Study On The Source And Remediation Countermeasures Of Fluoride In Coal Mining Subsidence Area Of Riyue Lake In Yongcheng City

Due to the wide range and severe damage of coal mining subsidence areas left over from coal mining in China,the restoration and management of coal mining subsidence areas have always been highly valued by the national government.Fluoride pollution is a prominent problem that urgently needs to be solved in lakes in coal mining subsidence areas,which is closely related to the ecological environment and human health.It is a key link in the ecological restoration of lakes in coal mining subsidence areas.This article takes Riyue Lake in Yongcheng City as the research object,evaluates and analyzes the current situation of fluoride in the lake and the spatiotemporal distribution of concentration.It further explores the hydrochemical characteristics of Riyue Lake and identifies the factors that affect and control fluoride enrichment.By designing and conducting experimental research,model simulation,and other methods,the sources of fluoride in the Riyue Lake are explored,and effective remediation strategies are proposed to provide feasible support for improving the fluoride pollution problem in the water quality of the Riyue Lake.The specific research content and results are as follows:(1)According to the analysis of experimental monitoring results,it can be seen that the fluoride in the water of the Sun Moon Lake has reached the Class V standard.Riyue Lake belongs to a slightly alkaline lake body,with fluoride concentrations ranging from 1.06 to 2.63mg/L.From the perspective of time distribution characteristics,the overall fluoride concentration in the water body shows a trend of dry season(2.22 mg/L)>flat season(2.09mg/L)>high season(1.75 mg/L);From the perspective of spatial distribution,the spatial distribution of fluoride concentration shows a trend of Moon Lake>Sun Lake;By analyzing the geochemical characteristics of fluoride enrichment,it is preliminarily concluded that the accumulation and enrichment of fluoride are controlled by evaporative crystallization and human factors.(2)Design and carry out atmospheric sedimentation fluoride monitoring experiments,double loop water injection soil infiltration experiments,surface runoff soil dissolution experiments,and groundwater fluoride concentration monitoring experiments.Based on the dynamic balance analysis results of daily and monthly lake water volume,it is calculated that during the monitoring period,the replenishment amount of precipitation and runoff in the daily and monthly lake reached 1.55 t/a,the groundwater replenishment amount reached 8.99 t/a,and the total amount of fluoride entering the lake reached 10.76 t/a.(3)Establish a two-dimensional hydrodynamic and water quality model of the Riyue Lake,using the measured data as the initial and boundary conditions,and complete the calibration of the model.Compared with the distribution of fluoride concentration in the current year’s water quality of the lake,by adding water system connectivity measures,it is concluded that the hydrodynamic force in the lake area can be improved before and after the connection of the Sun Moon Lake water system,with an average flow velocity increase of 0.00014 m/s,and an improvement ratio of 15.23%;By adding ecological restoration measures,it is concluded that the fluoride concentration in the lake area has been improved before and after the connection of the Riyue Lake water system.The average fluoride concentration in the Riyue Lake water is1.80 mg/L,with an improvement ratio of 9.0%.The average fluoride concentration in the water around the submerged plant planting area is 1.47 mg/L,with an improvement ratio of 25.7%.