The Research On The Spatial Distirbution And Treatment Effect Of Chemical Contaminants In Rare Earth Tailings

In recent years, the pharmaceutical processing residues in Rare Earth tailings mine caused moreserious chemical pollution problems to tailing area and the surrounding areas in Ganxian county, JiangxiProvince. However, the current research at home and abroad concentrates on environmental pollutionproblem of heavy metals and radioactive elements, but seldom focus on chemical pollution of RareEarth tailings mine.This paper made the soil of Rare Earth tailings mine inYangBuXiang、DaTianXiangand HanFangXiang Ganxian county as the research object, analyzed the residual state of soil pH、NH₄⁺and SO₄^2-in the above three areas, especially their spatial distribution on the bare tailing area ofYangBuXiang that is the most polluted places.At the same time,the effect that different ages ofEucalyptus plantation and Bambusa rigida forest remove chemical contaminants and improve thephysical and chemical characteristics of soil was researched by the contrast analytical method. The mainresearch results were as follows：（1）According to the residual state analysis of chemical contaminants, indicating that averagecontents of soil pH,NH+-4and SO24were4.27,2.69mg/kg,7.44g/kg,and none meet standards of localcontrol values(pH5.24,NH₄⁺0.1mg/kg,SO₄^2-2.50g/kg).The residual quantity of NH₄⁺exceed as14timesas local control values is maximum in the soil；Contents of soil pH,NH₄⁺and SO₄^2-in most samples wasover the standard and it shew that the the chemical contaminants were still in the most areas; Coefficientof variation（C.V.） of chemical contaminants was in the order of NH+2-4＞SO4＞pH, NH₄⁺and SO₄^2-allbelong to medium variability with theirC.V being more than50%,.while pH was relatively weak withC.V being13%.（2）Comparative analysis of different sampling area and different depth of soil pollutants contentindicated that The residual quantity of chemical contaminants on bare tailing area was largest,andcontent of chemical contaminants in topsoil was larger than the bottom layer of the soil.（3）Correlation analysis shew that soil pH exhibit significant negative correlations with NH₄⁺andSO₄^2-,suggesting that the higher the NH₄⁺and SO₄^2-, the lower the pH,and the stronger the acidsoil,while NH₄⁺exhibit significant positive correlations with SO₄^2-.（4） Through analysis of the spatial distribution of pollutants on the bare tailing area, the followingconclusions were made:there was a large spatial variation on the bare tailing area; The content of soilpollutants in tailings pile was greater than downstream groove tailings,and each pollutant content in thesubsoil wre greater than the upper soil showing that tailings pile was one of the most seriously pollutedareas of Rare Earth tailings mine areas.（5） The study that Eucalyptus plantation and Bambusa rigida forest removed chemicalcontaminants indicat: the effect that Eucalyptus plantation remove chemical contaminants is obvious,especially in0²0cm soil layer with removal rate of NH₄⁺and SO₄^2-being75%、85%,and soil pHincrease with the age of the shrubs; at the same time, Bambusa rigida forest had a good effect on NH+4removal which was more than85%, but had nothing to do with SO₄^2-; in addition, Bambusa rigida foresthas certain effection on soil pH. （6） Influence research of pollutants treatment on the physical and chemical properties of soil：Eucalyptus plantation and Bambusa rigida forest played a role in improving the physical and chemicalproperties of soil which could lower soil volume weight, improve soils moisture content, porosity,organic matter and soil nutrient contentst. Furthermore, with the the growth of forest age, theimprovement is more significant,but soil available potassium contents were always detracting.