吸管法与扫描电镜法测定中国水蚀区典型土壤粒径分布对比
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S152.3

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国家自然科学基金项目“黄土高原植被恢复影响切沟侵蚀的动力机制与模拟”(42130701);地表过程与资源生态国家重点实验室重点项目“典型黑土区冻融循环特征及其对水力侵蚀的影响机制”(2021-ZD-05)


Comparison of Particle Size Distributions Determined by Pipette Method and Scanning Electron Microscopy for Typical Soils in Water Erosion Region of China
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    [目的] 利用扫描电镜法(scanning electron microscopy, SEM)评估吸管法(pipette method, PM)对中国水蚀区不同土壤粒径分布(particle size distribution, PSD)的测定结果,以期为各典型土壤PSD的测定及其结果在土壤侵蚀模型中的应用提供参考。[方法] 以5个水蚀二级区的典型土壤——黑土、褐土、黄土、紫色土和红壤为研究对象,利用SEM测定PM所得<100 μm各粒级悬液的粒径分布,分析两种方法测得的粒径分布差异并探讨其原因。[结果] PM所得绝大多数土壤悬液中都存在粒径大于对应粒级的颗粒。随着悬液粒级减小,SEM所得相应粒级颗粒的数量百分比和体积百分比均降低。在<100 μm悬液中,SEM测得黑土、褐土和紫色土颗粒集中于20~53 μm,平均体积直径(mean volume diameter, MVD)较小;黄土和红壤颗粒集中于20~53,53~100 μm,MVD较大。相比SEM,PM对黄土<100 μm悬液PSD的测定结果差异不大,但高估了其余土壤<2 μm黏粒含量,低估了黑土、褐土和紫色土20~53 μm粒级含量及红壤20~100 μm含量,所测各土壤平均重量直径(mean weight diameter, MWD)均小于SEM所测MVD。PM与SEM所测土壤PSD的差异使85.6%的土壤样品质地类型发生了变化。通过S曲线对PM所测PSD进行转换后可使质地类型不一致的样品占比下降至61.5%。[结论] 以SEM结果为基准,PM对水蚀区各土壤粒径分布的测定普遍存在误差。两种方法之间的差异因土壤类型而异,主要与土壤矿物组成和黏土矿物类型有关。

    Abstract:

    [Objective] The particle size distributions (PSD) of different soils measured by scanning electron microscopy (SEM) and by the pipette method (PM) in the water erosion region of China was compared in order to provide a reference for the determination of typical soil PSDs and their applications in soil erosion models.[Methods] Five typical soils corresponding to the five water erosion subregions of China (i.e., black soil, cinnamon soil, loess, purple soil, and red soil) were collected and analyzed by PM and SEM. Specifically, soil suspensions of different size classes obtained by PM (i.e., < 100, < 53, < 20, < 10, < 5 and < 2 μm) were measured using SEM. The PSD results determined by PM and SEM were compared and the causes for their difference were determined.[Results] For most soil suspensions obtained by PM, particles larger than the corresponding size classes of the suspensions were detected by SEM. As the size classes of soil suspensions decreased, both the count and volume fractions of the corresponding sizes, as measured by SEM, decreased. For the suspensions < 100 μm, the particles of the black, cinnamon, and purple soils fell mainly in the 20-53 μm class, resulting in relatively lower values of SEM-derived mean volume diameter (MVD). In contrast, the primary size classes of the loess and red soil were 20-53 and 53-100 μm, leading to larger MVD. Little difference was observed in the PSDs of loess between PM and SEM for the suspension < 100 μm. Compared with SEM, PM overestimated the clay fractions < 2 μm of the other soil samples, and underestimated the size fractions of 20-53 μm for the black, cinnamon, and purple soils, as well as the fractions of 20-100 μm for the red soil. As a result, the PM-derived mean weight diameters (MWD) were smaller than the SEM-derived MVD for all of the investigated soils. Additionally, the PSD discrepancies between the two analytical methods shifted the textural classes of 84.6% of the total soil samples. Converting the PM-derived PSD with the optimal S-curve models, the proportion of the samples with different textural classes due to PSD analytical method decreased to 61.5%.[Conclusion] Based on the SEM results, PM tended to misestimate the PSDs of all of the five typical soils in the water erosion region. The PSD differences between the two methods varied with soil type and were mainly related to soil mineral composition and clay mineral types.

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彭婷婷,白雪,杨扬,高晓飞,刘瑛娜.吸管法与扫描电镜法测定中国水蚀区典型土壤粒径分布对比[J].水土保持通报,2023,43(3):165-175

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  • 收稿日期:2022-09-13
  • 最后修改日期:2022-11-01
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  • 在线发布日期: 2023-08-16
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