Anti-wind Erosion And Anti-dust Mechanisms Of Microbial Consolidation Of Bare Soil

Dust pollution has become one of the main forms of air pollution,especially in the northern regions of China.The large area of bare soil caused by insufficient urban greening combined with seasonal cultivation has become the main source of atmospheric dust.Researchers,domestic and overseas,have done a lot of research on their control measures.However,the existing dust prevention measures still have problems such as ineffective prevention and control,relatively high cost,or secondary pollution.Geotechnical microorganism technology is a new green and environmentally friendly new method for soil consolidation that has emerged in recent years,and can effectively prevent and control bare soil dust sources.The basic principle is to use the microbial mineralization reaction to generate carbonate precipitation to fill loose particles on the surface layer of cemented bare soil,expand the effective particle diameter and even form a hard shell layer on the surface layer,so as to achieve the purpose of suppressing wind erosion dust on the bare soil.At present,the research on anti-wind erosion dust of microbially consolidated bare soil is relatively few,and it is not systematic.This article first screened and cultivated microbial strains.Microbial consolidation samples are scanned by scanning electron microscope（SEM）,revealed the micro-consolidation mechanism.Wind tunnel test to study the ability of microbially consolidated bare soil to resist wind erosion and dust,and analyze its influencing factors.Analysis of ecological compatibility of microbial consolidation bare soil by studying changes of microbial consolidation soil properties and plant growth in consolidated soil.The main research contents of this article are as follows:（1）The effect of microbial consolidation on bare soil anti-wind and anti-dust was analyzed.Comparative analysis of wind tunnel tests on four types of bare soil dust source control measures,including microbial consolidation,dust-proof net covered,water-treated and original bare soil.It was found that under the same wind speed condition,the wind erosion mass loss of the sample by four prevention measures:microbial consolidation specimens<dust-proof net covered specimens<water-treated specimens<original specimens.Microbial consolidation of bare soil has the best resistance to wind erosion and dust.（2）The orthogonal test design was used to analyze the influencing factors of anti-wind and anti-dust of microbial consolidation bare soil.Through single-factor tests,it was found that the loss of wind erosion resistance,surface strength and calcium carbonate content of microbial consolidation specimens increased with the increase of bacterial solution concentration(OD₆₀₀),cementation solution concentration,and the number of consolidations,and decrease with the increase of particle size.The effect of soil sample porosity on wind erosion resistance of microbial consolidation specimens is small.When the number of consolidations reached 10 times.A large-scale hard shell layer has formed on the surface of the microbial consolidation sample,which makes it difficult for the solution to penetrate,resulting in a significant increase in the calcium ion content in the surface soil.（3）Reveals the micro-mechanism of microbial consolidation bare soil to anti-wind and anti-dust.SEM observation of microstructure of microbial consolidation specimens.The calcium carbonate precipitate generated by the microbial mineralization reaction first adheres to the surface of the soil particles to fill the pores.With the increase of calcium carbonate production,the soil particles near the cementation form a hard shell.The increased particle size of the soil on the surface of the bare soil or the formation of a hard shell can effectively suppress the wind erosion and dust of the bare soil dust source.The microstructure of microbial consolidation specimens with different particle sizes shows that the soil with smaller particle size of microbial consolidation has more obvious effect of increasing the surface soil particle size and aggregate size.When the microbial mineralization reaction is insufficient,the remaining calcium chloride solution in the cementation solution will also cement soil and form a very unstable aggregate in a dry state,which will be destroyed instantly under the action of hydraulic force.（4）Research the environmental compatibility of anti-wind and anti-dust of microbial consolidation bare soil.The p H value,soluble salt content and constituent elements of the microbial consolidation specimens were analyzed through experiments.It was found that the p H value and soluble salt content of microbial-consolidated bare soil samples only increased slightly,and the increased soluble salts were mostly unreacted calcium chloride solutions in the cementation solution.It is no harmful substances are generated and not cause damage to the soil environment.Analysis of plant growth in microbial consolidation soil revealed that plants grew well.This shows that microbial consolidation bare soil to inhibit dust sourse has certain promotion effect on plant growth.