不同前处理方法对紫色土粒度测试的影响.

[Objective] It is of great significance for clarifying the influence of different pretreatment methods on the measurement of soil particle composition(PSD), which is the basis of studies on water transport, nutrient transport, soil erosion and sediment transport processes. Soil particle composition(PSD) is the basis of soil physical properties and has important implications for [Methods] Typical purple soil natural woodland profile soil(0-110 cm) was selected, and 9 pretreatment methods were adopted, including physical methods of soaking and shaking, and chemical methods of H2O2 and HCl treatment, and then particle analysis was carried out with a Mastersizer 2000 laser particle size analyzer. [Results](1) The median particle size of each physical pretreatment decreased by 33.79 μm on average compared with the direct measurement without any pretreatment(control). The median particle size under pretreatments of soaking, shaking for 2 h, and shaking for 10 h decreased sequentially, but their release effects on clay were weak. There was no significant difference in clay content between different shaking times(p＞0.05). The median particle size of each chemical treatment could be reduced by 32.72 μm on average compared with control. Among them, the H2O2 treatments had a stronger dispersing effect than the HCl treatments, and the clay contents of H2O2 treatments were the highest among all treatments, which were greater than 4%.(2) Each physical pretreatment method had a uniform dispersion effect among soil layers. Sensitivity to different H2O2 dosage of different layer of soil was middle(30-70 cm)＞lower(70-110 cm)＞upper(0-30 cm). Specifically, sand content in the 20-90 cm soil layer under sufficient H2O2 pretreatment increased by 9.5% and silt content decreased by 9.7% compared with 10 ml H2O2 pretreatment. Sensitivity to different HCl pretreatments of different layer of soil was upper and middle＞lower, specifically the sand content of the upper and middle soil(0-90 cm) increased by 6.2% on average under the treatment of 10 ml HCl plus acid washing compared with the treatment without acid washing. The silt content reduced by an average of 5.4%. There was no significant difference in clay content among soil layers under these treatments.(3) There was a significant linear correlation(r＞0.8) between the content of sand and silt and the content of organic matter in the profile under the treatment of sufficient H2O2, but there was no significant correlation between the content of calcium carbonate and any particles under the treatment of HCl. [Conclusion] There are significant differences in PSD between different pretreatment methods, and the amount of reagent in chemical pretreatments affects the PSD obviously, too. This study can provide a reference for the analysis of purple soil particle composition under different research purposes. [ABSTRACT FROM AUTHOR]