<p>Plant absorption is important for the entry of many pollutants into food chains. Although terrestrial microplastics (MPs) can be absorbed by the roots<sup><CitationRef CitationID="CR1">1</CitationRef>,<CitationRef CitationID="CR2">2</CitationRef></sup>, their upward translocation is slow<sup><CitationRef CitationID="CR1">1</CitationRef></sup>. Meanwhile, atmospheric MPs are widely present<sup><CitationRef CitationID="CR3">3</CitationRef>,<CitationRef CitationID="CR4">4</CitationRef></sup>, but strong evidence on their direct absorption by plants is still lacking. Here, analyses using mass spectrometry detection show the widespread occurrence of polyethylene terephthalate (PET) and polystyrene (PS) polymers and oligomers in plant leaves, and identify that their levels increase with atmospheric concentrations and the leaf growth duration. The concentrations of PET and PS polymers can reach up to 10<sup>4</sup> ng per g dry weight in leaves at the high-pollution areas studied, such as the Dacron factory and a landfill site, and 10<sup>2</sup>–10<sup>3</sup> ng per g dry weight of PET and PS can be detected in the open-air-grown leafy vegetables. Nano-sized PET and PS particles in the leaves were visually detected by hyperspectral imaging and atomic force microscopy–infrared spectroscopy. Absorption of the proactively exposed non-labelled, fluorescently labelled or europium-labelled plastic particles by maize (<i>Zea mays</i> L.) leaves through stomatal pathways, as well as their translocation to the vascular tissue through the apoplastic pathway, and accumulation in trichomes was identified using hyperspectral imaging, confocal microscopy and laser-ablation inductively coupled plasma mass spectrometry. Our results demonstrate that the absorption and accumulation of atmospheric MPs by plant leaves occur widely in the environment, and this should not be neglected when assessing the exposure of humans and other organisms to environmental MPs.</p>

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Leaf absorption contributes to accumulation of microplastics in plants

  • Ye Li,
  • Junjie Zhang,
  • Li Xu,
  • Ruoqi Li,
  • Rui Zhang,
  • Mengxi Li,
  • Chunmei Ran,
  • Ziyu Rao,
  • Xing Wei,
  • Mingli Chen,
  • Lu Wang,
  • Zhiwanxin Li,
  • Yining Xue,
  • Chu Peng,
  • Chunguang Liu,
  • Hongwen Sun,
  • Baoshan Xing,
  • Lei Wang

摘要

Plant absorption is important for the entry of many pollutants into food chains. Although terrestrial microplastics (MPs) can be absorbed by the roots1,2, their upward translocation is slow1. Meanwhile, atmospheric MPs are widely present3,4, but strong evidence on their direct absorption by plants is still lacking. Here, analyses using mass spectrometry detection show the widespread occurrence of polyethylene terephthalate (PET) and polystyrene (PS) polymers and oligomers in plant leaves, and identify that their levels increase with atmospheric concentrations and the leaf growth duration. The concentrations of PET and PS polymers can reach up to 104 ng per g dry weight in leaves at the high-pollution areas studied, such as the Dacron factory and a landfill site, and 102–103 ng per g dry weight of PET and PS can be detected in the open-air-grown leafy vegetables. Nano-sized PET and PS particles in the leaves were visually detected by hyperspectral imaging and atomic force microscopy–infrared spectroscopy. Absorption of the proactively exposed non-labelled, fluorescently labelled or europium-labelled plastic particles by maize (Zea mays L.) leaves through stomatal pathways, as well as their translocation to the vascular tissue through the apoplastic pathway, and accumulation in trichomes was identified using hyperspectral imaging, confocal microscopy and laser-ablation inductively coupled plasma mass spectrometry. Our results demonstrate that the absorption and accumulation of atmospheric MPs by plant leaves occur widely in the environment, and this should not be neglected when assessing the exposure of humans and other organisms to environmental MPs.