摘要：The dynamic changes of nitrogen (N) loads have been significantly impacted by the rapid expansion of many cities, potentially escalating the risk of N pollution in cities. However, the spatiotemporal changes of N loads in source and sink landscapes remain unclear in urbanization. In this research, we used source–sink landscape theory to identify the source–sink landscape in the process of N flow at the city scale and investigated the spatiotemporal changes of N loads in the source–sink landscape from 2005 to 2015 in Xiamen, a rapidly urbanizing city in southern China. The total N loads of source landscapes increased by 2 times between 2005 and 2015, with an average annual growth of 26%, while the total N loads of sink landscapes climbed gradually, with an average annual increase of 8%, according to our findings. Moreover, in terms of the spatial gradient, the N loads of the source landscape fluctuated downward and reached their peak in the urban center, whereas the N loads of the sink landscape tended to rise and reached their peak outside of the city. Our findings offered a fresh viewpoint on the source–sink landscape in N flows at the city scale and offered useful guidance for N spatial management to support sustainable city development.
