Study On Remediation Of Mercury Contaminated Soil Remediation By Fulvic Acid Combined With Stabilizers

Curing/stabilizing repair is the main technology for the restoration of mercury pollution in heavy metal soils.Green repairing agents are one of the hot issues.In this paper,mercury-contaminated soil is used as an example to investigate biochemical fulvic acid（BFA）and ore-derived fulvic acid（MFA）,as well as fulvic acid combined with sodium sulfide（Na₂S）,sodium thiosulfate（Na₂S₂O₃）,and six partial biases.The effect of sodium phosphate(Na₆P₆O₁₈)three stabilizers on the repairing effect of mercury-contaminated soil.The main conclusions are as follows:1.Repair of mercury-contaminated soil by adding fulvic acid alone（1）The effect of BFA added with mass fraction of 5%on soil mercury pollution was significantly better than that of BFA with 2%mass fraction（p<0.05）.And the addition of BFA will cause the soil to show a decrease in pH first and then increase,and the soil conductivity will increase first and then decrease.On the third day of culture,the leaching value of soil mercury concentration can be significantly reduced（p<0.05）.It is characterized by water-soluble mercury,iron-manganese oxide-bound mercury,and reduced residual mercury.Exchangeable mercury,carbonate-bound mercury,and organic-bound mercury increased.（2）The effect of MFA added with mass fraction of 5%on soil mercury pollution was better than that of MFA with 2%mass fraction,but there was no significant difference between the two（p>0.05）.The soil as a whole showed a decrease in pH and a trend of first increase and then decrease in soil conductivity.On the 7th day of culture,the leaching value of soil mercury concentration was significantly reduced（p<0.05）,and the form of mercury in soil was characterized by water-soluble mercury and exchangeable.Mercury,carbonate-bound mercury,organically bound mercury decreased,iron-manganese oxide bound mercury,and residual mercury increased.（3）The addition of BFA reduced the soil leaching value faster than the addition of MFA.The addition of BFA reduced the combined mercury content of iron-manganese oxide and the highest content of organic binding in soil mercury.The addition of MFA allowed the combination of iron-manganese oxide in the experimental soil.The mercury content increased,and the residual mercury content in the soil mercury form was the highest.2.Simultaneous application of fulvic acid combined with stabilizer to the repair of mercury-contaminated soil（1）The application of fulvic acid-binding stabilizer has a positive effect on the recovery of mercury pollution in soil than the direct addition of fulvic acid,which can significantly reduce the leaching value of soil mercury concentration（p<0.05）and promote the active state of soil mercury(water-soluble state,The exchangeable state,the carbonate-bound state,and the iron-manganese oxide-bound state are converted to a stable state（organic bound state,residual state）.（2）The pH changes of BFA and MFA combined with Na₂S and Na₆P₆O₁₈8 in the culture cycle showed a trend of decreasing first and then increasing.The pH of BFA and MFA combined with Na₂S₂O₃ increased during the culture period.BFA and MFA combined with three stabilizers increased soil conductivity during the culture cycle.（3）The effect of BFA and MFA combined with three stabilizers on soil mercury pollution has a tendency to increase with the increase of S/Hg within a certain range.In general,the repair effect is better when S（P）/Hg=5,but the specific performance is that BFA and MFA combined with Na₂S have the best soil remediation effect at S/Hg=10,and BFA combined with Na₂S₂O₃ in S/Hg=10 pairs.The effect of mercury-contaminated soil remediation is inhibited.（4）Both BFA and MFA achieved the highest stability rate of soil leaching value on the 7th day of culture,and the stability effect of BFA combined stabilizer on soil mercury leaching value was better than that of MFA joint stabilizer on soil mercury leaching value.3.The application of fulvic acid combined with stabilizers to the repair of mercury-contaminated soil（1）Compared with the fulvic acid combined with stabilizer,the effect of fulvic acid combined with stabilizer on the soil remediation effect on mercury-contaminated soil is generally the best to shorten the soil mercury leaching concentration.Stabilizer dosage for good stability time.Specifically,the fulvic acid combined with the stabilizer is applied sequentially on the 7th day of culture,that is,the fourth day of the application of the stabilizer has a better stabilizing effect on the mercury leaching value of the soil,and the stabilizer S（P）/Hg is applied significantly lower.The state was simultaneously applied to the fulvic acid and the stabilizer（p<0.05）.（2）BFA combined with Na₂S has the best effect on soil mercury pollution repair in S/Hg=5,but there is no significant effect of BFA combined with three stabilizers on soil mercury pollution repair effect and MFA combined with three stabilizers on soil mercury pollution.Difference（p>0.05）.（3）The sequential application of fulvic acid combined with stabilizer at the end of the culture period is slightly greater than the effect of fulvic acid combined with stabilizer on soil pH and conductivity,but there is no significant difference.（p>0.05）.