利用风洞实验研究~7Be示踪估算土壤风蚀速率的可行性

以黄土高原水蚀风蚀交错带沙黄土为研究对象,利用室内风洞模拟实验对7Be示踪估算土壤风蚀速率的可行性进行探讨。由于风蚀过程易带走土壤细颗粒,且7Be在土壤细颗粒中含量较高,所以利用7Be水蚀模型计算的土壤风蚀速率高于实测值。实验中发现样点风蚀后和风蚀前土壤颗粒比表面积之比与样点风蚀后7Be含量之间存在幂函数关系,基于此,提出颗粒校正系数(P)的计算式,并将P引入到7Be水蚀模型对其进行修正。计算分析发现,和实测值相比,利用修正模型计算的土壤风蚀速率误差均不超过5%,这说明经过修正的7Be水蚀模型能较准确地估算土壤风蚀速率,利用7Be示踪技术估算土壤风蚀速率是可行的。研究为进一步利用7Be示踪技术调查黄土高原水蚀风蚀交错带土壤风蚀问题奠定了基础。

Wind Tunnel Feasibility Study on Using 7Be Technique to Estimate Soil Wind Erosion Rate

In this study,sandy loess from the wind-water erosion crisscross region on the Loess Plateau of China was used in wind tunnel to test the feasibility of using 7Be technique to estimate wind erosion rate.Since wind erosion selectively removes finer particles of soil,the direct use of 7Be-based water erosion model tends to overestimate wind erosion rate as 7Be is preferentially associated with the fine particles.The results showed an exponential function relationship between Se/So and the concentration of 7Be at the eroded site(Se and So are the specific surface areas of eroded soil and the original soil,respectively).Thus,a particle size correction factor(P) was incorporated into the 7Be-based water erosion model.The wind erosion rates calculated by the corrected model were within 5% error compared with the measured values,indicating that the corrected model estimates wind erosion rate fairly accurately and that the 7Be technique could be used to estimate wind erosion rate.This study laid a foundation for further utilizing 7Be technique to investigate wind erosion in the wind-water erosion crisscross region on the Loess Plateau of China.