关键词: 氮磷排放; 时空差异; ArcGIS; SWAT模型; 漓江流域; 会仙湿地;

Abstract: Serious agricultural surface source pollution exists in the Huixian wetland in the Qingshitan irrigation area of the Lijiang River basin.Field monitoring experiments of nitrogen and phosphorus discharge were conducted in the main water systems of the wetland, the Xiangsi River, the Huixian River, the Mudong River and the ancient Guiliu Canal, to study the spatial and temporal differences of nitrogen and phosphorus discharge in the Huixian wetland and to provide reference for surface source pollution prevention and control and management.Using ArcGIS software and the SWAT model, the study area was divided into sub-basins and 15 monitoring points were deployed.The spatial and temporal significant differences in nitrogen and phosphorus discharge loads and concentrations in the area were analyzed by using the repeated measures ANOVA method of SPSS software.The results showed that total nitrogen(TN)was less affected by spatial and temporal factors, and there was no significant difference in emission loads and concentrations.The total phosphorus(TP)and ammonia nitrogen(NH3-N)emission loads at different monitoring points in the Mudong River section were significantly different due to land use type.The total phosphorus emission loads in the upstream and middle reaches of the Xiangsi River during the irrigation period were significantly different due to industrial wastewater, farming effluent and domestic sewage.The ammonia nitrogen in the middle reaches and downstream of the ancient Guiliu Canal during the non-irrigation period were significantly different.

Key words: nitrogen and phosphorus discharge; spatial and temporal differences; ArcGIS; SWAT model; Lijiang River basin; Huixian wetland;