沙河流域非点源溶解态氮负荷模拟及源解析

利用通用流域负荷模型(GWLF)对沙河流域2006—2012年的溶解态氮(DN)负荷进行了定量分析和来源解析,并基于模型分析了各污染源的季节性差异。模型在沙河流域适用性良好,月径流和DN负荷在校准期和验证期的ENS和R2都大于0.6,模型具备可靠的模拟能力。模拟结果表明,沙河流域DN年均负荷以非点源污染为主,占总污染负荷的82.7%。在所有土地利用类型中,耕地的DN负荷贡献率最大(64.5%),表明人类影响下的农业生产活动是流域非点源污染最主要的来源。同时,沙河流域DN负荷污染源组成表现出明显的季节性差异,丰水期地表径流是最主要的污染源(47.0%),而枯水期农村生活污染源(45.0%)和点源(23.1%)贡献相对显著。因此,在制定负荷削减方案时,应考虑氮污染源的季节性。

Simulation and Source Apportionment of Nonpoint Source Dissolved Nitrogen Load in Shahe Watershed

Generalized Watershed Loading Functions (GWLF) was employed to estimate dissolved nitrogen (DN) load and perform source apportionment in Shahe Watershed from 2006 to 2012.The seasonal variation of pollution source was also analyzed based on model results.Satisfactory performance of GWLF was revealed by the ENs and R2 of greater than 0.6 in calibrating and validating streamflow and DN.The result indicated that the nonpoint source pollution had the highest ratio of the annual average DN load,accounting for 81.6％.Among all the land uses,farmlands contributed most to DN load in Shahe watershed,indicating that agricultural activities dominated by human were the major contributor of nonpoint source pollution.Besides,seasonal differences of the contribution ratio from DN pollution source were significant.Runoff was the major pollution source in the wet season;however,septic system and point source were more significant in the dry season.In order to efficiently reduce and control nitrogen pollution in Shahe Watershed,it is neces sary to consider the difference of pollution source constitution between wet season and dry season with respect to the formulation of pollution reduction plan and control measure preference.