黄河流域(青海段)氮时空分布特征及其来源解析

青海省作为黄河发源区，其境内干支流水质对整个黄河流域和北方地区具有十分重要的战略意义.为深入了解黄河流域(青海段)氮污染特征，采集黄河干流流域、湟水河流域、大通河流域共30个断面不同水期的水样进行监测，系统分析氮时空分布特征，并采用氮氧稳定同位素技术解析了水体中氮的主要来源.结果表明：(1)该区域水体TN浓度在0.33～13.50 mg/L之间，平均值为3.40 mg/L，表现为湟水河流域>大通河流域>黄河干流流域，各形态氮浓度表现为NO₃^--N>TON>NH₄⁺-N>NO₂^--N.(2)各流域TN浓度最高均为丰水期，但枯水期和平水期各不相同，氮形态分布也不同，说明氮污染来源可能存在差异.(3)相关性分析显示，TN与TON、NO₃^--N具有较好的同源性；SIAR模型分析显示，各污染源对NO₃^--N的贡献率表现为土壤源>凋落物源>...

Temporal and Spatial Distribution Characteristics and Source Analysis of Nitrogen in the Yellow River Basin in Qinghai Province

The water quality of the main and tributaries of the Yellow River in Qinghai Province, the birthplace of the Yellow River, is of great strategic significance to the entire Yellow River Basin and the northern region of China. In order to understand the characteristics of nitrogen pollution in this region, 30 water samples were collected and monitored in the main stream of the Yellow River, Huangshui River and Datong River in the wet season, dry season and normal season. The temporal and spatial distribution characteristics of nitrogen forms were analyzed, and the nitrogen and oxygen isotopes were used to identify the sources of nitrogen pollution. The results showed that: (1) The total nitrogen (TN) concentration in water ranged from 0.33 to 13.50 mg/L, with an average concentration of 3.40 mg/L, which was manifested as Huangshui River Basin > Datong River Basin > main stream of the Yellow River. The order of nitrogen concentration of each form was NO₃?-N>TON>NH₄+-N>NO₂?-N. (2) The highest TN concentration in each basin occurred in the wet period, while the TN concentration in dry season and normal season showed different trend, as well as the distribution of nitrogen forms, indicating that there might be different pollution sources in different water seasons. (3) Correlation analysis showed that TN had good homology with TON and NO₃?-N. The analysis results of SIAR isotope model showed that the contribution ratios of the six sources to NO₃?-N were: soil source > litter source > urban point source > rain source > scattered domestic sewage source> livestock manure source. In wet season, the contribution ratios of soil and litter source in the Huangshui River decreased, while the contribution of urban point source increased. It might be related to the insufficient treatment of urban domestic sewage caused by the mixed flow of rain and sewage in the wet season. The research shows that nitrogen pollution in the Yellow River Basin (Qinghai section) is mainly concentrated in the Huangshui River Basin, and soil source, litter source and urban point source are the dominated sources in this region. It is necessary to focus on improving the sewage pipe network and enhancing the capacity for urban domestic pollution control.