【作者】 刘涛；

【导师】 石辉；

【作者基本信息】 西安建筑科技大学 ， 资源与环境（专业学位）， 2023， 硕士

【摘要】 微/纳米塑料作为一种新型污染物,近几年被广泛关注。尽管许多研究报道了微/纳米塑料对海洋生物的影响,但它们对陆地生态系统的潜在影响在很大程度上仍然未知。植物作为土壤生态系统中的重要组成部分,其生长不可避免地受到土壤微塑料的直接或间接影响。然而针对微/纳米塑料和植物的相互作用及其机理研究还在初级研究阶段,影响机制尚不确定。因此,本论文采用水培控制实验,研究了不同浓度(0、10、20、50 mg·L^-1)、不同粒径（0.2、0.5、1μm）的塑料颗粒对玉米种子萌发和幼苗生长的影响,通过激光共聚焦显微镜对荧光标记塑料颗粒进行追踪,研究了玉米对亚微米聚苯乙烯塑料颗粒的吸收和积累。获得主要研究结果如下:（1）聚苯乙烯塑料颗粒主要通过吸附于玉米种皮表面,造成种皮物理性堵塞,从而降低了种子萌发初期吸收水分的速度,抑制了种子活力、胚芽发育和根长。但暴露72 h后对种子水分吸收没有影响,对种子萌芽的负效应则逐渐消失,最终发芽率为83.33～100%,对玉米种子的萌发无显著影响。（2）在玉米培养期内,1 mg·L^-1浓度的聚苯乙烯塑料颗粒都对玉米生长没有显著影响,但10、20、50 mg·L^-1浓度会不同程度的抑制玉米株高、根长、地上和地下生物量生长,抑制作用随浓度增加而增加,随培养时间增加而降低。聚苯乙烯塑料颗粒浓度相同时,颗粒粒径的影响只出现在培养的前5天,后期各个粒径处理之间的差异不显著。（3）聚苯乙烯塑料颗粒可导致玉米根系的SOD、POD酶活性活性增加,在浓度和粒径之间存在显著差异。（4）对荧光标记的聚苯乙烯塑料颗粒进行追踪,证明了聚苯乙烯塑料颗粒能够进入玉米根中,并能通过根尖和次生根起始部位的内皮层细胞运输到根中柱;聚苯乙烯塑料颗粒在根中主要通过质外体途径进行运输。暴露于1μm聚苯乙烯塑料颗粒的根中柱的荧光信号强度低于暴露于0.2μm处理,1μm大小的颗粒相比小粒径的颗粒可能更难以通过质外体途径在根中运输。更多还原

【Abstract】 Micro/nano plastics,as a new type of pollutant,have received widespread attention in recent years.Although many documents have reported the impact of microplastics on marine organisms,their potential impact on terrestrial ecosystems is still unknown.As an important component of soil-vegetation ecosystems,plant growth is inevitably influenced directly or indirectly by soil microplastics.However,research on the interaction between micro/nano plastics and plants is still in its early stages,and the impact mechanism is still uncertain.Therefore,we used hydroponic control experiments to study germination and seedling growth of maize for different concentrations(0,10,20,50 mg·L^-1)and particle sizes（0.2,0.5,1μm）treatment.The absorption and accumulation of submicron polystyrene plastics particles in maize was investigated by tracking fluorescence labeled particles using a laser confocal microscope.The main research results obtained are as follows:（1）The polystyrene plastics particles mainly adsorb onto the surface of maize seed coat,forming physical blockage of the seed coat,thereby reducing the rate of water absorption during the early stage of seed germination,thereby inhibiting seed vitality,embryonic development and root length.However,there is no effect on seed water absorption after 72 hours of exposure,and the negative effect on seed germination gradually disappears.The final germination rate is 83.33～100%,and there is no effect on the germination of maize seeds between control and treatment.（2）During the maize cultivation period,the polystyrene plastic particles with concentration of 1 mg·L^-1 did not significantly affect maize growth,but concentrations of10,20,and 50 mg·L^-1 inhibited plant height,root length,aboveground and underground biomass growth.The inhibitory degree increased with increasing polystyrene plastic particles concentration and decreased with increasing cultivation time prolong.When the concentration of polystyrene plastic particles is the same,the effect of particle size only appears in the first 5 days of cultivation,and the difference between different particle size treatments in the later stage is not significant.（3）The polystyrene plastic particles can lead to an increase in the activity of SOD and POD enzymes in maize roots,with significant differences between concentration and particle size.（4）The tracing of fluorescent labeled polystyrene plastic particles has demonstrated that polystyrene plastic particles can enter maize roots,and be transported to the root stele through the endodermis cells at the root tip and the starting site of secondary roots.The plastic particles are mainly transported in the root through the extracellular pathway.The fluorescence signal intensity of the root stele exposed to size with 1μm particles is lower than that exposed to the treatment with 0.2μm szie.That particles with 1μm size may be more difficult to transport through the extracellular pathway in the root compared to particles of small size.更多还原