气候变化对小流域氮、磷通量的影响——以延安市河流流域为例

Impact of climate change on the variation of nitrogen and phosphorus fluxes at watershed scale:a case study in watersheds of Yan’an City

采用外源污染物负荷模型和流域氮、磷通量核算模型,结合流域土地利用和气象数据,在延安市4条河流流域建立了流域氮、磷负荷经验模型,分析流域氮、磷通量与净人为氮、磷输入量,降水量,土地利用类型等因子之间的响应关系。结果表明:净人为氮、磷输入量,降水量和土地利用类型变化是氮、磷通量变化的主要原因,其中降水量可以分别解释流域氮、磷通量变化的25.67%和18.29%,降水量的增加会显著增加氮、磷通量;利用区域气候模式数据模拟了近期和远期不同发展情景下流域氮、磷通量的变化情况,在气候变化的驱动下,即使净人为氮、磷输入量和土地利用类型保持现状不变,氮、磷通量在远期预测中仍会呈增加趋势,林地面积的增加可以在一定程度上减缓降水对氮、磷通量的影响。气候变化和人类活动均会对流域氮、磷通量产生影响,在制定流域氮、磷削减方案时,需要考虑气候变化对方案效果的影响。

The external pollutant loading model and the nitrogen and phosphorus fluxes model,combining land use pattern and meteorological data,were used to established an empirical model of nitrogen and phosphorus loading in four river watersheds of Yan’an City,for analyzing the response relation of the fluxes of nitrogen and phosphorus on net anthropogenic nitrogen and phosphorus input,precipitation,land use pattern and other factors.According to the results,the net anthropogenic nitrogen and phosphorus input,precipitation and land use pattern were the main causes for the change of the nitrogen and phosphorus fluxes.Precipitation could respectively explain 25.67%and 18.29%of the nitrogen and phosphorus fluxes variation,and the increasing precipitation will significantly increase the nitrogen and phosphorus fluxes.A meteorological dataset from regional climate models was used to simulate the short-term and long-term variation of nitrogen and phosphorus fluxes under different development scenarios,and the results showed that driven by the change of climate,even if the net anthropogenic nitrogen and phosphorus loading and the land use pattern remained unchanged,the future nitrogen and phosphorus fluxes would still increase in the long-term prediction.The increasing of forest land could mitigate a certain extent of the influence of precipitation on nitrogen and phosphorus fluxes.These results indicated that climate change as well as anthropogenic activities could affect the nitrogen and phosphorus fluxes,and the impact of climate change on the effectiveness of nitrogen and phosphorus reduction programs should be considered while formulating the nitrogen and phosphorus reduction programs.