Size-dependent vector effects of microplastics on bioaccumulation of hydrophobic organic contaminants in earthworm: A dual-dosing study

• Published in: Environment international Vol. 186; p. 108625
• Main Authors: Wang, Jie, Tao, Jianguo, Wu, Mochen, Sun, Yuanze, Su, Yu, Guo, Xuetao, Du, Xinyu, Li, Jun, Gan, Jay
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.04.2024; Elsevier
• Subjects: Animals; Bioaccumulation; Earthworm; HOCs; Hydrophobic and Hydrophilic Interactions; Isotope-labeling; Microplastics; Oligochaeta - metabolism; Soil - chemistry; Soil Pollutants - metabolism; Vector effects; Earthworm; Microplastics; Vector effects; Bioaccumulation; Isotope-labeling; HOCs
• ISSN: 0160-4120; 1873-6750
• DOI: 10.1016/j.envint.2024.108625

[Display omitted] •A dual-dosing method was developed to trace HOCs from soil and microplastics.•The bioavailability of unlabeled and isotope-labeled HOCs was compared.•Reversible sorption of labeled HOCs from MPs induced greater bioavailability.•The vector effects of smaller microplastics were greater for HOC bioaccumulation.•The dual-dosing method could directly quantify and compare the vector effects. The potential of microplastics to act as a vector for anthropogenic contaminants is of rising concern. However, directly quantitatively determining the vector effects of microplastics has been rarely studied. Here, we present a dual-dosing method that simulates the chemical bioaccumulation from soil and microplastics simultaneously, wherein unlabeled hydrophobic organic contaminants (HOCs) were spiked in the soil and their respective isotope-labeled reference compounds were spiked on the polyethylene microplastics. The comparison of the bioavailability, i.e., the freely dissolved concentration in soil porewater and bioaccumulation by earthworm, between the unlabeled and isotope-labeled HOCs was carried out. Relatively higher level of bioavailability of the isotope-labeled HOCs was observed compared to the unlabeled HOCs, which may be attributed to the irreversible desorption of HOCs from soil particles. The average relative fractions of bioaccumulated isotope-labeled HOCs in the soil treated with 1 % microplastics ranged from 6.9 % to 46.4 %, which were higher than those in the soil treated with 0.1 % microplastics. Treatments with the smallest microplastic particles were observed to have the highest relative fractions of bioaccumulated isotope-labeled HOCs, with the exception of phenanthrene, suggesting greater vector effects of smaller microplastic particles. Biodynamic model analysis indicated that the contribution of dermal uptake to the bioaccumulation of isotope-labeled HOCs was higher than that for unlabeled HOCs. This proposed method can be used as a tool to assess the prospective vector effects of microplastics in complex environmental conditions and would enhance the comprehensive understanding of the microplastic vector effects for HOC bioaccumulation.