基于输出系数模型的水库汇水区农业面源污染负荷估算

面源污染是导致环境恶化的主要原因之一,由其所引起的水体富营养化现象,已严重威胁着水环境生态安全。该文以长春市水源地新立城水库汇水区为研究对象,选用输出系数模型对其农业非点源污染负荷进行估算,得到结果如下:1)汇水区内农业非点源污染总氮、总磷负荷量分别为2 822.485、471.123 t/a,且二者空间分布较一致;2)总氮负荷量的贡献率大小顺序为:土地利用畜禽养殖农村人口,总磷的污染负荷贡献率大小为:畜禽养殖土地利用农村人口;3)选取水库2004-2013年水质监测数据计算营养盐输出负荷,与模型估算的输出负荷进行对比,得到模型模拟具有较高精度,系数选取合理可靠,可信度高,可在研究区范围内进行推广,能够为长春市水源地综合整治及水利规划提供了数据支撑及科学依据。

Load evaluation of non-point source pollutants from reservoir based on export coefficient modeling

Abstract: Non-point source (NPS) pollution has been recognized as the largest threat to water resources throughout the world, and the evaluation of NPS loads is a priority in recent years. Major pollutants, particularly from agricultural activities, include nitrogen (N), phosphorus (P) and sediment that have been released into aquatic environments. It is also necessary to identify the spatial and temporal distributions of NPS pollutants and the highly polluted areas for the purpose of watershed management. Some models have been widely used at the watershed scale. However, variations in natural and social factors make it difficult to find a proper model to be used on NPS pollution management in China. The export coefficient model (ECM) has been used to evaluate the influence of NPS on total nitrogen (TN) and total phosphorus (TP) in several cases, such as the Xitiaoxi watershed in Zhejiang, the Three Gorges Reservoir Area in Hubei Province, Beijing City, Daqing City, Heilongjiang Province, which all provide important reference for NPS management. Therefore, in this paper, the ECM was used to assess the influence of NPS on N and P loading in the Xinlicheng Reservoir of Jilin Province. Xinlicheng Reservoir, one of the drinking water resource areas in Changchun City, is located in middle of Jilin Province, and its catchment area covers an area of 1970 km2 and includes 1 county, 3 districts and 2 cities. A large percentage of the population in the Xinlicheng Reservoir catchment area lives in small villages. The domestic sewage from the villages is scattered and discharged with little or no treatment. Data related to the main non-point sources were analyzed, including rural domestic wastes, distributed livestock farms, fertilizers and land use. Additionally, the potential N and P loading from NPS originated from a variety of sources were estimated and analyzed, including rural domestic waste, livestock farms, and land use. They gave the temporal distributions of the potential NPS loads within the reservoir area. In this study, the NPS pollutant load was simulated using the ECM. The results demonstrated that the TN and TP loads were respectively 2822.485 and 471.123 t/a. TN and TP loads were affected by the type of land utilization significantly. The contributions to pollution load from various types of pollutant sources were different. The magnitude orders of the contribution from various types of pollutant sources for TN and TP loads were wastewater and garbage from land use > livestock breeding > rural residents, and livestock breeding > land use > rural residents respectively. The differences among various districts about TN and TP loads and their load intensities were great. The research about the distribution of N and P pollutants and their load intensities from agricultural non-point sources can provide a foundation on regional planning and agricultural structure adjustment in study area. Furthermore, these findings demonstrate that the ECM can provide a simple and reliable approach to evaluate the potential N and P loading in the Xinlicheng Reservoir of Jilin Province and is useful for the planning and management of the local agricultural watersheds.