Cd与羧基化多壁碳纳米管复合胁迫下蚕豆幼苗Cd的富集与分布

Cd enrichment and distribution in broad bean seedlings under stress of Cdcombined with MWCNTs-COOH

纳米材料因大量开发、生产和应用不可避免地被释放到环境中,给生态环境和人体健康带来潜在的风险。因此为了探究羧基化多壁碳纳米管(MWCNTs-COOH)和重金属Cd双重胁迫对植物器官中Cd的富集、转运及细胞中Cd分布的影响,以及为MWCNTs-COOH与Cd复合污染对植物的毒性和生态风险性评价提供理论依据,本研究以蚕豆幼苗为试验材料,采用水培方式,设置MWCNTs-COOH(0mg·L^-1、1.5mg·L^-1、3.0mg·L^-1、6.0 mg·L^-1、12.0 mg·L^-1)+10.0μmol·L^-1 Cd5个处理组,用石墨炉原子吸收光谱法测定不同处理下蚕豆幼苗根茎叶及细胞中Cd的含量,分析MWCNTs-COOH复合Cd处理下蚕豆幼苗营养器官对Cd的富集、转运及细胞内分布状况。结果表明:复合胁迫下,3种营养器官Cd含量均高于对照;根茎叶对Cd的富集、Cd富集系数及器官间(根-茎、茎-叶)的转移系数均随MWCNTs-COOH浓度升高呈先升高后降低趋势,当MWCNTs-COOH浓度为6.0 mg·L^-1时,以上指标均达到最大值。同时,随着MWCNTs-COOH浓度的增大,根茎叶细胞中Cd逐渐从细胞壁向原生质体转移,加深了对细胞的毒害。综上所述,中低浓度的MWCNTs-COOH不仅可促进蚕豆根茎叶对Cd的累积及向上转运,而且也能加强细胞中Cd的转移。

Nanomaterials are inevitably released into the environment because of developed production and application,which brings potential risks to the ecological environment and human health.The aim of this study was to explore the effect of MWCNTs-COOH and heavy metals Cd double stress on Cd enrichment,transport,and distribution in plant organs,and provide a theoretical basis for evaluating phytotoxicity and ecological risk of the combined pollution of MWCNTs-COOH and Cd.In this study,broad bean seedlings were cultured as experimental material using the hydroponics method,and MWCNTs-COOH(0 mg·L^-1,1.5 mg·L^-1,3.0 mg·L^-1,6.0 mg·L^-1,12.0 mg·L^-1)and 10.0μmol·L^-1 Cd treatment groups were set.The contents of Cd in roots,stems,leaves,and cells of broad bean seedlings under the different treatments were determined by Graphite Furnace atomic absorption spectrometry;and Cd enrichment,transport in vegetative organs,and distribution in cells of broad bean were analyzed.The results showed that Cd contents in three kinds of vegetative organs under MWCNTs-COOH and Cd compound stresses were higher than those in CK.Cd enrichment in roots,stems,and leaves;Cd enrichment coefficient,and translocation coefficient between organs(root-stem and stem-leaf)all first increased and then decreased.The above indicators reached their maximum values when the concentration of MWCNTs-COOH was 6.0 mg·L^-1.At the same time,with the increase of MWCNTs-COOH concentration,Cd in cells of roots,stems,and leaves gradually transferred from cell wall to protoplast,which deepened the toxicity to cells.In conclusion,medium and low concentrations of MWCNTs-COOH not only promoted Cd accumulation and upward transport in roots,stems,and leaves,but also enhanced Cd transfer in cells.