Institute of Soil Research, University of Natural Resources and Life Sciences Vienna, Konrad Lorenz-Straße 24, 3430, Tulln an der Donau, Austria; Institute of Agronomy, University of Natural Resources and Life Sciences Vienna, Konrad Lorenz-Straße 24, 3430, Tulln an der Donau, Austria; Soil Science Department, Faculty of Agricultural Engineering and Technology, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
Institute of Soil Research, University of Natural Resources and Life Sciences Vienna, Konrad Lorenz-Straße 24, 3430, Tulln an der Donau, Austria.
Environ Pollut. 2020 Nov;266(Pt 1):115088. doi: 10.1016/j.envpol.2020.115088. Epub 2020 Jun 29.
This work aimed to investigate the metal accumulation characteristics as well as biogeochemical changes in the rhizosphere and root foraging strategies of this plant species. Previous reports suggested that Noccaea rotundifolia ssp. cepaeifolia is a Zn, Cd and Pb hyperaccumulator. We used hydroponic, rhizobox and split-pot experiments for studying metal accumulation and related rhizosphere processes. Although this species accumulated up to 1250 mg Pb kg and 27,000 mg Zn kg in shoots, translocation factors <1 do not meet the hyperaccumulation criteria. Substantial increases in Ca(NO)-extractable metals in the N. rotundifolia rhizosphere of a metal-spiked soil can be explained by proton release from N. rotundifolia roots to maintain the charge balance during excessive metal uptake; this was not observed for the non-spiked, moderately contaminated control soil. Specific rhizosphere mechanisms targeting the alleviation of metal toxicity in N. rotundifolia rhizosphere were not detected. Generally, N. rotundifolia had larger total root and shoot mass in soils with heterogeneous distribution of Zn and Pb relative to homogeneous treatments, associated with less root mass placed in metal-enriched patches. However, the avoidance strategy was not reflected by low shoot metal concentrations. Metal accumulation rates and translocation factors do not meet the criteria for hyperaccumulation. Changes of pH and DOC in N. rotundifolia rhizosphere were apparently not involved in targeted immobilisation or detoxification of Pb, Zn and Cd. Avoidance of metal-rich patches in soil is a major tolerance strategy of N. rotundifolia.
本研究旨在探究该植物物种的金属积累特性、根际生物地球化学变化以及根系觅食策略。先前的研究表明，海韭菜（Noccaea rotundifolia ssp. cepaeifolia）是锌（Zn）、镉（Cd）和铅（Pb）的超积累植物。我们采用水培、根盒和分室实验，研究了金属积累及其相关根际过程。尽管该物种地上部可积累高达 1250 mg·kg-1 Pb 和 27000 mg·kg-1 Zn，但迁移系数 <1 不符合超积累标准。在添加金属的土壤中，海韭菜根际中可提取态 Ca(NO3)2-金属含量显著增加，这可以用过量金属吸收过程中质子从海韭菜根系释放来维持电荷平衡来解释；而在未添加金属、中度污染的对照土壤中则未观察到这种情况。在海韭菜根际中未检测到针对缓解金属毒性的特定根际机制。一般而言，与均匀处理相比，在 Zn 和 Pb 分布不均匀的土壤中，海韭菜的总根和地上部生物量更大，与在富含金属的斑块中放置的根质量较少有关。然而，这一避免策略并未反映在较低的地上部金属浓度上。金属积累速率和迁移系数不符合超积累标准。海韭菜根际 pH 和 DOC 的变化显然没有参与 Pb、Zn 和 Cd 的靶向固定或解毒。避免土壤中富含金属的斑块是海韭菜的主要耐受策略。
