Effect Of Dip Magnesium Sulfate Stress On Soil Properties And Microbial Communities

Ion rare earth ore are rich in strategic resources of medium and heavy rare earth.At present,the common soaking process is in situ soaking,and the soaking agent used is ammonium sulfate.After the soaking,there will be ammonium sulfate residue in the ore body,and ammonium sulfate will penetrate into the soil and groundwater with the rain erosion,causing the problem of ammonia nitrogen pollution in the mining area.At present,Jiangxi Province has begun to explore the use of magnesium sulfate as a new ammonium-free mining agent to reduce the ammonia nitrogen pollution in the mining area.Magnesium sulfate as a mining agent can achieve a better leaching effect,but the impact on the soil environment is not clear.In this paper,the new green ammonium free immersion agent magnesium sulfate was taken as the research object,and the soil of ionic rare earth ore area was taken as the extraction rate,the influence on the physical and chemical properties of soil microbial community structure were studied through indoor simulation experiments.The extraction effect of magnesium sulfate on ionic rare earth ore,the changes of soil properties and microbial community structure under different treatment conditions were analyzed,which provided theoretical basis for subsequent soil pollution treatment and ecological restoration in rare earth mineral areas.The main study findings are as follows:(1)The soil column leaching experiment showed that magnesium sulfate had a great effect on the soil physicochemical properties and enzyme activity.In the first 15 days,the soil p H increased with magnesium sulfate added,and the p H gradually decreased after 15 days.The ammonia nitrogen in the soil was lost by more than 90% in the first 8 days of the experiment,and the nitrate nitrogen content gradually increased with the progress of the experiment,but the higher the concentration of magnesium sulfate,the lower the nitrate nitrogen content.The organic matter loss in the soil on day 22 of the experiment reached more than 56%,and the effective phosphorus concentration was lower than the instrument detection line.The amount of cation exchange in the soil is proportional to the concentration of magnesium sulfate,but the amount of cation exchange is decreased at the last(more than10% on Day 50).The enzyme activity changes in the soil varies,with the addition of magnesium sulfate and the sucrase activity.Urease activity increased only when the magnesium sulfate concentration was higher(2%).This indicates that the loss of soil nutrients is serious after magnesium sulfate leaching is serious.(2)The extraction effect of magnesium sulfate varies for different metals.The extraction rate of magnesium sulfate on rare earth elements is above 94%,which is not much different from the extraction effect of ammonium sulfate.The magnesium in the soil increases greatly for 8 days before the dissolution,and the higher the concentration of magnesium sulfate,the greater the magnesium in the soil for 8-50 days will gradually decrease to the original magnesium content in the soil,indicating that there will not be a large amount of magnesium sulfate residual in the ore body.On day 50,the extraction rate of magnesium sulfate to aluminum in rare earth ore was more than 70%,indicating that the mother liquor produced by magnesium sulfate as a mining agent will also contain impurity aluminum.The iron extraction rate of magnesium sulfate on day 50 was below 10%.The potassium decrease in the soil for 50 days was 34%-38%.(3)The addition of magnesium sulfate changes the soil microbial community structure.The dominant population of the microbial community was mainly Proteobacteria,WPS-2,Chloroflexi,Acidobacteriota,Firmicutes,and Actinobacteriota,where unclassified k norank d Bacteria and Patescibacteria were newly detected classes due to magnesium sulfate stress.Elusimicrobiota The category that disappeared because of the stress of magnesium sulfate.The value of Ace index,Chao index and Sobs index increased,and the index value was highest at the concentration of 100 mg / kg,indicating that magnesium sulfate will increase the richness and diversity of soil microbial community.