Effect Of Modification Of Organic Materials On Cu Passivation And Soil Properties In Acidified Black Soil

Due to the unreasonable use of chemical fertilizers,chemical plant sewage discharge failure,natural precipitation,acid rain,etc.Soil acidification pollution in China is significant,seriously affecting the yield and quality of crops.In addition,Acidification will increase the activity of heavy metals in the soil and cause crops to absorb and accumulate more heavy metals.therefore,Heavy metal pollution in acidified soils needs urgent treatment.Research has shown that:Organic materials have a well-developed pore structure,special surface functional groups,and negative charges.It can improve soil physical and chemical properties,And it also has strong adsorption and fixing ability for metal ions.Make it less mobile and bioavailable in the soil,Reduce the effect of heavy metals contaminating the soil,and thus repair the biological toxicity of heavy metals on crops.At present,the research mainly focuses on the preparation of biochar using organic materials as raw materials.Compared with the modification,biochar has the disadvantages of high energy consumption,high cost,and inability to be prepared in large quantities.The passivation effect of the organic material itself is general,but through the modification treatment,the passivation effect of the organic material can be significantly improved.Therefore,in this study,Cu pollution acidified black soil in the plant area of the chemical plant was taken as the research object,and wood chips,corn stalks,and rape straw were used as raw materials to prepare modified organic materials.And through the indoor culture test to explore its passivation effect of Cu pollution acidified black soil.The main research results are as follows:(1)According to the modification test of organic materials,it is known that the soaking method and the soaking heating method all increase the cellulose content of the organic materials.The soaked heating method improves the cellulose content of the organic materials by about two times that of the soaking method.NaOH in the impregnation solution works best.The SEM results show that the surface structure of organic materials modified by NaOH soaking method(alkali soaking method)does not change significantly,while the maximum pore size of organic materials modified by NaOH soaking heating method(alkali thermal method)reaches 46.15 ?m,and the average pore size is approximately changed.3 times before sex.In summary,the alkaline heat method is used for the modification of organic materials.(2)According to organic material decomposing test,the organic material's decomposition rate increases with time.The organic material decomposes quickly before 21 days,and the decomposing rate reaches about 35% of the added amount.35 d of organic material decayed slowly,but there was also a tendency to increase.At this time,the decomposition rate of the three organic materials reached 40%.When the dosage of organic material was 5%,the passivation culture had the best passivation effect for 21 days,and the highest passivation rate reached 33.01%.It continued to increase the dosage and prolong the incubation time,and the Cu passivation rate changed.Not obvious.On this basis,organic materials and alkaline heat treatment of organic materials on the effective state of Cu content test,the results show that:Alkaline-thermal modification of sawdust,corn stover,and rape straw all decreased the available Cu content to varying degrees,and decreased by 9.19,5.43,and 5.50 mg/kg,respectively,compared to that before modification,in which the alkali-thermal method modified the bluntness of wood chips.The best results are achieved with a passivation rate of 39.99%.(3)Through the indoor constant temperature(25°C)culture experiment,the effects of sawdust and alkali-heat modified wood chips on total soil porosity,organic matter content and pH value were studied.Research indicates:Compared with the control(CK),sawdust and alkali-heat modified wood chips can increase soil total porosity,organic matter content and pH value,and all increase with the increase of the amount;wood chips and alkali are added in different proportions.The thermal modification of sawdust had no significant effect on total soil porosity and pH,but had a significant effect on soil organic matter content.Alkali-thermal method modified wood chips had the best effect.When alkali-heated wood chips were added,the proportion was 10 At %,the organic matter content increased by 45.8%.