Study Of Form Distribution Of Exogenous Rare Earth In Main Agriculture Soils Of Anhui

Rare earth(RE) have used widely in the traditional industry,such as metallurgy, engine,chemical industry and farming,etc.Because the eximious characteristic of improve product capability and increase crops output,RE have become the study hotspot of first empolder and develop elements in every country.Our country have abundant RE reserves,also the exploiture of RE are given highly attention.Especially in the agriculture field,while the yield increasing and the quality improving as the use and dosage of rare earth fertilizer highly increasing,it also quicken the enrichment and accumulation of rare earth in the environment.The environmental behaviors of RE determined mainly by the form but not of the gross of RE,it has practical theoretic guidance significance.This experiment studies on the main agriculture soil of Anhui in the dry and submergic condition.Using the BCR extraction procedure to study the time course of exogenous La and Nd,to know the existing form and disciplinarian of transference and transformation after the exogenous RE enter into the soil.The experiment has five disposal 0(control disposal ),5,15,50,100mg/kg and 1350 soil samples.It cultivated in dry and submergic condition in constant temperature, controlling the same humidity of dry cultivation and inundation condition of submergic cultivation.It'begins to sampling from the 1 th,6th,11 th,17th,22th,30th, 60th,120th,day(submergic condition from 6th day),and conduct form extraction, meanwhile amount of containing water shoule be mensurated.The amount of RE in the extaction liquid mensurated by the ICP-AES.The transference and transformation of RE in soil affected by kinds of environmental factors and the physical and chemical properties of experimental soil itself,such as pH,Eh,adsorption capacity of soil,the content of iron and manganese oxide and organisms,will affect the distribution of exogenous RE.The result of study as following:1.The distribution difference of exogenous La among three kinds of soils. In dry and submergic condition,the concentration sequence of B1 form in three kinds of soils is:Yellow-red soli＞Yellow cinnamon soil＞Vertisol.The concentration sequence of B2 form is:Yellow-red soli＞Yellow cinnamon soil＞Vertisol.Whether the dry or submergic condition,the form of B3 in Yellow-red soli is always lowest, there have no obvious relationship between Yellow cinnamon soil and Vertisol.2.The distribution difference of exogenous Nd among three kinds of soils. In dry condition,the available form is highest of lower concentration disposal of exogenous Nd in Yellow-red soli,and then taper;the B1 form is always highest of higher concentration disposal of exogenous Nd in Yellow-red soli.In submergic condition the B1 form is always highest in Yellow-red soli.In dry and submergic condition,the B1 form of exogenous Nd is always lowest,but at the late of experiment will unbind in Yellow cinnamon soil and Vertisol.In dry and submergic condition,the concentration sequence of B2 form is:Yellow-red soli＞Yellow cinnamon soil＞Vertisol.At the late of experiment,the B2 form of exogenous Nd will decrease gradually in Yellow-red soli and Yellow cinnamon soil, but the B2 form of exogenous Nd will increase slightly.In dry and submergic condition,the transformation of B3 form of lower concentration disposal have no disciplinarian;in the condition of high concentration disposal, Vertisol and Yellow cinnamon soil have the similar transformation trendency,and generenlly the concentration is higher than Yellow-red soli.3.In three kinds of soils,exogenous La and Nd have the similar transformation trendency.Whether the dry or submergic condition,the concentration of B2 and B3 form of exogenous La is higher than the concentration of B2 and B3 form of exogenous Nd in Yellow cinnamon soil and Vertisol,in Yellow-red soli,the concentration of B1 and B2 form of exogenous La is higher than the concentration of B1 and B2 form of exogenous Nd,but the concentration of B3 form of exogenous Nd is higher than the concentration of B3 form of exogenous La.4.Exogenous La and Nd accumulate in the B2 and B3 form in Yellow-red soli,but in Yellow cinnamon soil and Vertisol,exogenous La and Nd accumulate in B3 form,and the concentration of B2 form is lower relatively.