Study On The Mechanism Of Nitrogen And Phosphorus Pollution Of Reservoir In Sand Source Areas Based On Water-Sediment-Dust Three Interfaces

At present, the lakes and reservoirs of water has been polluted with different degree of point and non-point pollution in our country, and the problem of water eutrophication is becoming more and more serious, nitrogen and phosphorus is the main element causing eutrophication problem. The quite mature research has been done about the mechanism of reservoir pollution of nitrogen and phosphorus from runoff and sediment release diffusion Research also has seen the fruits of atmospheric deposition effect on reservoir pollution. For the reservoir and lake distributed in the cold and arid region, sediment source area, there has the typical characteristics of multiple internal and external pollution sources of synergy including river runoff, the release of sand and sediment dust etc. other than the pollution characteristics of general reservoir. Water and sediment, sediment and sand together as an important carrier of pollution source that affects the cold and arid region, sand source area of reservoir and lake eutrophication process. Previous domestic scholars have not yet studied that nitrogen and phosphorus pollution in the reservoir on the above three kinds of internal and external pollution sources under synergistic effect. The existing achievement is difficult to accurately reveal the pollution mechanism in cold and arid region, sand source area of water, can not accurately predict the migration and transformation of pollutants. Based on the above information, this study has focused on the Dahekou reservoir that is located in Jingmeng sand source regions, obtained experimental data through outdoor monitoring and indoor orthogonal simulation test. In this study, the software technology for ArcGIS and SPSS is used as the supplemented method. And variable fuzzy mathematical method, the multiple linear regression method are used to study the Dahekou reservoir pollution mechanism which is based on the three-phase interface water-sediment-dust. This study provides a new idea and the theoretical basis for the purposeful control of reservoir eutrophication in cold and arid regions, sand area.(1) This study combines the principle of geostatistics and geographic information system, and applies to statistics module of ArcGIS software for the nutrients of four seasons in Dahekou reservoir to do the spatial and temporal variation characteristics of analysis. The nutrients include ammonia nitrogen, nitrate nitrogen, total nitrogen, total phosphorus, CODcr, chlorophyll a total of six measures. The results show that The water quality of Dahekou reservoir in spring concentration contour to show a trend of library center to the surrounding waters, the waters of concentration decreased significantly, and the temporal and spatial variability of summer, autumn, winter festival contour with the direction of current flow is basically the same, by the Luanhe and Tuligenhe inflow waters to export waters direction reduced gradually.(2) In the collection and analysis of the base of a large number of measured water quality data, this study determine the weight respectively by the entropy method, equal weight method, simple thresholding, subjective and objective weighting method. And in this study, variable fuzzy mathematics method was used to evaluate the eutrophication of reservoir water quality. The evaluation result shows that the water quality of the reservoir has reached to the extent of eutrophication,and the waters of the entrance section already to a heavy eutrophication degree. This study reflects the interval feature evaluation levels, and the evaluation results more intuitive.(3) According to the simulation experiment of sediment release, this study analyzes the influence mechanism of environmental factor changes in temperature, pH, water power, dissolved oxygen on release intensity of nitrogen and phosphorus nutrient salt. Taking SPSS 19.0 software as a means of realization, and using a variety of curve type on nitrogen and phosphorus release intensity and temperature, pH, water power and dissolved oxygen to fit in this study. Through comparison, the relationship between the release of nitrogen, phosphorus intensity and temperature, pH, water power environment variables get the best fitness when fits with conic function, and get the lesser fitness when fits with cubic function. However, the cubic function is the best when it comes to dissolved oxygen, with the conic function shows the lesser fitness. The fitting function between the strength of nitrogen and phosphorus release from sediments and the environment variable pH was parabola with upward opening.(4) Through the indoor orthogonal test on nitrogen, phosphorus release from the sediments, the regression equation mathematical model are respectively established between the nitrogen, phosphorus release intensity from the sediments and the environmental variables including temperature, pH, dissolved oxygen. The tests show that, temperature, pH, dissolved oxygen, water dynamic conditions have a significant impact on sediment release of nitrogen and phosphorus.(5) TN, TP load into the reservoir from river runoff, atmospheric dust, sediment release was estimated and the impact mechanism on the reservoir water quality by this way was analysis. The research shows that Dahekou reservoir annual river runoff, sediment release, atmospheric dust contribution rate to reservoir TN load is 63.14%, 24.29%,12.57% respectively. TP load contribute rate is 59.51%.30.41%,10.08% respectively.Though the river runoff is the main input pathway of reservoir nitrogen and phosphorus nutrient, the input of atmospheric dust of nitrogen and phosphorus has played a vital role to the growth of spring algae in reservoir, and that is the indirect cause of the heavy eutrophication in reservoir in Summer and Autumn.