Nie Xiaodong, Li Zhongwu, Huang Jinquan, Huang Bin, Zhang Yan, Ma Wenming, Hu Yanbiao, Zeng Guangming
College of Environmental Science and Engineering, Hunan University, Changsha, PR China; Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha, PR China.
Department of Soil and Water Conservation, Yangtze River Scientific Research Institute, Wuhan, PR China.
PLoS One. 2014 Aug 28;9(8):e105927. doi: 10.1371/journal.pone.0105927. eCollection 2014.
The study on the lateral movement of soil organic carbon (SOC) during soil erosion can improve the understanding of global carbon budget. Simulated rainfall experiments on small field plots were conducted to investigate the SOC lateral movement under different rainfall intensities and tillage practices. Two rainfall intensities (High intensity (HI) and Low intensity (LI)) and two tillage practices (No tillage (NT) and Conventional tillage (CT)) were maintained on three plots (2 m width × 5 m length): HI-NT, LI-NT and LI-CT. The rainfall lasted 60 minutes after the runoff generated, the sediment yield and runoff volume were measured and sampled at 6-min intervals. SOC concentration of sediment and runoff as well as the sediment particle size distribution were measured. The results showed that most of the eroded organic carbon (OC) was lost in form of sediment-bound organic carbon in all events. The amount of lost SOC in LI-NT event was 12.76 times greater than that in LI-CT event, whereas this measure in HI-NT event was 3.25 times greater than that in LI-NT event. These results suggest that conventional tillage as well as lower rainfall intensity can reduce the amount of lost SOC during short-term soil erosion. Meanwhile, the eroded sediment in all events was enriched in OC, and higher enrichment ratio of OC (ERoc) in sediment was observed in LI events than that in HI event, whereas similar ERoc curves were found in LI-CT and LI-NT events. Furthermore, significant correlations between ERoc and different size sediment particles were only observed in HI-NT event. This indicates that the enrichment of OC is dependent on the erosion process, and the specific enrichment mechanisms with respect to different erosion processes should be studied in future.
关于土壤侵蚀过程中土壤有机碳（SOC）侧向移动的研究有助于加深对全球碳收支的理解。通过在小型田间地块上进行模拟降雨实验，研究不同降雨强度和耕作方式下SOC的侧向移动情况。在三块地块（宽2米×长5米）上设置了两种降雨强度（高强度（HI）和低强度（LI））以及两种耕作方式（免耕（NT）和传统耕作（CT））：HI-NT、LI-NT和LI-CT。径流产生后降雨持续60分钟，每隔6分钟测量并采集沉积物产量和径流量。测量沉积物和径流中的SOC浓度以及沉积物粒径分布。结果表明，在所有情况下，大部分侵蚀的有机碳（OC）以与沉积物结合的有机碳形式流失。LI-NT情况下流失的SOC量比LI-CT情况下大12.76倍，而HI-NT情况下该数值比LI-NT情况下大3.25倍。这些结果表明，传统耕作以及较低的降雨强度可以减少短期土壤侵蚀过程中SOC的流失量。同时，所有情况下侵蚀的沉积物中OC都有富集，LI事件中沉积物中OC的富集率（ERoc）高于HI事件，而LI-CT和LI-NT事件中ERoc曲线相似。此外，仅在HI-NT事件中观察到ERoc与不同粒径沉积物颗粒之间存在显著相关性。这表明OC的富集取决于侵蚀过程，未来应研究不同侵蚀过程的具体富集机制。
