[Spatial and Temporal Characteristics of Nitrogen Non-point Source Pollution in Beijing-Tianjin-Hebei Region Based on PLUS and InVEST Models].

With the rapid development of the economy and rapid population growth, the destruction of the environment by humans is growing, and the discharge of various pollutants has seriously threatened the regional ecological security. First, based on the 2010 Beijing-Tianjin-Hebei land use data, the PLUS model was used to simulate the 2020 land use data and the accuracy of the simulation results was verified with the real data. The land use data of 2030-2050 under the sustainable development scenario （SSP119）, natural development scenario （SSP245）, and economic development scenario （SSP585） were simulated. Then, based on the InVEST model, the spatio-temporal changes of nitrogen pollution in the Beijing-Tianjin-Hebei Region from 2000 to 2020 and in the future under the SSP119, SSP245, and SSP585 scenarios from 2030 to 2050 were estimated. The results showed that the total nitrogen loads in the Beijing-Tianjin-Hebei Region were 41 300, 41 000, and 40 900 tons in 2000, 2010, and 2020, respectively and the total nitrogen load in the Beijing-Tianjin-Hebei Region showed a decreasing trend from 2000 to 2020. Compared with that in 2020, the total nitrogen load in the Beijing-Tianjin-Hebei Region in 2050 under the SSP119 scenario increased by 2 000 tons, the total nitrogen load in the Beijing-Tianjin-Hebei Region in 2050 under the SSP245 scenario increased by 3 200 tons, and the total nitrogen load in the Beijing-Tianjin-Hebei Region in 2050 under the SSP585 scenario decreased by 300 tons. Compared with the SSP245 and SSP119 scenarios, the development of SSP585 was more conducive to the reduction of nitrogen pollution in the Beijing-Tianjin-Hebei Region.