| Shifosi reservoir was the only control project on the main stream of Liao River and the typical flood detention plain reservoir.The Huangjia water source of the seventh water plant of Shenyang water group and water source of Shenyang agricultural high-tech development zone were distributed within the reservoir,the surface water-groundwater joint regulation and storage was utilized to supply water,the water supply quantity was 100 thousand m3/d.The high nitrogen pollution of Liao River resulted in the nitrogen content increase of test groundwater,and it effected the iron and manganese removal efficiency of the above two water treatment plants and constituted a danger on water supply safety.Therefore,how to prevent and control nitrogen pollution of surface water-groundwater joint regulation and storage system and improve the water treatment efficiency had already attracted attention from the authorities,and it also became the urgent problem to solve.In this study,characteristics of bottom solum in surface water-groundwater transformation system was discussed and the tests on migration and transformation law of ammonia nitrogen was conducted.The nitrogen pollution control research of surface water-groundwater joint regulation and storage water supply source was carried out to provide effective control and protective measures for the safety of urban water supply.The following several aspects of research were basically completed:1.Study on the hydrogeological characteristics analysis of Shifosi reservoir.The hydrology,meteorology and hydrogeology condition of reservoir was mainly investigated.The conceptual model of surface water-groundwater joint regulation and storage was established,provided scientific basis for establishing mathematic model of surface water-groundwater joint regulation and storage.2.The present situation evaluation on the quality of water environment in Shifosi reservoir.The improved comprehensive identification index method which combined analytic hierarchy and entropy weight was utilized to evaluated the reservoir surface water quality.The evaluation results showed that the overall surface water of Shifosi reservoir was V class,water quality of wet season was a bit better than that of dry season,the index of ammonia nitrogen,total nitrogen and BOD exceeded the standard badly.The fuzzy comprehensive evaluation was utilized to evaluate the quality of reservoir groundwater.The evaluation results showed that groundwater quality of dry season was ? and ? class and groundwater quality of wet season was generally?,?class,the main excess factors were iron and manganese.3.The characteristic study of bottom solum in reservoir.The soil samples were collected on the spot to conduce soil test,dissolve test and microbial flora diversity test.The relevant features of bottom solum in reservoir was analyzed.The laser particle distribution measurement method,gravity method and indoor penetration test were used to determined the particle composition,density,porosity and permeability of the bottom solum in reservoir.The results showed that the lithology of reservoir solum was silty sand and it belonged to the weak permeable layer,the thickness was 3.0?4.5m,permeability coefficient is about 5.58×10-2 m/s-6.67×10-2 m/s.The results of indoor dissolve test showed that pollution release of the bottom solum in reservoir included three phases:the quick release,release adjustment and stable release,dissolved oxygen and organic matter content also had certain influence to the release of pollutants in bottom solum of reservoir.The concentration of ammonia nitrogen was about 1.2mg/L?1.6mg/L when the release was stable,the concentration of nitrate nitrogen was 0.8mg/L?1.1 mg/L,the concentration of total iron was0.2mg/L?0.3mg/L,the concentration of total manganese was 0.2mg/L?0.25mg/L.It is indicated that there is a certain effect on the surface water quality in the reservoir area,which is used as the two pollution sources in the reservoir area.The analysis of the microbial flora diversity in bottom solum of reservoir was conducted mainly by the methods of molecular ecology such as DNA extraction,PCR amplification and DGGE.The soil samples of three sections were tested,the results showed that the microbial community at bottom solum of reservoir had diversity and it was associated with pollution level,the microbial diversity of the middle part and exit section sample spots were higher than the entrance section,the dominant bacteria was proteobacteria.4.Study on migration and transformation law of ammonia nitrogen at the bottom solum of reservoir.At first,the systemic clustering approach was applied on the test results of reservoir groundwater quality and it was determined that iron and manganese were most relevant with ammonia nitrogen transformation.And the soil column test of ammonia nitrogen transformation was conducted on dry and wet season,the results showed that three phases which contained diffusion,adsorption and biological oxidation were existed when ammonia nitrogen,iron,manganese ions of surface water passed through the bottom solum of reservoir,the removal of iron was prior to ammonia nitrogen and manganese.The removal of ammonia nitrogen and iron were mainly concentrated in the solum depth of 0-40cm,and the removal of total manganese was mainly concentrated in the solum depth of 25-45cm.The max removal rate of ammonia nitrogen,iron,manganese were 81.25%,89.24%and 80.15%,respectively.As the ammonia nitrogen of reservoir water seriously exceeded the standard perennially.As the existence of superiority strains of ammonia nitrogen transformation in some parts,ammonia nitrogen transformation and the removal of total iron tended to be synchronized.5.Study on the safety precautions of joint regulation and storage water supply system of surface water and ground water.Firstly,the coupling model of surface water-groundwater joint regulation and storage was established and the related parameters in the model were revised by forward fitting indirect method,Visual Modflow was utilized to simulated predict the pollution impact of reservoir groundwater under two conditions of which the existing water wells and future strategic reserved water were continuously running,the results showed the operation of the existing water sources and the strategic reserve water source can cause the groundwater environment in the reservoir area to some extent.Water supply security measures was proposed such as the nitrogen pollution protection system of Shifosi water source which united the prevention and control of water quality,reservoir ecology and joint regulation and storage system in fountainhead of Liao River.A scientific basis for the sercurity protection of surface water-groundwater joint regulation and storage water source was provided in Shifosi reservoir.In this study,soil column test and analysis of microbial strains community diversity was conducted to systematically investigate the space-time evolution regularity of ammonia nitrogen and the influence of iron and manganese distribution which were based on the surface water-groundwater joint regulation and storage water supply system in Shifosi plain reservoir,it expanded the ammonia nitrogen transformation mechanism in the surface water-groundwater joint regulation and storage system,it was also the innovation of this study. |
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