外源稀土对根际稀土和重金属地球化学行为的影响

利用根箱装置并运用ICP—AES分析技术，通过添加外源稀土研究了土壤中不同稀土含量下稀土元素La、ce、Nd、Pr和Y以及重金属元素Fe、Mn、Zn在油菜根际的动态迁移过程，并结合根际pH及油菜根系稀土和Fe、Mn、zn含量的变化，探讨了外源稀土对根际稀土和重金属地球化学行为的影响。结果表明，随稀土处理浓度的升高和培养时间的延长，稀土和Fe、Mn、zn离子在根一土界面趋于累积，高浓度稀土处理累积显著，同时根际pH出现降低；根际影响范围稀土仅2mm，Fe、Mn、zn达到6mm。油菜根系稀土含量随稀土处理浓度的升高而升高，Fe、Mn、zn的含量变化相反。分析表明，在研究农用稀土在土壤一植物系统中的环境效应时，根际效应不容忽视。

Influence of Extraneous Rare Earth Elements (REE's) on Biogeochemical Behaviors of the Elements and Several Other Metals in Rhizosphere

Translocation and absorption of ra re earth elements and heavy metals Fe,Mn,Zn as well as changes of pHin rhiz osphere of rape were studied by applying extr aneous rare earth elements(REEs )into soil using a rhizobox device and ICP -AES analysis technology.The influence of extran eous rare earth elements on biogeoch emical behaviors of the elements and several heavy metals in the rhizosphere were presented.The results showed that REEs and Fe,Mn,Z n had a trend to enrich in the rhizosph ere with the enhancement of the contents of extra neous REEs and exposure duration.The enrichment in the rhizosphere with the treatment of high dose was remarkable while pH value decreased.The range influenced by activity of roots was about 2mm from root surface to REEs and reached 6mmto heavy metals.The c ontents of REEs in the root of rapes in creased with the concentrations of extraneous REEs but that of Fe,Mn,Zn just reversed.The p resent study indicated that the effe cts from rhizosphere were not neglec ted when evaluating environmental impact of REEs in soil-plant ecosystem.