Schwabe Franziska, Tanner Simon, Schulin Rainer, Rotzetter Aline, Stark Wendelin, von Quadt Albrecht, Nowack Bernd
Soil Protection, Institute of Terrestrial Ecosystems, ETH-Zurich, Universitaetstrasse 16, CH-8092 Zurich, Switzerland.
Metallomics. 2015 Mar;7(3):466-77. doi: 10.1039/c4mt00343h.
We investigated the uptake of cerium (Ce) dioxide nanoparticles (NPs) by hydroponically grown wheat, pumpkin and sunflower plants. The presence of plant roots in nutrient solution led to a substantial increase in the dissolution of CeO2-NP compared to plant-free medium. Experiments with Zr/CeOx-NP revealed that Ce was not only taken up in the form of NPs, but simultaneously to a significant degree also as dissolved Ce(iii) ions, which then re-precipitated in the form of CeO2-NPs inside the leaves. The contribution of dissolved Ce uptake was particularly large for particles smaller than 10 nm due to their higher dissolution rate. Our data also indicate that the translocation of Ce resulting from NP-root-exposure is species dependent. When Ce was supplied as dissolved ions, sunflower had the highest capacity of Ce-ion accumulation inside the leaves, while there was no significant difference between pumpkin and wheat. We found no Ce translocation from roots into shoots when only NPs bigger than 20 nm were applied. This study highlights that plant root activity can have a significant impact on the dissolution of CeO2-NPs in soil solution and that uptake of dissolved Ce(iii) followed by re-precipitation needs to be considered as an important pathway in studies of CeO2-NP uptake by plants.
我们研究了水培种植的小麦、南瓜和向日葵植物对二氧化铈纳米颗粒（NPs）的吸收情况。与无植物的培养基相比，营养液中植物根系的存在导致CeO2-NP的溶解大幅增加。对Zr/CeOx-NP的实验表明，铈不仅以纳米颗粒的形式被吸收，同时在很大程度上还以溶解的Ce(iii)离子形式被吸收，这些离子随后在叶片内以CeO2-NPs的形式重新沉淀。由于小于10nm的颗粒具有较高的溶解速率，因此溶解态铈的吸收贡献尤为显著。我们的数据还表明，由于纳米颗粒与根系接触导致的铈转运具有物种依赖性。当以溶解离子形式供应铈时，向日葵在叶片内积累铈离子的能力最强，而南瓜和小麦之间没有显著差异。当仅施用大于20nm的纳米颗粒时，我们未发现铈从根向地上部的转运。本研究强调，植物根系活动会对土壤溶液中CeO2-NPs的溶解产生重大影响，并且在研究植物对CeO2-NP的吸收时，溶解态Ce(iii)的吸收随后重新沉淀应被视为一条重要途径。
