An experimental study on behaviors of water and chemicals in a non-uniform soil layer and its mechanism under evaporation

蒸发条件下非均匀土层中水和化学物质的行为及其机理的实验研究

• 批准号: 17560464
• 负责人: SHIMOJIMA Eiichi
• 金额: $ 1.54万
• 依托单位: Daido Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17560464/
• 关键词: evaporation experiment; Akadama-soil; dual pore structure; salinization; evaporation-condensation; vapor transfer; 空隙2重構造

In arid and semi-arid areas, evaporation and salinization becomes quite important phenomena which must be to clarified. In this study, Akadama-soil layers with a dual pore structure (macro-pores and micro-pores) were focused on as a non-uniform soil, and evaporation experiments using the layers moistened by distilled water and enriched NaCl solution were undertaken in a temperature and humidity controlled room at 25℃ and 20%. To examine effects of a solar radiation, water-table and turbulent surface wind to evaporation, in some cases, such conditions were applied to the layer. Through the evaporation experiments, the following are clarified.1.Micro-pores play a role of transmission route of underlying soil-water to an evaporation zone, and it causes evaporation rate higher.2.Turbulence of applied surface wind to the exposed surface penetrates easily into soil through macro-pores, and it affects vapor transfer in the soil layer significantly. Therefore, in the vapor transfer in the soil layer, not only molecular diffusion but also turbulent one caused by the surface wind must be taken account3.The heating on the upper surface leads a characteristic vapor density profile in the soil with a peak at which the evaporation zone is located. Water vapor created by evaporation is transported in the upper and lower directions. The downward moving vapor condenses in a deep location, therefore soil-water is carried to a deep zone via evaporation, vapor transfer and condensation process.4.Enrichment of soil-water appears in an upper zone of the soil layer, where the concentrations of Na+ and Cl start to increase abruptly with decreasing depth. This location is more or less consistent with the upper end of drying front. The concentrations below that depth, as a result, become lower than initial ones・this may be due to absorption and ion exchange on the soil-particles.

在干旱和半干旱地区，经济和盐水化成为非常重要的现象，必须澄清。在这项研究中，将具有双孔结构（宏pores和微孢子）的Akadama-ail层集中在不均匀的土壤中，并且在25°和20％的温度和湿度控制的房间中，在温度和湿度控制的房间中进行了使用蒸馏水和富含NACL溶液湿润的层经济实验。为了检查太阳辐射的影响，水表和湍流的表面风能蒸发，在某些情况下，将这种情况应用于该层。通过蒸发实验，阐明了以下内容。1.Micro-Pores起着下层土壤水向蒸发区的传播途径的作用，并导致蒸发速率更高。2。施加的表面风向暴露于暴露的表面轻松地穿透了宏观孢子，并影响土壤中的蒸发层的蒸发。因此，在土壤层中的蒸气转移中，不仅必须采用分子扩散，而且还必须采用由表面风引起的湍流。3。上表面上的加热导致土壤中特征性的蒸气密度分布，其峰值在其经济区的峰值。经济产生的水蒸气是在上下方向运输的。在深处的向下移动蒸气凝结，因此通过经济，蒸气转移和冷凝过程将土壤水带到一个深区域。4。土壤水分出现在土壤层的上部区域中，其中Na+和Cl的浓度随着深度的降低而开始突然增加。该位置或多或少与干燥前端的上端一致。结果，低于该深度的浓度低于初始浓度・这可能是由于土壤粒子上的苦难和离子交换所致。