Department of Environmental Geosciences, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 00, Prague - Suchdol, Czech Republic.
Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences Vienna, Konrad-Lorenz Strasse 24, 3430, Tulln, Austria.
Chemosphere. 2018 Jun;200:217-226. doi: 10.1016/j.chemosphere.2018.02.118. Epub 2018 Feb 20.
Characterisation of geochemical transformations and processes in soils with special focus on the rhizosphere is crucial for assessing metal(loid) bioavailability to plants during in situ immobilisation and phytostabilisation. In this study, the effects of nano zero-valent iron (nZVI) were investigated in terms of the immobilisation of As, Zn, Pb and Cd in two soil types and their potential uptake by plants using rhizobox experiments. Such system allowed monitoring the behaviour of trace elements in rooted and bulk soil compartments separately. Sunflower (Helianthus annuus L.) and ryegrass (Lolium perenne L.) were tested for As-rich (15.9 g As kg) and Zn-rich (4.1 g Zn kg) soil samples, respectively. The application of nZVI effectively lowered the uptake of all target risk elements into plant tissues. Efficient immobilisation of As was determined in the As-soil without a significant difference between plant and bulk soil compartments. Similarly, a significant decrease was determined for CaCl-available fractions of Zn, Pb and Cd in nZVI-treated Zn-soil. The behaviour of As corresponded to changes in Eh, while Zn and Cd showed to be mainly pH-dependent. However, despite the observed stabilisation effect of nZVI, high amounts of As and Zn still remained available for plants. Furthermore, the accumulation of the target risk elements in roots and the overall effect of nZVI transformations in the rhizosphere were verified and visualised by SEM/EDS. The following immobilising mechanisms were suggested: (i) sorption onto both existing and newly formed Fe (hydr)oxides, (ii) formation of secondary Fe-As phases, and (iii) sorption onto Mn (hydr)oxides.
特别关注根际土壤中地球化学转化和过程的特征对于评估原位固定和植物稳定化过程中金属（类）的生物可利用性至关重要。在这项研究中，通过根盒实验研究了纳米零价铁 (nZVI) 对两种土壤类型中 As、Zn、Pb 和 Cd 固定及其被植物潜在吸收的影响。该系统允许分别监测根系和土壤基质中痕量元素的行为。向日葵 (Helianthus annuus L.) 和黑麦草 (Lolium perenne L.) 分别用于富含 As（15.9 g As kg）和 Zn（4.1 g Zn kg）的土壤样本。nZVI 的应用有效地降低了所有目标风险元素进入植物组织的吸收。在没有植物和土壤基质之间显著差异的情况下，确定了在没有 nZVI 的 As 土壤中有效固定 As。同样，在 nZVI 处理的 Zn 土壤中，CaCl 可利用的 Zn、Pb 和 Cd 分数也显著降低。As 的行为与 Eh 的变化相对应，而 Zn 和 Cd 主要与 pH 有关。然而，尽管观察到 nZVI 的稳定化效应，但仍有大量的 As 和 Zn 对植物仍然可用。此外，通过 SEM/EDS 验证和可视化了 nZVI 在根际中的转化对目标风险元素在根系中的积累和整体影响。提出了以下固定机制：(i) 吸附到现有和新形成的 Fe (氢)氧化物上，(ii) 形成次生 Fe-As 相，和 (iii) 吸附到 Mn (氢)氧化物上。
