Experimental Research On Carbonate Rock Erosion By The Maocun In Guilin

The increase in atmospheric CO₂ content has brought an unprecedented crisis to the global environment.Since the 1990 s,scholars have found that the atmospheric CO₂ content recovered by karst accounts for about 30% of the global carbon cycle omission sinks.Quantitatively studying the dissolution rate of carbonate rocks can more objectively evaluate the degree of karst development in the study area,and provide scientific basis for exploring the karst topography and landscape development in the study area.This paper takes the Maocun underground river basin of Guilin City as the research area.Based on the full investigation of the current research situation.Use the self-designed dissolution device as a platform.With typical limestone and white clouds in the study area.The single-variable erosion test was performed on 22 sets of 66 test pieces.At the same time,limestone and dolomite test specimens were placed at 3 sites in Xiao Longbei,Bian Yan and Bei Diping from October 2017 to April 2018 for a period of 6 months of observation and analysis.Measure parameters such as conductivity,p H,and water temperature at the monitoring point every month.The Ca²⁺ and HCO₃^- concentrations in the water were titrated on-site.The main conclusions obtained are as follows:1.Lithology is the primary factor affecting the development of carbonate rocks.Under the same reaction conditions,the amount of limestone dissolved is 1.2 to 2.4 times that of dolomite.The initial reaction rate of limestone is 2 to 3 times that of dolomite,which is far lower than that of limestone.Indicating that dolomite is harder to dissolve than limestone.2.The effect of temperature on the dissolution of carbonate rocks is unidirectional.Both lithology erosions increase with increasing temperature.The study area is characterized by high summer temperatures,low winter temperatures,seasonal development of carbonate rocks.Indicating that as the temperature increased,the difference in corrosion between the two became smaller.For every 10°C increase in temperature,the dissolved amount of dolomite increased by 0.7 mg/g and the limestone increased by 0.55 mg/g.Indicating that dolomite is more affected by temperature than limestone.The p H was negatively correlated with the amount of carbonate rock erosion.Both lithology erosions increased with decreasing p H.The difference in corrosion was increased with decreasing p H value.Indicating that limestone is more affected by p H than dolomite.3.The flow of the solution facilitates the dissolution of carbonate rocks.The amount of dissolved CO₂ in the flowing state is much larger than that in the soaking state,and increases with the increase of the flow rate.At the same time,it was found that the change of hydrodynamic conditions influences the chemical dissolution,and it also affects the speed of physical dissolution and destruction.Therefore,the karst development of the strong groundwater runoff zone in the study area is better.4.The erosion rates of limestone and dolomite in the same lithology water are also quite different.The erosion of limestone in Xiao Longbei and Bei Diping is 2 times that of dolomite,and that of Bian Yan is 4 to 5 times.It means that the dissolution rate of limestone is much larger than that of dolomite in exogenous or karst water.