Abstract
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.
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