Tracing soil erosion processes in Karst regions using rare earth elements: The role of bedrock outcrops and seasonal impacts

In Karst regions, the impact of widespread bedrock outcrops on soil erosion processes is crucial and cannot be overlooked. These bedrock outcrops not only change the flow of surface runoff, but also have a significant influence on rainfall and sediment redistribution processes driven by runoff. This study aims to utilize simulation experiments and rare earth elements (REE) tracer technology to uncover the underlying effects of exposed bedrock outcrops on the soil erosion process, and the sediment transport patterns on slopes in karst regions during both dry and rainy seasons. The results demonstrate that the REE tracer technique holds considerable practical value for studying soil erosion processes on karst bedrock outcrop slopes. Seasonal variations in soil erosion rates are evident, with distinct differences between dry and rainy seasons due to rainfall flushing effects. Sediment migration on slopes shows both upward and downward movement, with predominant downward migration and deposition. Bedrock outcrops play a significant role in soil redistribution on karst slopes, hindering sediment transport and causing abrupt changes in rare earth element concentrations nearby. Monitoring and predicting soil erosion risk during the rainy season remains crucial for erosion prevention in karst regions. The impact of bedrock outcrops on soil erosion processes and spatial distribution in karst landscapes should be carefully considered when designing control measures. These findings offer a solid scientific foundation for understanding slope soil erosion mechanisms in karst regions and developing effective control strategies.