Research progress in source-sink landscape pattern analysis based on non-point source pollution processes in watersheds

Source-sink landscape theory is recommended as an effective way to couple landscape pattern and non-point source pollution processes. A reasonable source-sink landscape pattern layout aids in minimizing nonpoint source pollution risk by lowering non-point source pollution production. In this study, based on previous research results and literature reviews, advances in source-sink landscape pattern analysis based on non-point source pollution processes were systematically reviewed from three perspectives, including distinction of source-sink landscapes, quantization of source-sink landscape patterns, and the indication of source-sink landscapes to non-point source pollutants. To investigate the source-sink landscape based on non-point source pollution, the current research primarily maintains the sense of traditional landscape patterns, and it is necessary to consider spatial coupling relationships and comprehensive functions of multiple elements in order to better distinguish the source-sink landscape ownership in non-point source pollution processes. For analysis of source-sink landscape patterns, the classical location-weighted landscape contrast index is only suitable for watersheds or regions with similar environmental backgrounds. Therefore, it is necessary to consider quantifying more landscape factors to construct or improve the source and sink landscape pattern indices more comprehensively and then optimize the source-sink landscape pattern configuration and reduce risks to watershed landscape ecological security. Finally, the main non-point source pollutants in this study of source-sink landscape patterns were mainly traditional non-point source pollutants such as nitrogen and phosphorus. Therefore, it is necessary to expand source-sink landscape pattern analysis to indicate more non-point source pollutants in order to provide reference benchmarks for future research to better reflect coupling relationship between watershed landscape patterns and non-point source pollution processes.