Study On The Speciation Of REE In Soil And Its Application In Geochemistry

With blind exploitation of rare earth mines and wide application of rare earth elements in recent years,the amount of rare earth elements in soil environment increases year by year,which had serious effects on environment.Migration,transformation and biological availability of rare earth elements in soil were not only associated with its total amount,but with their forms.Therefore,it could provide theoretical basis for environment problems from the development of rare earth that knowing the existing form of rare earth elements in polluted soil.Two typical rare earth tailings reservoirs,respectially.Bayan Obo rare earth ore of Baotou and Gannan rare earth ore of Jiangxi were chose in the paper to study character of speciation and concentration distribution of rare earth elements in soil surrounded.In addition,potential ecological effects of rare earth elements were discussed.Established a method which was simple,convenient and suitable for mass analysis to ore and Soil.HCl-HNO3-HF-HClO4-H2SO4 under normal pressure was used in dissolving ore and polluted soil samples surrounded rare earth tailingsreservoirs,ICP-MS and ICP-AES were used in measuring rare earth elements.national reference material GBW07402,GBW07430,GBW07158,GBW07161 were used as quality monitoring,which verified the accuracy of the method and InductivelyBCR sequential extraction method for the sequential extraction of rare earth elements' chemical speciation was used in soil samples.On the basis of weak acid extractable experiment,ultrasonic extraction conditions were explored for samples Result of ultrasonic extraction was a bit poor than oscillationextraction,conditions of weak acid extractable that ultrasonicassisted were not yet ripe,large amounts of optimization experiments of conditions were needed.ICP-MS and ICP-AES were used in determination of 16 rare earth elements from sample BTK-1 of Bayan Obo rare earth ore and reference material GBW07161(collected from Longnan region of southern part of Jiangxi).BCR sequential extraction method was used in experiment of acid extractable of samples,results showed that the ore type of sample BTK-1 was rich of cerium,which belong to brown epidote.In this sample,the rare earth are in the form of ionic compounds occurrence in the crystal lattice,or as the isomorphism exist in the minerals,they showed low biological activity.However,the national reference material GBW07161 was ion-absorbing type rare earth ore,rare earth elements showed high biological activity.Results showed that sequential extractions of rare earth elements in contaminated soil were influenced by types of primary rare earth ores and natural environment conditions,extraction of rare earth elements in Baotou tailings reservoirs and Gannan tailings reservoirs of Jiangxi were largely residual state and reduced state respectively.Result of ultrasonic extraction was a bit poor than oscillationextraction,conditions of weak acid extractable that ultrasonicassisted were not yet ripe,large amounts of optimization experiments of conditions were needed.The rare earth elements in five soil samples were higher than the average in national soil,the closer the mine,the higher the rare earth concentration,the more serious pollution.The weak acid extractable and reducible of Rare Earth Elements in Jiangxi soil much larger than the proportion of Baotou soil,indicating that within the experimental range,Jiangxi Rare Earth Elements in soil more easily absorbed and utilized by plants,soil potential ecological risk is higher than the header.This paper offered scientific basis for the discussion of ecological effects on environment,evaluating environmental risks and taking countermeasures of the development of rare earth resources.