The effect of microplastics on the depuration of hydrophobic organic contaminants in Daphnia magna: A quantitative model analysis

• Published in: The Science of the total environment Vol. 877; p. 162813
• Main Authors: Lin, Wei, Li, Yu, Xiao, Xiaoying, Fan, Fuqiang, Jiang, Jiakun, Jiang, Ruifen, Shen, Yong, Ouyang, Gangfeng
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.06.2023
• Subjects: Animals; Aquatic Organisms - metabolism; Biodynamic model; Daphnia; HOCs; Intestinal elimination; Kinetics; Microplastics - metabolism; Plastics - analysis; Polychlorinated Biphenyls - analysis; Polystyrenes - metabolism; Vector effects; Water Pollutants, Chemical - analysis; Biodynamic model; Kinetics; Vector effects; HOCs; Intestinal elimination
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.162813

Microplastics are emerging pollutants that can absorb large amounts of hydrophobic organic contaminants (HOCs). However, no biodynamic model has yet been proposed to estimate their effects on HOC depuration in aquatic organisms, where the HOC concentrations are time-varying. In this work, a microplastic-inclusive biodynamic model was developed to estimate the depuration of HOCs via ingestion of microplastics. Several key parameters of the model were redefined to determine the dynamic HOC concentrations. Through the parameterized model, the relative contributions of dermal and intestinal pathways can be distinguished. Moreover, the model was verified and the vector effect of microplastics was confirmed by studying the depuration of polychlorinated biphenyl (PCB) in Daphnia magna (D. magna) with different sizes of polystyrene (PS) microplastics. The results showed that microplastics contributed to the elimination kinetics of PCBs because of the fugacity gradient between the ingested microplastics and the biota lipids, especially for the less hydrophobic PCBs. The intestinal elimination pathway via microplastics would promote overall PCB elimination, contributing 37–41 % and 29–35 % to the total flux in the 100 nm and 2 μm polystyrene (PS) microplastic suspensions, respectively. Furthermore, the contribution of microplastic uptake to total HOC elimination increased with decreasing microplastic size in water, suggesting that microplastics may protect organisms from HOC risks. In conclusion, this work demonstrated that the proposed biodynamic model is capable of estimating the dynamic depuration of HOCs for aquatic organisms. The results can shed light on a better understanding of the vector effects of microplastics. [Display omitted] •A microplastics-inclusive biodynamic model was developed to estimate HOC depuration.•The relative contributions of dermal and intestinal pathways were distinguished.•The intestinal elimination pathway via microplastic promotes overall PCB elimination.•The contribution of microplastic to overall PCB elimination is related to the size.