基于控制单元划分的大辽河流域污染物空间分布及来源解析

为明确大辽河流域污染物特征及污染物来源，建立“流域—控制单元—行政区”空间拓扑关系，对2019年大辽河流域国控断面水质情况、各控制单元内污染物入河量及空间分布特征进行分析。结果表明：1）大辽河流域28个水质监测断面中，逐月水质均能达到《水污染防治行动计划》中考核目标的占29%，超标污染物以COD、NH₃-N为主，超标断面中，COD、NH₃-N主要来源为城镇生活源、农村生活源和分散式畜禽养殖，TP主要来源于不同土地利用类型污染源和城镇生活源；2）2019年COD、NH₃-N、TN、TP污染物入河量分别为59 195.5、3 115.5、18 229.7、538.3 t/a，从污染源贡献上看，总体呈现为城镇生活源>农村生活源>分散式畜禽养殖污染源>不同土地利用类型（含林地、草地、耕地、城镇用地）污染源>工业源>规模化畜禽养殖污染源；3）污染物入河量空间分布均呈现中部>西南部>东北部，其中控制单元C3、C6、C8、C11、C13、C15、C17是重点管控单元，以上重点管控单元中，COD、NH₃-N、TN、TP污染物入河量贡献率分别为68%、73%、77%、72%；4）污染物入河量估算结果与通量模拟值之间误差均小于20%，可用于研究区范围内污染负荷估算。

Spatial distribution and source analysis of pollutants in Daliao River Basin based on control unit division

In order to better understand the characteristics and sources of pollutants in Daliao River Basin, the spatial topological relationship of "Watershed-Control unit-Administrative district" was established, the water quality of the state-controlled sections of Daliao River Basin, the amount of pollutants into the river in every control unit, and the spatial distribution characteristics in 2019 were analyzed. The results indicated that: 1) Among 28 water quality monitoring sections in Daliao River Basin, 29% of the monthly water quality could reach the targets of the Action Plan for Prevention and Control of Water Pollution. COD and NH3-N were the main pollutants that exceeded the standard. In the section exceeding the standard, the main sources of COD and NH3-N were urban life sources, rural life sources and decentralized livestock and poultry breeding, while TP mainly came from pollution sources of different land use types and urban life sources. 2) The amount of COD, NH3-N, TN, and TP pollutants into the river was 59 195.5, 3115.5, 18 229.7, and 538.3 t/a, respectively. The contribution rate in descending order was urban living source, rural living source, decentralized livestock and poultry breeding source, source of various landuse types (including woodland, grassland, farmland, urban land), industrial source, large-scale livestock and poultry breeding source. 3) The spatial distribution of the inflowing amount of pollutants into the river in descending order was central, southwest, and northeast, with C3, C6, C8, C11, C13, C15, C17 being the key control units. In the above key control units, the contribution rates of COD, NH3-N, TN, and TP into the river were 68%, 73%, 77%, and 72%, respectively. 4) The error between the estimation result of the inflowing amount of pollutant into the river and the flux simulation value were all less than 20%. The methods should be suitable for the estimation of pollution load in the study area.