国家自然科学基金项目( 41877080, 42177338 )和陕西省林业科学院黄土高原生态修复创新团队项目(SXLK2020-03-02) 资助
1.Institute of soil and water conservation,CAS & MWR;2.Northwest A&F University
Supported by the National Natural Science Foundation of China ( Nos. 41877080，42177338 ) and Loess Plateau Ecological Restoration Innovation Team, Shaanxi Academy of Forestry(No.SXLK2020-03-02).
细沟间和细沟侵蚀剥离和输移土壤的机制，不同导致有机碳输移存在差异，然而因研究手段限制，这两种侵蚀方式对有机碳输移的贡献、影响等研究有待深入。本文利用模拟降雨与7Be示踪技术，在定量化分析细沟间和细沟侵蚀对黄土坡面侵蚀产沙贡献的基础上，进一步分析了其对有机碳输移的贡献及影响。结果显示5°小区以细沟间侵蚀为主，其产沙贡献率为86%，大于5°的小区以细沟侵蚀为主，其产沙贡献率在61%～71%之间，在降雨过程中甚至可达96%。降雨过程中坡面侵蚀泥沙有机碳平均富集比为1.16±0.15，细沟间侵蚀泥沙有机碳平均富集比为1.50±0.50，富集可导致有机碳流失率增加0.008～0.028 g m-2 min-1。坡度大于5°的小区细沟侵蚀对有机碳流失贡献率在55%～62%之间，低于对侵蚀产沙的贡献，但仍占主导地位。坡面侵蚀产沙量可解释有机碳流失量变化的97%，细沟间侵蚀产沙可解释细沟间有机碳流失量变化的89%。侵蚀过程中剧烈的细沟侵蚀可导致细沟间侵蚀泥沙有机碳的富集比增大。
【Objective】The differences in soil detachment and transport mechanisms between interrill and rill erosion lead to the differences in organic carbon loss by interrill and rill erosion. However, few studies were conducted to explore the effects and contributions of interrill and rill erosion on organic carbon loss during the erosion process because of the limitation of research methods. Successful use of the radionuclide 7Be to document soil erosion provides a means of addressing this need. The objectives of this study were to first estimate the contribution of interrill and rill erosion to sediment yield and then quantitatively explore the effects and contributions of interrill and rill erosion on organic carbon loss on the loess slope. 【Method】The simulated rainfall experiments with five slope gradients (5°, 10°, 15°, 20°, 25°and 30°) were conducted under different rainfall intensities in the field to investigate soil and organic carbon loss and 7Be tracing technology was used to quantify the contribution rate of interrill and rill erosion on sediment yield and organic carbon loss for the loess slope.【Result】Interrill erosion is the main and the relative contribution of interrill erosion on sediment yield was 86% on the 5°plot. But rill erosion dominated on the plots with gradient greater than 5°. The relative contribution of rill erosion on sediment yield ranged from 61% to 71% and could even reach 96% during the rainfall. The average enrichment ratio of organic carbon of sediment from the entire plot and the interrill area was 1.16±0.15 and 1.50±0.50, respectively, during the rainfall. The enrichment could increase organic carbon loss rate of 0.008 to 0.028 g m-2 min-1. The relative contribution of rill erosion to organic carbon loss were between 55% and 62% on plots with gradient greater than 5°, which were lower than those of rill erosion to sediment production, but still dominated. Sediment yield from the entire plot and the interrill area could respectively explain 97% and 89% of the variations of organic carbon loss from the entire plot and the interrill area. 【Conclusion】The organic carbon enrichment ratio had less effects on organic carbon loss when rill erosion occurred severely. Sediment yield determined the amount of organic carbon loss. Severe rill erosion could enhance the enrichment ratio of organic carbon of sediment from the interrill area.
ZHANG Fengbao, LI Xuantian, SHEN Nan, YANG Mingyi. Quantitatively Partitioning Organic Carbon Loss by Interrill and Rill Erosion on The Loess Slope[J]. Acta Pedologica Sinica, DOI:10.11766/trxb202201290040,[In Press]