摘要
微塑料(100 nm～5 mm)作为一种新型环境污染物,具有潜在的动植物和人体健康风险,其污染已成为高度关注的全球环境问题.当前已有不少关于微塑料在水生生物体内积累的报道,但对于陆地生态系统的研究则相对匮乏,高等植物对微塑料的吸收和积累更未见报道.本文基于室内培养实验报道了微塑料在生菜(Lactuca sativa)体内的吸收、传输及分布.通过激光扫描共聚焦荧光显微镜和扫描电子显微镜观察发现,聚苯乙烯微球(0.2μm)可被生菜根部大量吸收和富集,并从根部迁移到地上部,积累和分布在可被直接食用的茎叶之中.研究结果为开展土壤-植物系统中微塑料积累机制及食物链传递与健康风险研究提供了新依据.
Microplastic(MP, 100 nm-5 mm) may present an attributable risk to ecosystem and human health, and its pollution has become a global environmental concern. Despite a wealth of information on the accumulation of MPs in aquatic species,there is no information on the uptake and accumulation of MPs by higher plants. Terrestrial edible plants are directly exposed to MPs when agricultural soil was applied with organic manure, sewage sludge as fertilizer or plastic mulching. In this paper, the uptake of two sizes of polystyrene(PS) microbeads(0.2 and 1.0 μm) and then their distribution and migration in an edible plant lettuce were firstly investigated based on laboratory experiments. We used fluorescent markers to track PS microbeads in plant tissues and found fluorescence to be a sensitive and reliable detection method. Sections from untreated control lettuce showed no autofluorescence. When roots were treated with fluorescently labeled PS microbeads, the microbeads could be identified by its fluorescence. Our main study investigated the uptake of 0.2 μm beads, as few luminescence signals were observed in lettuce roots for 1.0 μm beads in our experiment. We observed that0.2 μm fluorescent microbeads were extracellularly trapped in the root cap mucilage(which is a highly hydrated polysaccharide) and a "dark green tip"(which was typical of lettuce roots exposed to label PS beads) was usually visible to the naked eye. Confocal images revealed that the PS luminescence signals were mainly located in the vascular system and on the cell walls of the cortex tissue of the roots, indicated that the beads passed through the intercellular space via the apoplastic transport system. Once inside the central cylinder, the 0.2 μm PS beads were transferred from the roots to the stems and leaves via the vascular system following the transpiration stream. We also observed that the PS beads adhered to one another and self-assembled systematically into "grape-like" and "(chain) string-like" clusters in the intercellular space of the root and stem vascular tissue of lettuce plant. In contrast to the root and stem, PS beads were dispersed in the leaf tissue. Here, for the first time we provide evidence of the adherence, uptake, accumulation, and translocation of submicrometer MPs within an edible plant. Our findings highlight the previously underappreciated human exposure pathway to MPs through the consumption of contaminated crops and emphasize the need for new management strategies to control the release of MPs waste products into the terrestrial environment. Ultimately, the potential impacts of low range sized MPs on food safety of crop plants and human health need to be urgently considered.
作者
李连祯
周倩
尹娜
涂晨
骆永明
Lianzhen Li;Qian Zhou;Na Yin;Chen Tu;Yongming Luo(Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation,Yantai Institute of Coastal Zone Research,Chinese Academy of Sciences,Yantai 264003,China;Key Laboratory of Soil Environment and Pollution Remediation,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;College of Resources and Environment,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2019年第9期928-934,共7页
Chinese Science Bulletin
基金
中国科学院前沿科学重点研究项目(QYZDJ-SSW-DQC015)
国家重点研发计划(2016YFC1402202)
国家自然科学基金(41877142)资助
关键词
微塑料
生菜
聚苯乙烯微球
吸收
积累
健康风险
microplastics
lettuce
polystyrene microbeads
uptake
accumulation
human health risk
