Adsorption of Cobalt onto Microplastics in Riverine Mesocosms: Influence of Biofilm Development
Abstract
The plastisphere critically modulates interactions among microplastics (MPs), biofilms, and trace metals under environmentally realistic conditions, governing the interfacial reactivity of plastisphere-coated microplastics. Here, we investigated cobalt (Co) adsorption onto large polypropylene (PP) primary microplastics (~4 mm) exposed for 28 days in a flow-through riverine mesocosm across a gradient of Co concentrations (0–60 µg·L−1). A multi-technique analytical approach was employed, combining inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS (LA-ICP-MS), quantitative PCR (qPCR), and scanning electron microscopy (SEM). Cobalt accumulation increased linearly with time, consistent with apparent first-order dependence on aqueous Co concentration under constant exposure, reaching 38 ± 3 mg·kg−1 after 28 days at 60 µg·L−1, with no saturation observed. The concentration-dependent Co accumulation was well described by an empirical power-law model (Q = KC0n), with the empirical coefficient K increasing linearly over time, reflecting the progressive increase in Co accumulation at a given aqueous concentration. Microbial colonization developed rapidly on MPs, with 16S and 18S rRNA gene copy numbers stabilizing after 14 days, while surface-normalized Co signals increased sharply after day 21, indicating a time-dependent modification of biofilm properties influencing Co retention. SEM confirmed complex microbial structures, including diatom-like cells. No cobalt adsorption was observed under sterile conditions, confirming the key role of biofilm presence. These findings highlight the dynamic role of the plastisphere as a chemically and biologically active interface under environmentally realistic riverine conditions, with implications for contaminant fate, bioavailability, and risk assessment in freshwater systems affected by plastic pollution.
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BibTeX
@article{gautier2026adsorption,
title = {{Adsorption of Cobalt onto Microplastics in Riverine Mesocosms: Influence of Biofilm Development}},
author = {Maud Gautier and Séverine Le Faucheur and Sandra Mounicou and Javier Jiménez-Lamana and Virginie Pellerin and Marisol Goñi-Urriza and Claire Gassie and Stéphanie Reynauld and Bruno Grassl},
journal = {Microplastics},
year = {2026},
month = sep,
doi = {10.3390/microplastics5030174},
url = {https://hal.science/hal-05757693v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Adsorption of Cobalt onto Microplastics in Riverine Mesocosms: Influence of Biofilm Development
AU - Maud Gautier
AU - Séverine Le Faucheur
AU - Sandra Mounicou
AU - Javier Jiménez-Lamana
AU - Virginie Pellerin
AU - Marisol Goñi-Urriza
AU - Claire Gassie
AU - Stéphanie Reynauld
AU - Bruno Grassl
PY - 2026
DA - 2026/09/02
JO - Microplastics
DO - 10.3390/microplastics5030174
UR - https://hal.science/hal-05757693v1
AB - The plastisphere critically modulates interactions among microplastics (MPs), biofilms, and trace metals under environmentally realistic conditions, governing the interfacial reactivity of plastisphere-coated microplastics. Here, we investigated cobalt (Co) adsorption onto large polypropylene (PP) primary microplastics (~4 mm) exposed for 28 days in a flow-through riverine mesocosm across a gradient of Co concentrations (0–60 µg·L−1). A multi-technique analytical approach was employed, combining inductively coupled plasma mass spectrometry (ICP-MS), laser ablation ICP-MS (LA-ICP-MS), quantitative PCR (qPCR), and scanning electron microscopy (SEM). Cobalt accumulation increased linearly with time, consistent with apparent first-order dependence on aqueous Co concentration under constant exposure, reaching 38 ± 3 mg·kg−1 after 28 days at 60 µg·L−1, with no saturation observed. The concentration-dependent Co accumulation was well described by an empirical power-law model (Q = KC0n), with the empirical coefficient K increasing linearly over time, reflecting the progressive increase in Co accumulation at a given aqueous concentration. Microbial colonization developed rapidly on MPs, with 16S and 18S rRNA gene copy numbers stabilizing after 14 days, while surface-normalized Co signals increased sharply after day 21, indicating a time-dependent modification of biofilm properties influencing Co retention. SEM confirmed complex microbial structures, including diatom-like cells. No cobalt adsorption was observed under sterile conditions, confirming the key role of biofilm presence. These findings highlight the dynamic role of the plastisphere as a chemically and biologically active interface under environmentally realistic riverine conditions, with implications for contaminant fate, bioavailability, and risk assessment in freshwater systems affected by plastic pollution.
SN - 2673-8929
ER -