在城市化影响下，城市湖泊污染来源增多且污染物呈多样性特征，解析城市湖泊污染来源及污染特征，对城市湖泊环境治理具有重要意义。本论文将水动力-水质-同位素示踪-多元数理统计-GIS等多种溯源理论和分析方法创新联用，分别从隐蔽排污口筛查、水相硝酸盐同位素溯源、沉积物重金属多元分析三个角度解析以泉水补给为主的典型城市湖泊-大明湖的污染来源，提出适用于大明湖污染溯源的研究技术方法，为水污染防控工作提供指导意见。研究结果如下： （1）针对城市湖泊隐蔽排污口排污特征，提出基于三维水动力和水质浓度GIS空间分布图的城市湖泊隐蔽排污口的筛查技术手段，并在大明湖实际验证了该创新技术的可行性和有效性。通过三维水动力筛查在大明湖共发现六个水动力突变区域，对应的三维（地方空间直角坐标系ENU）流速和流向发生一定程度变化，平均流速显著升高。同时，结合全湖水质的空间变异特征分析确定其中4个区域为隐蔽排污口，它们附近区域水流平均流速与排出污染物浓度一般具有显著相关性。分析过程中还发现湖体仅表层0~0.3 m水深会受到游船和风力的扰动；隐蔽排污口排污，东护城河回流、西护城河汇入和游船活动是导致全湖水质空间分布差异显著的主要原因。 （2）以水相硝酸盐为研究对象，提出联用氮氧同位素 - SIAR模型 - GIS - 数理统计分析开展城市湖泊污染溯源研究手段，可从定性、定量、空间位置、迁移转化等角度解析湖体硝酸盐污染源。本研究将该研究手段应用于大明湖，基于GIS-数理统计分析的营养盐时空变异特征解析指出湖体三季水相中硝酸盐含量均较高，是湖体主要污染物。同时，结合湖体水相硝酸盐氮氧同位素特征发现大明湖水域硝酸盐主要来源于西护城河的粪肥和生活污水，西护城河道隐蔽水下排污口排污是造成粪肥和污水外排的主要污染问题。本研究还利用SIAR模型估算土壤氮，大气沉降，粪便和污水以及NO3-肥料四类主要污染源对大明湖水域中硝酸盐污染贡献比例，结果表明它们贡献量存在季节差异，降雨是导致这种变化的主要因素。 （3）以8种典型的重金属元素（Cu、Pb、Zn、Cd、Cr、As、Ni和Sr）和沉积物粒径作为研究对象，通过多分析方法从多角度辨析大明湖表层沉积物重金属来源。大明湖表层沉积物受外界干扰显著，存在重金属外源污染。主湖区域重金属污染主要来自生活污染源，包括隐蔽水下排污口、西护城河、游船活动，它们使近岸区域沉积环境水动力强度升高且不稳定；东湖重金属污染来自周边人类活动排放的Ni、As。 （4）基于上述溯源解析结果，提出针对性大明湖污染防治技术与工程措施：从污染源控角度：及时封堵湖体现已找到的隐蔽排污口和雨水口；排查西护城河以隐蔽排污口为主的污染源；严格监管湖内游船活动；加大对东湖区域周边Ni、As重金属污染的排查力度。从生态拦截角度，将湖体周边草坪改造为梯级植草沟；对河道采取生物措施（如生物栅）均能改善西护城河水质。从水利调节角度，优化北水门调水量，同时对出水口改造，增设水位计和自动闸，防止东护城河倒流。

With the influence of urbanization, the pollution sources of urban lakes are increasing and the pollutants are diverse. Analysis of urban lake pollution sources and pollution characteristics is of great significance for urban lake environmental management. In this paper, hydrodynamic-water quality-isotope tracing-multivariate mathematical statistics-GIS and other traceability theories and analysis methods were innovatively combined. The pollution sources of Daming Lake with spring replenishment, which is typical urban lake, were analyzed from three perspectives: screening of hidden sewage outlets, traceability of nitrate isotopes in water phase and statistical analysis of heavy metals in sediments. The research method provides guidance for the prevention and control of water pollution. The results were as follows: (1) Aiming at the characteristics of sewage discharge from underwater sewage outfalls of urban lake, a screening technology for underwater sewage outfalls of urban lake based on three-dimensional hydrodynamic and water quality concentration GIS spatial distribution map was proposed, and the feasibility and effectiveness of the innovative technology were verified in Daming Lake. Through three-dimensional hydrodynamic screening, six turbulent regions were found in Daming Lake. The corresponding three-dimensional flow velocity and direction changed and the average flow velocity increased significantly. Combined with the analysis of spatial variation characteristics of water quality in the whole lake, the complicated hydrodynamic in four regions were mainly ascribed to the existence of underwater sewage outfall. And the average flow velocity of water near them was generally significantly correlated with the concentration of pollutants discharged. In addition, it was found that the water depth of the lake is only 0-0.3 m above the surface, which was disturbed by cruise ships and wind forces. Underwater sewage outfalls, return flow of the eastern moat, inflow of the Western moat and cruise ship activities were the main reasons leading to significant differences in spatial distribution of water quality in the whole lake. (2) Taking nitrate as the research object, a method of traceability of urban lake pollution by combining nitrogen and oxygen isotope - SIAR model - GIS -mathematical statistics analysis was proposed. The sourcse of nitrate in lake can be analyzed qualitatively, quantitatively, spatially, migration and transformation. Applying this method to Daming Lake, the research found that the nitrate in the water phase of the lake in three seasons was high, and it was the main pollutant in the lake. Nitrate in Daming Lake mainly came from manure and domestic sewage from the West moat, and sewage discharge from the underwater sewage outfalls of the West moat is the main pollution problem causing manure and sewage discharge. In addition, there were seasonal differences in the contribution ratio of soil nitrogen, atmospheric deposition, feces and sewage, and NO3- fertilizer to nitrate pollution in lake, and rainfall was the main factor leading to change. (3) Eight typical heavy metal elements (Cu, Pb, Zn, Cd, Cr, As, Ni and Sr) and sediment size were taken as the research objects, and the sources of heavy metals in surface sediments of Daming Lake were identified by multi-analysis method. The surface sediments of the lake were obviously disturbed by the outside. The heavy metal pollution in the main lake area mainly comes from the sources of living pollution, including hidden underwater sewage outlets, West moat and cruise ship activities, which made the hydrodynamic intensity of the coastal sedimentary environment increase and unstable. The heavy metal pollution in the East Lake came from the Ni and As discharged from the surrounding human activities. (4) Based on the results of traceability analysis, this paper put forward the corresponding pollution control technology and engineering measures for Daming Lake. From the point of view of pollution source control, the underwater sewage outfalls and rainwater outlets should be sealed up. The pollution sources should be investigated mainly from underwater sewage outfalls in the West moat. The activities of cruise ships should be strictly supervised in the lake. and the investigation of Ni and As heavy metal pollution around the East Lake should be intesified. From the point of view of ecological interception, the lawn around the lake should be transformed into a cascade grass planting ditch, and the water quality of the West Moat can be improved by adopting biological measures such as biological grating. From the point of view of water regulation, water level gauges and automatic gates should be added to prevent the reverse flow of the East moat.