Abstract：
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-NH2-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.
摘要：
湿地是纳米塑料(NPs)的来源和汇，其中植物的吸附和吸收构成了NPs积累的关键途径。这项研究发现，尽管缺乏根系和气孔，泥炭藓仍具有很高的拦截NPs的潜力（〜89.75％）。位于泥炭藓中100nm聚苯乙烯NPs积累的两个途径：（i）螺旋截留和叶面吸附。高效吸附归功于微/纳米互锁的叶片结构，它是多孔的，亲水和粗糙。(ii)通过孔的细胞内富集。荧光跟踪表明假叶(侧枝>头枝)作为内化的主要器官。表征了不同官能化的NP的积累：PS-裸-NP（PS），PS-COOH-NP（PC）和PS-NH2-NP（PN）均通过途径（i）保留，而途径(ii)主要吸收PN和PC。与透明细胞中的PS聚集不同，叶绿体细胞中的PC富集和细胞间隙中的PN降低了色素含量和荧光强度。Further,评价了NPs的积累对泥炭藓生态功能的影响。NPs降低碳通量(同化率57.78%，和呼吸率33.50%)，生物量显著下降(PS=13.12%，PC=26.48%，PN=35.23%）。然而,毒性阈值约为10μg/mL，环境水平（≤1μg/mL）几乎不影响泥炭藓。这项研究促进了对NPs在非维管植物中的行为和命运的理解，并为开发泥炭藓基质进行NPs拦截提供了新的视角。
