Experimental Studies Of Lake Sediments Fluoride Release Laws And Mechanism In Western Jilin Province

This paper, based on technology development projects in Jilin Province - Jilin Province, the western lakes sediment fluoride fluoride release mechanism of long-term study, carried out and launched a special study. The western region of Jilin is located in the southwestern tip of the Songnen Plain, the eastern part of Horqin grassland, lakes region-intensive, but the prevalence of bad water quality, the alkaline, high-fluorine water, so the lake sediments of the western Jilin fluoride release of the laws and the mechanism has far-reaching significance to improve the water quality and the ecological environment.In the paper, Chagan Lake, Dabusupao lake, Huaaopao lake , yueliangpao lake, xianghai lake and daozipao lake are focused on lakes. Lakes, the main problem with the water quality of lakes in general are bad, especially the F-over serious, the highest fluoride content in the sediment, the sediment to improve water quality in the area of the fluorine has become the focus of the study.In order to analyze the western region of Jilin fluoride lake sediments transporttion and change mechanism, the paper researchs by field investigation and laboratory. Analyzing of most of the water quality of lakes,they are Cl-Na type, HCO₃-Na.Ca type, Cl.CO₃-Na type, HCO₃.CO₃-Na and HCO₃-Na type water; the chemical composition of sediments, by the anion component, CO₃^2-, HCO^3-, SO₄^2- are the most; cationic component, mainly by Ca²⁺. Full fluoride Lake sediments in West Jilin Province is 136～603 mg/kg. High pH values and high TDS is the most obvious feature of the water quality in the region.Studied lake sediments in West Jilin Province fluoride release process: fresh sediments extend sediment release, the cumulative fluoride increases gradually, at 4 days the largest cumulative emissions are becoming more and more post-release stability; the process is affected by the physical and chemical character of sediments, such as particles, other chemical matter and so on. In addition, the sediment overlying water concentration and the overlying water body contact area are also one of mainly factors about fluoride release,and the relations are obvious. Fluoride release will increase,if the 2 factors increase. That indicates that the full fluoride and sediment-soluble fluoride salt are the main factors and material basis in a cumulative release of fluoride.Through the fresh sediment fluoride adsorption experiments show that the lake sediments is the main substance which adsorps fluoride in lake. In the Experiment Adsorption Volume is 13.12 16.25mg/L, mainly differences in sediment is from particle size, full Fluoride and fluoride concentration difference Overlying water concentration.By lakes sediment of the western Jilin pore water experiments, analyzeing the sediment release of fluoride, show that fluoride release of sediment have two processes, firstly, the early experiments the process is led by the water molecular diffusion process, and by the end of the mid-and late adsorption by soil surface dominated by the release of fluoride. In addition, sediment pore small gap in the Adsorption of fluoride ion in the solid particles keep firmly fluoride in the water gathering space, resulting in the interstitial water fluoride content higher than the fluorine content in the overlying water.Overlying water fluoride concentration and pH value of sediment was positively significantly correlated, indicates that pH value of lake sediments on the western Jilin fluorine migration and release play an important role. The main reason may be:â‘ desorption of fluoride reaction: First, the impact of pH value of the charged ions, thereby affecting the surface of the solid-phase affinity; followed by a high pH will also affect the nature of the surface of solid phase, thus affecting the surface of solid-phase ion affinity and adsorption capacity; the third, pH value is conducive to higher adsorption of metal cations to promote the desorption of anions;â‘¡A lot of water and soil environment of OH- and Ca²⁺, Fe³⁺, Mg²⁺ and other ions generate precipitation, that decreases cationic and all opportunity fluoride, so that a large number of fluoride release in aqueous solution.â‘¢alkaline conditions, a large number of OH-and clay minerals, humus and soil colloid by adsorption of the fluoride exchange, so that fluoride migration into the water. In addition to join a large number of OH-after, due to OH^- and F- radius similar to the lattice of clay minerals in the soil of the F- replacement out. Therefore alkaline environment is conducive to release of fluoride.Researching the relationship among ion in Lakes of the western Jilin Province, shows that [K⁺ + Na⁺],[HCO₃^-], [CO₃^2-] and [Cl^-] and pH value and [F^-] are significantly correlated. Although the western Jilin lakes pH value and [F^-] is an indirect, the element fluorine migration plays an the most important role in the fluoride release. Research results provide a scientific theoretical basis for the lake water quality monitoring.sediment full fluoride, calcium, sediment particle size and pH value is the most important factors about Sediment fluoride release sediment particle size is propitious to fluoride accumulation, Ca²⁺ and Mg²⁺ are very difficult to bind with F^-. Western Jilin sediment fluorine transporttion and change into the lake mainly get across precipitation-dissolution, adsorption- desorption and the pH value of the role. [K⁺ + Na⁺],[HCO₃^-],[CO₃^2-] and [Cl^-]etc control the overlying water fluoride concentration. the adsorption– desorption is limited because of The physical and chemical properties of Lake sediments; alkaline soil and water environment increases the affinity of Solid-phase surface to promote the adsorption of cationic and strengthen the exchange capacity and ability. Therefore, from water and soil environment of sediment to the water fluoride from water and soil environment, transporttion and change has become the main direction of fluoride.