棕壤坡面颗粒有机碳流失对团聚体破碎的响应

The exposure of particle organic carbon (POC) because of aggregate breakdown during slope erosion is an important process affecting the mineralization of soil organic carbon and its cycling. However, the dynamic variation law of the amount of exposed POC because of aggregate breakdown and the transport mechanism of this part of POC accompanied by sediment in the subsequent runoff are not clear. To this end, we will select the typical brown soil sloping farmland in a northern rocky mountainous area to monitor the process of splash erosion, interill erosion and rill erosion with a field artificial rainfall simulation technology. The three-part runoff plots consist of the splash erosion compensation, splash erosion observation and slope erosion observation areas for the analysis of the transport law and influencing factors for POC with different particle sizes. The loss processes of POC from different aggregates are to be traced by 13C isotope labeling method for the quantification of physical protection loss due to aggregate breakdown for POC. The relationships between sediment sorting and POC loss are to be elucidated, and the response mechanism of POC loss to aggregate breakdown will be determined by exploring the regulation of sediment sorting and aggregate distribution characteristics. This study will help to assess the mineralization potential of soil organic carbon under the impact of water erosion and provide a theoretical basis for the improvement of organic carbon stock model for water erosion.

坡面侵蚀过程中，团聚体破碎暴露颗粒有机碳（POC）是影响土壤碳矿化与碳循环的重要过程。然而，团聚体破碎导致失去物理保护POC量的动态变化规律，以及该部分POC伴随泥沙的输移机制尚不明确。为此，本项目拟选取北方土石山区典型棕壤坡耕地，通过布设三分径流小区（包括溅蚀补偿区、溅蚀观测区和坡面侵蚀观测区），采用野外人工模拟降雨，监测溅蚀、片蚀和细沟侵蚀过程，分析不同粒径POC输移规律及其影响因子，并利用13C同位素技术示踪不同团聚体POC流失过程，明确不同侵蚀方式下侵蚀泥沙团聚体破碎导致失去物理保护POC的量，分析侵蚀过程中团聚体破碎和泥沙分选特征的基础上，阐明泥沙分选与POC流失的内在关系，揭示POC流失对团聚体破碎的响应机制。本项目将有助于评估侵蚀作用下土壤有机碳矿化潜力，且能够为侵蚀作用下土壤有机碳库预测模型的改进提供理论支撑。

坡面侵蚀过程中，团聚体破碎暴露有机碳是影响土壤碳矿化与碳循环的重要过程。然而，团聚体破碎导致失去物理保护有机碳的动态变化规律，以及该部分有机碳伴随泥沙的输移机制尚不明确。为此，本项目选取典型黄土坡耕地，通过布设三分径流小区（包括溅蚀补偿区、溅蚀观测区和坡面侵蚀观测区），采用人工模拟降雨，监测溅蚀与片蚀侵蚀过程，分析水蚀过程中团聚体破碎与输移特征，揭示了侵蚀泥沙各粒径团聚体有机碳不均匀富集及其水动力学特征，阐明了各粒径泥沙颗粒有机碳流失规律与量，推断了不同有机碳/矿物泥沙颗粒输移规律，同时发现了侵蚀过程存在一定的有机碳同位素分馏效应。本项目将有助于评估侵蚀作用下土壤有机碳矿化潜力，且能够为侵蚀作用下土壤有机碳库预测模型的改进提供理论支撑。