泾河流域陕西段水环境容量估算和分配模型研究

Study on Estimation and Allocation of Water Environmental Capacity in Jinghe River,Shaanxi Province,China

非点源污染河流的水环境容量研究对其污染物总量控制具有现实意义。采用输出系数法计算年投放量和年入河量,对年入河量进行按月分配,通过河流输入—输出平衡关系计算研究河段的月自净水量。结果表明:按照水环境功能区划中Ⅲ类水质的要求,泾河流域陕西段总氮全年超标,流域内各污染源的总氮投放量均需削减,削减总量达到3 191.891 1t;按照污染源削减量分配结果,土地利用类型是总氮污染削减量最大的(1 294.239 6t),而畜禽养殖是削减比例最大的污染源(47.76%)。从污染源的时间分配来看,降水量大的丰水期是污染物削减量最大的时期,各污染源的削减量随着降水径流的增大而增大,说明降水径流是造成泾河流域陕西段总氮污染的限制性因子。

The research on river water environmental capacity has practical significance for its pollutant total control in river which is non-point source pollution.Based on the investigation of the application and emission of total nitrogen(TN)for non-point river catchment′s area,the quantities of TN entering the river were computed by means of export coefficient model in Jinghe River.Self-purification capacities of TN in the reach were also estimated in terms of input-output balance.According to the water environmentⅢ water quality target,TN exceeds the standard all year round,and all pollution sources reduction of TN amounted to 3 191.891 1tons.According to the analysis result,the land use type is the largest amount of total nitrogen pollution reduction(1 294.239 6t),and livestock farming is the largest sources of pollution cut proportion(47.76%).From the time distribution of pollution sources,wet reason is the right time of pollution reduction,and pollutant reduction amount of each pollution source enlarges with the increase of runoff.Rainfall runoff is the restrictive factor of total nitrogen pollution in Jinghe River,Shaanxi Province.