区域尺度黄河流域面源污染负荷特征与来源解析

CHARACTERISTICS AND SOURCE ANALYSIS OF NON-POINT SOURCE POLLUTION LOAD IN THE YELLOW RIVER BASIN ON A REGIONAL SCALE

掌握黄河流域甘肃段面源污染负荷特征及其来源,是在区域尺度上提升水环境污染治理水平的重要基础。基于DPeRS面源模型,从农田径流、城镇径流、畜禽养殖、农村生活、水土流失5大污染类型,选取TN、TP、NH_(3)-N和COD 4个污染指标,对甘肃黄河流域9个市(州)58个县(区)面源污染进行污染负荷估算、污染来源解析及空间分布分析。结果表明:从模型估算结果看,2018年整个流域TN、TP、NH_(3)-N和COD面源污染排放负荷均值分别为65.6,11.8,19.1,77.2 kg/km^(2)。从区域尺度分析,甘肃黄河流域TN、TP面源污染负荷最高的区域均是兰州市安宁区,分别占整个流域总负荷的10.83%和5.16%;NH_(3)-N和COD面源污染负荷最高的区域均是临夏回族自治州临夏市,分别占整个流域总负荷的26.23%和56.56%。从污染产生来源分析,TN、TP、NH_(3)-N和COD的首要污染来源分别为农田径流、水土流失、农田径流和畜禽养殖。从空间分布分析,黄河流域各县(区)面源污染总负荷呈中间高两边低的分布特征,污染负荷较重的区域主要集中在黄河兰州段、大夏河临夏段、渭河天水段等局部区域。

Grasping the characteristics and sources of non-point source pollution load in the Gansu section of the Yellow River Basin is an important basis for improving the level of water pollution control on a regional scale.Based on the DPeRS model,this study selected four pollution indicators of total nitrogen,total phosphorus,ammonia nitrogen and chemical oxygen demand,from the five major pollution types,farmland runoff,urban runoff,livestock and poultry breeding,rural life,and soil erosion.Pollution load estimation,pollution source analysis and spatial distribution analysis were carried out on non-point source pollution of nine cities(prefectures)and 58 districts(counties).The results showed that:from the model estimation results,the average non-point source pollution load of total nitrogen,total phosphorus,ammonia nitrogen and chemical oxygen demand in the entire basin in 2018 was 65.6,11.8,19.1,77.2 kg/km^(2).From the regional scale analysis,the area with the highest non-point source pollution load of total nitrogen and total phosphorus in the Yellow River Basin of Gansu was Anning District,Lanzhou,which accounted for 10.83%and 5.16%of the total load of the entire basin respectively;the area with the highest non-point source pollution load of ammonia nitrogen and chemical oxygen demand was Linxia City in Linxia Prefecture,respectively,accounted for 26.23%and 56.56%of the total load of the entire basin.From the analysis of pollution sources,the primary pollution sources of total nitrogen,total phosphorus,ammonia nitrogen and chemical oxygen demand were farmland runoff,soil erosion,farmland runoff,and livestock and poultry farming.From the spatial distribution analysis,the total non-point source pollution load of each district(county)of the Yellow River Basin presented a distribution characteristic of middle-high and low sides.The areas with heavier pollution load were mainly concentrated in local areas such as the Lanzhou section of the Yellow River,the Linxia section of the Daxia River,and the Tianshui section of the Weihe River.