利用土壤颗粒的沉降粒级研究泥沙的迁移与分布规律

发布时间：2018-05-13 06:24

  本文选题：沉降管法 + 沉降速度　； 参考：《土壤学报》2017年05期

【摘要】：了解不同粒径泥沙迁移运动规律,有助于深入理解侵蚀条件下碳、氮、磷等元素的生物地球化学过程。土壤营养元素的迁移转化与泥沙颗粒的运动规律密切相关,而泥沙的运动规律由颗粒大小、性状、孔隙度和密度等因素共同决定。依据泥沙颗粒沉降速度分选的原理,针对中国两种典型侵蚀土壤(红壤和黄绵土),分别进行了土壤机械组成(矿质土粒分选)和沉降速度分选测定。结果表明,土壤颗粒的沉降粒级可有效区分红壤和黄绵土中不同粒径团聚体的沉降速度,能够更加准确地反映出同一粒径颗粒因性状、密度和孔隙度的差异而形成的不同沉降速度。相对于质地疏松的黄绵土,红壤的机械组成显示,有86.9%的有机碳与≤32μm的矿物颗粒相结合,很有可能随悬移过程汇入下游水体。但土壤颗粒沉降速度分布表明,约有90.5%的红壤有机碳与等效石英粒径≥63μm的团聚体相结合,易在经历较短的迁移过程后,快速沉积于下坡面。这表明,现有的土壤侵蚀模型大多利用土壤机械组成(即矿质粒径大小)在反映泥沙运动或元素迁移规律方面存在片面性。土壤的团聚过程可有效缩减有机碳和无机碳的迁移距离,从而使其更易沉积于陆生环境。土壤颗粒的沉降速度分级对认识泥沙颗粒和养分元素在侵蚀—迁移—沉积过程中的生物地球化学过程提供了新的途径和视角。
[Abstract]:It is helpful to understand the biogeochemical processes of carbon, nitrogen, phosphorus and other elements under erosion conditions. The transport and transformation of soil nutrient elements are closely related to the movement of sediment particles, while the movement of sediment is determined by the particle size, characteristics, porosity and density. According to the principle of sedimentation velocity separation of sediment particles, two typical eroded soils (red soil and yellow spongy soil) in China were determined by soil mechanical composition (mineral soil particle sorting) and settling velocity separation respectively. The results show that the sedimentation particle size of soil particles can effectively distinguish the settling velocity of different aggregates in red soil and yellow cavernous soil, and can more accurately reflect the characteristics of particle size of the same size. The difference in density and porosity resulted in different settlement rates. Compared with the loose yellow spongy soil, the mechanical composition of red soil shows that 86.9% of the organic carbon is combined with mineral particles 鈮，

本文编号：1882048