IPMA, Instituto Português Do Mar e da Atmosfera, Rua Dr. Alfredo Magalhães Ramalho, 6, 1495-006, Lisboa, Portugal; MARE-FCUL, Centro de Ciências Do Mar e Do Ambiente, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal.
CERENA, Centro de Recursos Naturais e Ambiente, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisboa, Portugal.
Chemosphere. 2021 Mar;266:128973. doi: 10.1016/j.chemosphere.2020.128973. Epub 2020 Nov 18.
Halimione portulacoides plants were exposed to dissolved cerium (Ce) in a hydroponic medium for five days. Ce accumulation in plants followed the metal's increase in the medium although with a very low translocation factor (TF < 0.01) between roots and shoots. Ce median concentrations in roots were 586, 988 and 1103 μg/g (dry wt.), while in shoots the median values reached 1.9, 3.5 and 10.0 μg/g (dry wt.), for plants exposed to 300, 600 and 1200 μg/L of Ce, respectively. No significant differences occurred in the length of roots and shoots among treatment groups, albeit plants exposed to the highest Ce concentration showed a clear loss of turgor pressure on the fifth day. An increase of hydrogen peroxide and malondialdehyde levels were observed in the plant shoots at 1200 μg/L of Ce. The highest concentration also triggered an answer by the shoots' antioxidant enzymes with a decrease in the activity of superoxide dismutase and an increase in peroxidase. However, no significant change in catalase activity was observed, compared to the control group, which may indicate that peroxidase played a more crucial role against the oxidative stress than catalase. Combined results indicate that H. portulacoides was actively responding to a toxic effect imposed by this higher Ce concentration. Nevertheless, changes in normal environmental conditions, may increase the bioavailability of Ce, while in areas where acid mine drainage may occur, the highest Ce concentration tested in this study may be largely exceeded, placing the sustainability of halophytes and estuarine marshes at risk.
用水培法将滨藜属植物暴露在溶解态的铈中 5 天。尽管根和茎之间的转运因子（TF<0.01）非常低，但植物对铈的积累与培养液中铈的浓度增加有关。暴露于 300、600 和 1200μg/L 铈的植物根中铈的中位数浓度分别为 586、988 和 1103μg/g（干重），而茎中铈的中位数浓度分别为 1.9、3.5 和 10.0μg/g（干重）。尽管暴露于最高铈浓度的植物在第五天表现出明显的膨压丧失，但各组植物的根和茎长度均无显著差异。在 1200μg/L 的 Ce 处理下，观察到植物地上部分的过氧化氢和丙二醛水平升高。最高浓度还引发了植物地上部分抗氧化酶的应答，超氧化物歧化酶活性降低，而过氧化物酶活性增加。然而，与对照组相比，过氧化氢酶的活性没有明显变化，这表明过氧化物酶在抵御氧化应激方面比过氧化氢酶发挥了更关键的作用。综合结果表明，滨藜属植物对这种更高浓度的铈所产生的毒性效应积极作出了响应。然而，正常环境条件的变化可能会增加铈的生物利用度，而在可能发生酸性矿山排水的地区，本研究测试的最高铈浓度可能会大大超过，使盐生植物和河口沼泽的可持续性面临风险。
