Fractionation Of Rare Earth Elements In Soybean And Its Affecting Factors

Rare earth has been used widely in the traditional industry, such as metallurgy,engine,chemical industry and farming, etc. Because of its eximious characteristic ofimproving product capability and increasing crops output , REEs have become theresearch hotspot of first empoldering and developing elements in every country. Ourcountry has abundant REEs reserves, and the exploiture of REEs is given a highlyattention. Especially in the agriculture field, while the use and dosage of rare earthfertilizer highly increasing, the yield increasing and the quality improving alsoquicken the enrichment and accumulation of rare earth in the environment. After rareearth enter the environment, the uncertain environment effects of REEs and the REE'snegative influence on the entironment ,biology and human body have aroused manyscientist's attention recently, but the correlative study only just on the way. At thepresent time, the relative studies are mainly concentrated on the contents,environment chemical behavior and biologic effects, but less attention is paid to thefractionation of REEs in plants. Rare earth also belong to the heavy metal, Unlike other heavy metals, the REEscomprise of a series of elements with similar chemical properties, and the rare earthalways exist in symbiosis mode in nature. Regular fractionations of the REEs canoccur originated from the small but systemic differences of chemical propertiesamong these elements. So this characteristis always became the tracer elements foranatomising the forming reasons of rock or mineral. Studying this particularfractionating property to other heavy metal has very important significance forrevealing the translocation of REEs and other heavy metal in soil (solution)-plantsystems. This study also can provided athereunder consult for contaminative soil orwater from plant restore. Studying the fractionation of REEs in plant in nature is disturbed by theenviroment complexity of the soil and roots, so it is difficult to contrast and agree onthe same criterion. To overcome these shortages, the translocation, accumulation andfractionation of REEs in wheat are studied, and chemical and biological mechanismsresponsible for these behaviors are studied, through REE's determination by ICP-MS,REE speciation calculation by aqueous model, etc. This study is very important forrevealing the poisonous mechanisms of the organism by plant uptake the heavy metals,it also has very important guiding value. The summary of the study content is asfollow.1.Characteristics of REE accumulation and fractionation are observed in differentorgans of soybean via water culture. Under the conditions of adding extraneous REEs(the concentration of REEs is 10uM) and using solution culture methods, the experiment results show that: Theaccumulation of REEs were observed in the roots,stems and leaves of soybean, andthe majority of REEs are accumulated in roots of soybean( >91%), the third ternateleaves and conjoint stem have the higest concentration of REEs than other leaves andrelevant stem. The difference also exists in the single leaves of the ternate leaves insoybean. The middle single leaves have the highest concentration of REEs than othertwo single leaves. The analysis result show that the the concentration of REEsdecreased gradually from leafstalk to the brim of leaves in the annulus of middlesingle leaves. The character of the fractionation of REE in soybean is: The rootsexhibit middle REE (MREE) enrichment and M-shape variation (M-type tetrad effect).The stems and leaves show heavy REE (HREE) enrichment and W-shape variation(M-type tetrad effect). The third ternate leaves and conjoint stem have the highestaccumulation intensity of HREE than other leaves and relevant stem. Theaccumulation intensity of HREE of leaves higher than the stems. And light REEenrichment (LREE) is show in the fifth stems while notable enrichment of heavyREEs (HREEs) is found in the leaves. The accumulation intensity of HREE in themiddle single leaves increase graduly from leafstalk to the brim of leaves, and theleafstalk enr...