Effect Of Modified Coke Based Modifier On Saline Alkali Soil

Shanxi Province is located in the eastern part of the Loess Plateau.A large amount of saline-alkali land is formed under the influence of terrain,topography and climate.Saline-alkali soil has high p H and salt content,poor air permeability and water permeability,and low fertilizer efficiency,which adversely affects the growth of crops.The activated coke used in this study is the waste after flue gas desulfurization and denitration,which has the characteristics of acidity and porous structure.AM fungi can form a symbiotic relationship with plant roots,thereby promoting plant roots and survival under adversity conditions.In this thesis,the physical and chemical properties of activated coke waste and the risk of heavy metals are studied.On this basis,the improvement effect of activated coke waste and its combination with arbuscular mycorrhizal fungi(AM fungi)on saline-alkali soils is explored.The main findings are as follows:(1)The active coke has a high salt content,and HNO₃ is used to acidify and modify it.The physical and chemical properties and environmental risks of the active coke before and after modification are investigated.The research results show that:compared with the activated coke before modification,the conductivity of the modified activated coke is reduced by about 15 times,the S content is reduced by 57.1%,and the specific surface area is increased by 36.0%.The content of heavy metals Cr,Cu,Pb,Zn,Ni,and As in activated coke is far lower than the standard limit of organic-inorganic compound fertilizer and the soil environmental quality standard.Activated coke heavy metals mainly exist in residue state and organic sulfide combined state,accounting for 55%-100%and 6%-42%.Respectively,indicating that most of the heavy metals are difficult to absorb by plants.The leaching of heavy metals of activated coke under different p H conditions did not exceed the standard limit of organic-inorganic compound fertilizer,and the leaching of heavy metals of activated coke after modification was lower than that of activated coke before modification.Compared with the activated coke before modification,the salt content of the modified activated coke is reduced,and the content of heavy metals meets the environmental risk standard,so it can be used for agricultural resource utilization.(2)Through pot experiment,the effect of applying before and after modified activated coke on the improvement of saline-alkali soil and the influence of plant growth were explored(CK,0g·kg^-1;A10,10g·kg^-1;A20,20g·kg^-1).The results showed that:compared with the blank,after applying the modified active coke,the salt content of the soil increased,the biomass of the plant was not significantly different,and the content of superoxide dismutase(SOD)and total P of the plant decreased.Compared with the blank,the salt content of activated coke soil decreased by 6.8%?26.5%,the biomass of plants increased by 52.9%,the chlorophyll content of plants increased by 12.3%?13.0%,and the relative water content of plants increased by 7.0%?10.4%,plant SOD increased by 1.5%?2.7%,plant total N content increased by 2.6%?17.7%,plant total P content increased by21.6%?23.2%.The above results show that the modified activated coke in saline-alkali soil has better effect than the activated coke before modification.The modified activated coke reduces the salt content of saline-alkaline soil,promotes photosynthesis and nutrient absorption of plants,and promotes plant growth and development.(3)Based on the research of(2),select modified activated coke and AM fungi to prepare activated coke-based modifiers,and explore its effect on saline-alkali soil improvement and plant growth through pot experiments..The results showed that compared with the blank,the modified activated coke and AM fungus combined application soil p H decreased by 2.4%,total salt content decreased by 22.4%,SAR decreased by 6.0%,CEC increased by 8.6%,organic matter content increased by 150.3%,total N content increased by 76.2%,hydrolyzable N content increased by 82.4%.The combined application of modified activated coke and AM fungi increased plant biomass,root-shoot ratio,plant height,enzyme activity and N and P content,and reduced the electrolyte extravasation rate of plants.The above results indicate that the combined application of modified activated coke and AM fungi reduces the salt content of the soil,increases the nutrient content of the soil,and then promotes the absorption of N and P by the plants to ensure the nutrients required for plant growth and development.This research provides a new method for the comprehensive utilization of solid waste and environmental remediation.