犀牛湖高氟化物成因分析及控制对策研究OA

Aiming at the excessive fluoride pollution in Xiniu Lake,a closed lake located in the arid and semi-arid regions of northern China,targeted governance strategies were proposed in this research after the spatial distribution characteristics,sources and migration pathways of fluoride were analyzed.Historical monitoring data and intensive site sampling covering the lake water,inflow water,soil and sediment were adopted for the research.The results showed that obvious north-south gradient differences in fluoride pollution were detected in Xiniu Lake.Higher fluoride values were measured at sampling sites in the northern lake area rather than the southern area during two sampling campaigns,which were primarily affected by localized dilution triggered by low-fluoride water replenishment from Xida Ditch.The average fluoride pollution across the whole lake was calculated as 1.34 mg/L.The average total fluorine content in surrounding topsoil was determined to be 241.17 mg/kg,lower than the national average value of 436 mg/kg.Nevertheless,a high proportion of water-soluble fluorine(6.15 mg/kg)was recorded,and fluorine content was found to rise with increasing soil depth.The average total fluorine content of sediments was measured at 357.4 mg/kg.Significantly higher fluorine pollution(399～532 mg/kg)were quantified in lake sediments compared with lakeshore sediments(233～356 mg/kg),which indicated continuous fluorine release into water bodies via surface runoff or groundwater recharge.According to source apportionment analysis,impacts from historical industrial sources were verified to have disappeared.Current fluorine enrichment was dominated by endogenous accumulation,and inflow rivers(Xida Ditch and Luhua Ditch)were only capable of short-term dilution.In consideration of the shallow-water feature of Xiniu Lake with an average water depth of 2 m,comprehensive countermeasures centered on water replacement were put forward.Low-fluoride water diverted from Xida Ditch was suggested to replace lake water in batches or continuously.Water volume and replacement cycles were optimized on the basis of dynamic water quality monitoring.Chemical precipitation and ecological restoration were supplemented simultaneously to restrain the resuspension of sediment fluorine.An integrated scheme balancing efficiency,cost-effectiveness and ecological safety was provided for the remediation of high-fluoride lakes in arid zones.