The Effects Of Bentonite On Immobilization Remediation Of Soils Contaminated By Cadmium

With the development of industry,the degree of soil heavy metalpollution is increasing. Cadmium ranked sixth as toxic substances endangering humanhealth through the food chain enrichment and endanger human health. Throughreducing the phytoavailability of cadmium，Soil heavy metals in-situ immobilizationremediation technology can reduce heavy metals in plant, animal and human hazardswith the advantages of low cost, high efficiency.In order to provides theoretical basis and technical support for Cd pollutioncontrol in soil, use pot experiment to study the effects of bentonite on physiologicalbiochemical characteristics of rice under cadmium contamination condition, with potexperiment and plot experiment to study the effects of bentonite on Cd contents indifferent parts of rice,on rice yield of each cell, and,on speciation of cadmium in soiland on soil environment.From the pot experiment, with bentonite， the content of chlorophyllincrease,POD enzyme activity was significantly decreased (P <0.05), MDA contentdecreased significantly (P <0.05), the activity of SOD increased, the bentonite canreduce the accumulation of free radical, reduce stress effect of cadmium on plant cells.With the increase of bentonite fertilizer, increased the soluble protein contentdecreased, indicating that the concentration of bentonite could reduce the cadmiumion in plants. Bentonite on cadmium pollution of soil can effectively reduce thetoxicity of cadmium in plant cells, improve plant resistance to reverse environments.After bentonite addition， plot rice yield and potted rice biomass increasedsignificantly. Bentonite could reduce the cadmium content in different parts of rice,results more obvious on roots. For Pot experiment,2mg/kg cadmium treatmentconditions, with3%or5%bentonite,5mg/kg cadmium treatment conditions, with5%bentonite, the Cd content in brown rice in line with national standards of foodhygiene.For Plot experiment, bentonite can effectively reduce the cadmium contentin brown rice, but not as effective as potted processing. Bentonite can effectivelyreduce the migration of cadmium in soil， reduce the absorption of plants to cadmium,reduce the toxic effect of cadmium on plant. For plot and pot experiment, bentonite can reduce the decomposition rate oforganic matter, thereby reducing the urease and invertase activity. The urease andinvertase activity in pot experiment were significantly decreased (P <0.05), indicatebentonite can reduce soil nitrogen supplying capacity. Bentonite can significantlyimprove catalase activity in cadmium pollution soil (P <0.05), reduce the heavymetal stress effects on plant damage, increase plant resistance. Due to the highconcentration of bentonite is toxic to microorganisms, soil microbial quantityreduction．...