摘要
农用地土壤中微塑料的积累及分布已有报道,食用蔬菜在溶液培养下能吸收微塑料也已被发现,但微塑料能否在固相培养条件下进入禾本科作物中并在体内传递积累尚未被证实.本研究选用小麦作为模式植物,以0.2μm荧光标记聚苯乙烯微球为供试微塑料材料,采用真实河砂盆栽培养实验,结合激光共聚焦荧光显微和扫描电子显微技术,发现小麦幼苗在砂培条件下能吸收和传输0.2μm聚苯乙烯微球.小麦幼苗在含有荧光标记微球的河砂中生长21 d后,其根部维管柱和外皮层细胞壁间隙组织中呈现较强的荧光分布,表明这种亚微米级塑料微球能被小麦吸收进入根部外皮层质外体空间和维管组织.塑料微球进入根部维管柱后,可通过维管组织运输到地上部的茎部维管束和叶片的脉管组织中.研究结果为进一步认知土壤-作物系统中微塑料的传递与积累机制提供了方法学和科学依据.
Microplastics pollution is becoming a global environmental concern, and growing evidence has demonstrated the accumulation and distribution of microplastics in terrestrial ecosystems. Once entering into soil, microplastics can change the physical, chemical and biological properties of soil, and then affect the growth of plants. Currently, most attentions have focused on the toxic effects of microplastics on terrestrial plants, only very limited report showed the uptake of microplastics by higher plants under hydroponic culture conditions. The nutrient solution is useful in understanding the mechanism of microplastics uptake, however, it does not account for the importance of affecting factors in the real environment(e.g., the presence of soil organic matter) and therefore do not represent the actual uptake of microplastics in the real-world. Here, we aim to determine whether wheat plants growing in a sand matrix are able to take up 0.2 μm polystyrene(PS) microbeads and translocate these particles from roots to shoots. Wheat was chosen as a representative of cereal crops because it is one of the main staple foods worldwide. A simple and rapid approach for the imaging of fluorescently labelled PS microbeads within plant tissues by confocal laser scanning microscope(CLSM) was used to investigate the uptake, accumulation, translocation and distribution of microspheres in the wheat plant. Two different fluorescent dyes were encapsulated into the PS microbeads matrix and they were used to detect the localization of PS beads in the root and the green tissue respectively. The presence of PS microbeads in plant tissue was then verified using scanning electron microscopy(SEM). 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 wheat seedling roots after exposure in sand matrix with a concentration of 0.5 g kg-1 of PS beads for 21 d, indicated that the beads passed through the intercellular space via the apoplastic transport system. Microbeads clusters were observed in the intercellular space of epidermal tissues and the steles by SEM. 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. Here, for the first time, we provide evidence of the adherence, uptake, accumulation, and translocation of submicrometer(0.2 μm) PS within the cereal plant in real sand matrix. Our findings provide a methodology and scientific basis for study of the accumulation mechanism of microplastics in soil-crop systems and their potential risk in food chain transfer.
作者
李瑞杰
李连祯
张云超
杨杰
涂晨
周倩
李远
骆永明
Ruijie Li;Lianzhen Li;Yunchao Zhang;Jie Yang;Chen Tu;Qian Zhou;Yuan Li;Yongming Luo(Key Laboratory of Coastal 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
2020年第20期2120-2127,共8页
Chinese Science Bulletin
基金
国家自然科学基金(41877142)
中国科学院前沿科学重点研究计划(QYZDJ-SSW-DQC015)
国家重点研发计划(2016YFC1402202)资助。
关键词
小麦幼苗
聚苯乙烯微球
砂培
吸收
积累
wheat seedling
polystyrene microbeads
sand culture
uptake
accumulation
