Study On The Effect Of Yttrium And Leaching Agent Ammonium Sulfate Stress On Soil Physicochemical Properties And Microbial Communities

This paper,taking farmland soil arounding Longnan mining area with a large content of yttrium?Y?polluted by ore leaching mine process and campus as the research background and material,sespectively,studied the influence of different concentrations of rare-earth yttrium and ore leaching ammonium sulfate[?NH₄?₂SO₄] on soil physical and chemical properties and microbial population structure by indoor simulation and analyzed the change of soil properties and the difference of soil microbial community structure under different processing conditions.The results showed that it was hazard that rare earths enrichment and the emissions of residual ore leaching agent in process of in-situ leaching ore mining rare earth ore to the soil fertility and microorganisms,providing scientific basis for the assessment and ecological restoration of soil pollution in rare earth mining area.The stress of single and composite to soil pH,available phosphorus,alkali solution N,available K and organic matter was studied by indoor simulation experiments,combining physical and chemical properties of soil analysis methods and SPSS software.The results showed that single stress and combined stress of Y,?NH₄?₂SO₄ led to lower soil pH,but compared to a single stress,decreasing of soil pH eased under combined stress.Available phosphorus is as follows: under single stress,phosphorus had no significant change at lower concentrations of Y or?NH₄?₂SO₄;when the concentration of Y or?NH₄?₂SO₄ reached 500 mg/kg,phosphorus began to decline sharply;while changes in soil available phosphorus was different under combined stress,and,for two different composite stresses of fixed concentration of?NH₄?₂SO₄ with Y changing and fixed Y concentration with?NH₄?₂SO₄ changing,changes of soil phosphorus were not the same as well.Both single stress and combined stress of Y,?NH₄?₂SO₄ promoted to soil nitrogen increasing with variable concentrations of rising.Soil available K and organic matter were showed reduced after the first rise under single stress and combined stress had the opposite phenomenon,generally showed declined first and ascended.Correlation analysis showed that,The degree of correlations between different soil factors in different culture time were changed,however,soil available phosphorus and organic matter always showed strong correlation.Besides,the relationships of soil organic matter content,nitrogen and available phosphorus were close under single stress,while changes of available K was relatively independent;for combined stress,soil available phosphorus,available K and organic matter content had close relationships.The changes of soil microbial community structures under single stress and combined stress of Y and?NH₄?₂SO₄ were studied by Illumina MiSeq high-throughput sequencing technology.The results showed that The dominant populations of soil microorganisms at division level were Proteobacteria,Firmicutes,Bacteroidetes,Planctomycetes,Actinobacteria,Chloroflexi,Verrucomicrobia,Gemmatimonadetes and Acidobacteria at both single stress and combined stress,but the relative abundance of bacteria in each soil samples changed with Y concentration or?NH₄?₂SO₄ concentration.When Y or?NH₄?₂SO₄ concentration was too high??1000 mg/kg?,Firmicutes increased a lot at single stress and the proportion of other groups reducing,but microbial community structure changes vary greatly at combined stress.the high concentration of Y or?NH₄?₂SO₄ stress?Y?1000 mg/kg,?NH₄?₂SO₄?500 mg/kg?caused the soil microbial species richness decreased,but high concentrations of combined stress of increased the species abundance.In addition,Pearson correlation analysis and RDA analysis showed environmental factors had a great impact on soil microbial community structure changes under Y and?NH₄?₂SO₄ stresses.Wherein,p H,available phosphorus,organic matter were important factors affecting bacterial community structure under Y stress;available K could affect the bacterial community structure,but not significant factor under?NH₄?₂SO₄ stress;the important factors affecting the bacterial community structure were available phosphorus and potassium under both combined stress.