摘要
西南三江流域作为我国西南地区重要的生态屏障和水资源战略储备区,研究其氮磷排放的时空分异特征对流域水资源保护具有重要意义。本文基于ArcSWAT水文模型,将西南三江流域划分成40个子流域,并按水文和地貌特征进一步划分为上、中、下游;同时针对该流域地形起伏大、降雨集中、土壤侵蚀严重等自然特征,在传统输出系数模型基础上引入降雨侵蚀力因子、土壤侵蚀因子、地形因子和植被因子,结合产排污系数法系统估算了2000年、2010年和2021年西南三江流域TN、TP的排放量,并借助GIS分析不同子流域氮磷排放的时空分异特征及其源结构演变。结果表明:①西南三江流域的TN和TP排放量在2010年达到峰值,分别为17.83×10^(4)和0.76×10^(4) t,且面源排放在2010−2021年间有所减少但仍占主导地位。②TN和TP的排放量在空间上呈现“上游低、下游高”的分布格局,下游的24~40号子流域贡献了全流域67%的TN和81%的TP排放量。③面源排放方面,TN主要来自化肥施用、土地利用和大气沉降,TP主要来自化肥施用、农村畜禽散养和土地利用;点源排放方面,TN和TP的主要来源均为规模化养殖、城镇生活和农村生活。研究显示,自然因素对西南三江流域的氮磷迁移扩散具有关键调控作用,该流域氮磷排放在时空上具有显著异质性,且排放源结构呈多元化趋势。该研究从子流域尺度揭示了西南三江流域氮磷排放的时空异质性和源结构,可为区域氮磷分区精准治理提供科学依据。
Understanding the spatiotemporal variability and source structure of total nitrogen(TN)and total phosphorus(TP)losses in the Three Rivers Basin of southwest China is essential for effective watershed nutrient management and water resource protection.In this study,the ArcSWAT hydrological model was used to divide the Three Rivers Basin into 40 sub-basins,which were further categorized into upstream,midstream,and downstream regions based on hydrological and geomorphic characteristics.Given the region′s steep terrain,concentrated rainfall,and severe soil erosion,an improved export coefficient model incorporating rainfall erosivity,soil erodibility,topographic factor,and vegetation cover was developed.Combined with pollutant discharge coefficients,TN and TP losses in 2000,2010,and 2021 were estimated,and their spatiotemporal patterns and source contributions were analyzed.The results show that:(1)TN and TP losses in the Three Rivers Basin peaked in 2010 at 178,300 t and 7,600 t,respectively,and although non-point source pollution decreased between 2010 and 2021,it remained the dominant source.(2)TN and TP losses exhibited a clear spatial gradient,increasing from upstream to downstream.Sub-basins 24-40 contributed 67%of TN and 81%of TP in the Three Rivers Basin.(3)TN mainly originated from fertilizer application,land use,and atmospheric deposition,whereas TP losses were primarily driven by fertilizer use,animal manure,and land use.For point sources,both TN and TP were largely associated with intensive livestock production,urban domestic discharge,and rural household wastewater.Overall,the findings indicate that natural factors play a key regulatory role in the migration and dispersion of nitrogen and phosphorus in the Three Rivers Basin,and that TN and TP losses in the basin exhibit significant spatiotemporal heterogeneity and increasingly diverse source structures.This study provides a scientific foundation for developing targeted,sub-basinscale nutrient pollution control strategies in the region.
作者
王飞达
李晓琳
胡丹
李佳璇
高俊淑
WANG Feida;LI Xiaolin;HU Dan;LI Jiaxuan;GAO Junshu(College of Soil and Water Conservation,Southwest Forestry University,Kunming 650224,China;China Academy of Urban Construction,Kunming 650051,China)
出处
《环境科学研究》
北大核心
2026年第2期323-335,共13页
Research of Environmental Sciences
基金
云南省应用基础研究计划项目(No.202201AT070051)
云南省水土保持与荒漠化防治学一流学科资助项目(No.SBK20240023)。
关键词
西南三江流域
总氮(TN)
总磷(TP)
输出系数模型
产排污系数法
the Three Rivers Basin of Southwest China
total nitrogen(TN)
total phosphorus(TP)
export coefficient model
discharge coefficient method
