降雨条件下土壤胶结状况与团聚体分布特征研究  

Study on Soil Cementation and Aggregate Distribution Characteristics Under Rainfall Conditions

作　　者：焦钒栩 侯卫亮 李光录[1] Jiao Fanxu;Hou Weiliang;Li Guanglu(College of Natural Resources and Environment,Northwest A&F University,Yangling,Shaanxi 712100,China)

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100

出　　处：《水土保持研究》2024年第6期109-118,共10页Research of Soil and Water Conservation

基　　金：国家自然科学基金“黄土高原土壤侵蚀过程中团聚体循环破坏机制和微观结构”(41571262)。

摘　　要：[目的]分析雨滴击溅对表层土壤胶结剂含量以及团聚体分布特征的影响,揭示降雨条件下土壤胶结状况与团聚体变化的关系。[方法]通过室内模拟降雨试验,采用理化分析与同步辐射计算机扫描(SR-μCT)技术,对泥沙中团聚体胶结剂含量、表土团聚体空间分布进行了研究。[结果](1)泥沙中各胶结剂含量排序为碳酸钙>有机碳>游离氧化铁>游离氧化铝>六碳糖,相同薄层径流下,泥沙中胶结剂的含量随雨滴直径的增加不断增加;相同雨滴直径下,胶结剂的含量随薄层径流的增加呈先增加后减小的波动式变化。雨滴击溅和径流冲刷共同作用对<0.053 mm粒径下六碳糖、游离氧化铁、游离氧化铝以及0.25~2 mm粒径下六碳糖、游离氧化铁、碳酸钙和有机碳含量影响显著(p<0.05)。(2)相同薄层径流下,表土团聚体总数量(A)、微团聚体(≤0.25 mm)数量、比表面积(SSA)随雨滴直径的增加而增加,大团聚体体积百分比(V mac)、大团聚体(>0.25 mm)数量、几何平均直径(GMD)随雨滴直径的增加而减小;相同雨滴直径下,随着薄层径流增加,SSA不断减小,GMD不断增加。(3)泥沙中5种胶结剂与表土团聚体结构参数呈显著相关关系(p<0.05),泥沙胶结剂含量越高,A和SSA越大,GMD和V mac越小。[结论]雨滴击溅薄层径流增加了表土团聚体胶结剂迁移损失,增大泥沙中胶结剂的含量。降雨侵蚀下表土团聚体胶结剂含量降低,是导致土壤团聚体结构破坏,稳定性降低的主要原因。[Objective]The aims of this study are to analyze the influence of raindrop splash on the content of soil cement and the distribution characteristics of soil aggregates in the surface soil layer,and to reveal the relationship between the soil cementation status and the changes of aggregates under rainfall conditions.[Methods]Study on the content of aggregates cement in the sediment and the spatial distribution of topsoil aggregates were investigated by indoor simulated rainfall tests,physicochemical analyses and synchrotron radiation computer scanning(SR-μCT)technology.[Results](1)The order of the content of each cement in the sediment was calcium carbonate>organic carbon>free iron oxide>free alumina>six-carbon sugar.The content of the cement in the sediment increased with the increase of the raindrop diameter under the same thin-layer runoff.The content of the cement showed a fluctuating change of increasing and then decreasing with the increase of the thin-layer runoff under the same raindrop diameter.The combined effect of raindrop splash and runoff washout on the content of six-carbon sugar,free iron oxide,free aluminium oxide at<0.053 mm particle size and six-carbon sugar,free iron oxide,calcium carbonate and organic carbon at 0.25~2 mm particle size was significant(p<0.05).(2)Under the same thin-layer runoff,the total number of aggregates(A),the number of microaggregates(<0.25 mm),and the specific surface area(SSA)increased with the increase of raindrop diameter in topsoil.The volume percentage of macroaggregates(V mac),the number of macroaggregates(>0.25 mm),and the geometric mean diameter(GMD)decreased with the increase of raindrop diameter.For the same raindrop diameter,with the increase of thin-layer runoff,the SSA decreased and the GMD increased.(3)The five types of binder in the sediment were significantly correlated with the structural parameters of the topsoil aggregates(p<0.05).The higher the content of binder in the sediment,the larger the A and SSA,and the smaller the GMD and V mac.[Conclusions]R

关 键 词：雨滴击溅 薄层径流 胶结剂 团聚体微观结构 

分 类 号：S152.4[农业科学—土壤学]