental media. Gel permeation chromatography (GPC) indicated that the weight-average molecular weight (Mw) of DOM was 2750–4552 Da for river MPs, 2760–5402 Da for Qiantang River MPs, 1233–5228 Da for East China Sea MPs, 440–7302 Da for soil sediment MPs and 438–6178 Da for beach sediment MPs, respectively. Excitation-emission matrix-parallel factor analysis (EEM-PARAFAC) identified that tyrosine-like substances with high excitation in region IV and low excitation in region I were predominantly adsorbed on MPs, followed by tryptophan-like substances with low excitation in region II and protein-like substances in region IV, while humic- and fulvic-like substances in regions V and III, respectively, exhibited the least adsorption affinity. The findings underscored the critical need to comprehensively consider the interactions between MPs and DOM and their environmental impacts in pollution control strategies.

Published in Molecules

ISSN: 1420-3049 (Online)
Publisher: MDPI AG
Country of publisher: Switzerland
LCC subjects: Science: Chemistry: Organic chemistry
Website: http://www.mdpi.com/journal/molecules

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