Abstract:

The genesis of the high-fluorien water in Yangshapao reservoir was studied on the basis of investigation and analysis of the surrounding geological condition, hydrogeological condition and the characteristics of soil and fluorine as well as the simulating experimental results for Yangshapao reservoir. The results showed that the formation of the high-fluorine area in Yangshapao reservoir is the results of long-term evolution of the surface environment. The magmatic rocks in the Daxing’anling mountain and unconsolidated deposits in Songnen low plain provide abundant fluorine-rich matter. The river and groundwater provides dynamic condition for fluorine transportation. The typical low-lying topology becomes the geographic condition for high-fluorine formation. The dry and semi-dry climatic condition is the promotion condition for the high-fluorine environment. The fluorine in Yanshapao reservoir mainly comes from the runoff of Erlongtao river, which brings about 99% of the total fluorine annually into the reservoir. The fluorine from the surrounding runoff is 0.014%-0.28% annually. The fluorine from the rainout is 0.012%. The evaporation-concentration process can increase the concentration of fluorine in water. The release of fluorine from the bottom mud is one cause of the increase of fluorine concentration in Yangshapao reservoir, which will have some impacts on the water quality of the reservoir after the Water diversion project from Nenjiang river to Baicheng city brings into practice. It will take about 5 years for the fluorine concentration of the water body in the reservoir decreasing below 1.0 mg/L under conditions of annual water diversion. Otherwise, the strong wind and human activities also have impacts on the fluorine in Yangshapao reservoir.

Key words: Yangshapao reservoir, high-fluorine water, high-fluorine genesis, environmental impact, evaporation and concentration process