Faculty of Environmental Sciences, VNU University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam.
Faculty of Environmental Sciences, VNU University of Science, Vietnam National University, Hanoi (VNU), 334 Nguyen Trai, Thanh Xuan, Hanoi, Viet Nam; Institute for Nuclear Science and Technology, 179 Hoang Quoc Viet, Hanoi, Viet Nam.
J Environ Manage. 2019 Nov 1;249:109423. doi: 10.1016/j.jenvman.2019.109423. Epub 2019 Aug 23.
The formation of phytoliths as a result of the precipitation of Si in many Si-rich plant species is known to encapsulate organic matter. This work aims to examine the possible encapsulation of Cu in grass phytoliths in an orange growing area, where Cu-rich fungicides have been excessively applied. Batch experiments, in combination with SEM-EDS and microscopy, were conducted for the grass-derived phytoliths and phytoliths separated from soil, thus revealing their dissolution properties, morphotypes and contents, in relation to soil properties. By measuring the Cu release accompanying the dissolution of phytoliths by different extractants, especially an NaCO/HNO solution, it was revealed that Cu was encapsulated within the silica body of the phytolith. This sink of Cu in the grass can be cycled to serve as a new Cu source in soils. Phytolith contents in the soil were up to 17.7 g kg and tended to accumulate in soil depths from 0 to 20 cm. A positive correlation was found for soil phytolith and phytCu contents and may be indicative of the role of phytoliths as an enhancer of Cu accumulation in soil. It would be worth developing suitable techniques for the determination of phytCu, because common extraction/digestion methods are not suited for evaluating this Cu pool.
植物硅酸体的形成是由于许多富含硅的植物物种中硅的沉淀，已知它可以包裹有机物。本工作旨在研究在一个过度使用富铜杀真菌剂的橙种植区，草类植物硅酸体是否可能包裹铜。通过批量实验，结合扫描电子显微镜-能谱仪（SEM-EDS）和显微镜，对源自草类的植物硅酸体和从土壤中分离出的植物硅酸体进行了研究，从而揭示了它们与土壤特性相关的溶解特性、形态和含量。通过测量不同提取剂（特别是 NaCO/HNO 溶液）伴随植物硅酸体溶解时释放的 Cu，可以发现 Cu 被包裹在植物硅酸体的二氧化硅体中。这种草类植物硅酸体中 Cu 的汇可以循环利用，成为土壤中 Cu 的新来源。土壤中的植物硅酸体含量高达 17.7 g/kg，且倾向于在 0 至 20 cm 的土壤深度中积累。发现土壤植物硅酸体和植物 Cu 含量之间存在正相关，这可能表明植物硅酸体在促进土壤中 Cu 积累方面发挥了作用。值得开发合适的技术来测定植物 Cu，因为常见的提取/消解方法不适合评估这种 Cu 库。
