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Adsorption and uptake of functionalized nanoplastics (NPs) by wetland plant (Sphagnum): A unique pathway for polystyrene-NPs reduction in non-vascular plants

The Science of The Total Environment 2024 4 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Sijing Tang, Jin Qian, Bianhe Lu, Yuxuan He, Yin Liu, Yin Liu, Kailin Xu, Junwei Shen

Summary

Researchers found that Sphagnum moss intercepts nearly 90% of nanoplastics via its porous leaf microstructure and intracellular uptake pathways, with surface chemistry of particles determining accumulation sites — and at environmentally relevant concentrations below 1 µg/mL, the ecological function of the moss was largely unaffected.

Polymers
Body Systems

Wetlands are sources and sinks for nanoplastics (NPs), where adsorption and uptake by plants constitute a crucial pathway for NPs accumulation. This study found that Sphagnum exhibited a high potential (~89.75 %) to intercept NPs despite the lack of root systems and stomata. Two pathways for 100nm polystyrene NPs accumulation in Sphagnum were located: (i) Spiral interception and foliar adsorption. Efficient adsorption is credited to the micro/nano-interlocked leaf structure, which is porous, hydrophilic and rough. (ii) Intracellular enrichment through pores. Fluorescence tracking indicates pseudo-leaves (lateral > cephalic branches) as primary organs for internalization. Accumulation of differently functionalized NPs was characterized: PS-Naked-NPs (PS), PS-COOH-NPs (PC) and PS-NH-NPs (PN) were all largely retained by pathway (i), while pathway (ii) mainly uptake PN and PC. Unlike PS aggregation in transparent cells, PC enrichment in chloroplast cells and PN in intercellular spaces reduced pigment content and fluorescence intensity. Further, the effects of the accumulated NPs on the ecological functions of Sphagnum were evaluated. NPs reduce carbon flux (assimilation rate by 57.78 %, and respiration rate by 33.50%), significantly decreasing biomass (PS = 13.12 %, PC = 26.48 %, PN = 35.23 %). However, toxicity threshold was around 10 μg/mL, environmental levels (≤1 μg/mL) barely affected Sphagnum. This study advances understanding of the behavior and fate of NPs in non-vascular plants, and provides new perspectives for developing Sphagnum substrates for NPs interception.

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