Wind Tunnel Experimental Investigation On Dust Emission Characteristics Of The Chaganur Lake

As one of the four major freshwater lakes in Inner Mongolia,Chaganur Lake is an important ecological barrier in the arid and semi-arid transition zone.With the intensification of the global warming process,the amount of water in Chaganur Lake has decreased and it has become increasingly dry.Salt and alkali dust has appeared on the bottom of the dried lake,becoming a potential source of dust emission.Dust emission and secondary disasters caused by it seriously threaten regional ecology,environment and human health.At present,there is still a lack of deep understanding of the mechanism of dust emission,especially for the influencing factors on the emission of dust from the dry lake bottom.In order to reveal the characteristic mechanism and law of surface dust emission from the bottom of dry up Lake,this paper takes 12 kinds of soil samples at 4different locations in Chaganur Lake as research objects,Aiming at soil moisture content,particle size,salt content,crust thickness,and pH value,wind tunnel simulation experiments were conducted to study the dust emission process.Using PM30 concentration and sand collector flux as indicators,the main mechanisms and influencing factors of dust emission under different conditions,and the emission capacity of different soils were analyzed.The results show that:in the measurement of soil physicochemical properties,the soil sample belongs to the sand particle according to the soil particle size classification standard;the three kinds of soil samples in group C have the lowest water content;It is mainly composed of sodium chloride and sodium sulfate;The average thickness of the skin:Group C>Group A>Group D>Group B;the soil samples were strongly alkaline,so they were in line with the characteristics of saline-alkali land in Chaganur Lake.Between the dust entrainment rate and the shear stress,the three factors affecting the surface of group A are mainly the crust thickness,which is inversely related to the entrainment rate;the three surface entrainment rates of group C are negatively related to chloride ions,and carbonate ions There was a negative correlation;the entrainment rates of three types of surface in Group D showed a negative correlation with potassium ions,a negative correlation between carbonate ions and a positive correlation between sulfate ions.Between the saltation flux and the shear force,the three surface particle sizes in group A are negatively related to the saltation flux;the crust thickness and particle size values of the three surface groups in group C are negative related.The thickness,moisture content and pH of the three types of surface crust in group D were negatively correlated with the streamwise saltation flux,chloride ion was positively correlated with the saltation flux,and calcium ion and sodium ion were negatively correlated with the saltation flux.There is a power relationship between frictional velocity and entrainment rate(F=au_*~n)n ranges from 2-12;when the shear stress is large,the shear stress and the entrainment rate meet the linear law;when the shear stress is small,The shear stress and entrainment rate satisfy the exponential law;the threshold shear stress and the sulfate ion show a negative correlation.