Effect Of Rare Earth Elements In The Soil Of Ionic Type Rare Earth Mining Area

Aiming at the soil pollution problem of nitrides caused by rare earth mining in the mining area in southern of Jiangxi province and in order to explore the relationship between the soil pollution and the rare earths,the soil in rare earth ore mining area was taken as the research object.The soil column device was made to complete it.Firstly,the effects of endogenous rare earth elements on the distribution of nitrogen in soil were studied by the simulated rainfall leaching experiment.Secondly,the effects of rare earth elements on the content of nitrogen in the upper and lower layers were studied by adding rare earth elements with different kinds and concentrations.Finally,the interaction mechanism between rare earth elements and nitrides and the mechanism of the conversion of nitrides were discussed.The following conclusions were drawn:(1)In the erosion of the leaching water,ammonium nitrogen in raw soil profiles was soaked at about 500 mg/kg.This value was from 350 to 1300 mg/kg in campus soil profile.Ammonium nitrogen in wet quantity in campus soil was significantly greater than in raw soil.This is because the presence of rare earth elements in raw soil have strengthened the ability of nitrogen fixation of soil.The migration rate and quantity of the nitrate nitrogen in raw soil were greater than in campusl soil.(2)The effects of adding different concentrations of exogenous yttrium oxide,lanthanum oxide and mixed rare earth on the ammonium nitrogen in raw soil were same.The lower concentration of exogenous rare earths would promoted the ammomium content,while higher concentration inhibited.The larger peak of yttrium oxide to the ammonia content was preliminary determinated at 5-10 g/kg.The peak value of adding lanthanum oxide was between 0 g/kg to 1g/kg,and so as to the mixed rare earth.(3)The addition of yttrium oxide with different concentration into the raw soil was not significant to the nitrate nitrogen content in soil.Adding lanthanum oxide showed inhibition on nitrate nitrogen in upper and lower soil.Adding different concentrations of mixed rare earth into the soil made a difference to the nitrate nitrogen content.The lower mixed rare earth concentration would promote the nitrate nitrogen content.However,the higher would inhibit.(4)Under the condition of adding different concentrations of exogenous yttrium oxide,lanthanum oxide and mixed rare earth,the change trendency of available nitrogen is same with theammonium whether in the upper soil or lower ore soil.The ammonium is the main form of the avaliable nitrogen.And the addition of rare earth elements may affect the conversion way and the rate.(5)The mechanism of interaction between rare earth elements and nitrides was mainly the exchange reaction between rare earth ions and ammonium ions.However,the conversion of nitride would occur under the external conditions.