Effect of macropore number and size combination on solute transport in soil

Journal Information

J. Hefei Univ. Tech. (Nat. Sci.), Aug.2025, Vol.48 No.8: 1146-1152

DOI: 10.3969/j.issn.1003-5060.2025.08.021

Authors

ZHANG Ruigang $ ^{1,2} $, TANG Zhiheng $ ^{1} $, HUAN Xiaoxiang $ ^{1} $, XIA Bing $ ^{3} $, QIAN Jiazhong $ ^{4} $

(1. School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China; 2. Bengbu Investment Group Co., Ltd., Bengbu 233499, China; 3. Anhui Provincial Academy of Eco-Environmental Science Research, Hefei 230071, China; 4. School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China)

Abstract and Keywords

Abstract: A large number of field observations and experiments have shown that the macropore preferential channels with different densities, numbers and sizes formed by plant root development and earthworm activities affect the transport characteristics of water and solute preferential flow. Currently, more attention has been paid to the effect of macroporosity, while less to the effect of different number and size combinations with the same macroporosity. In this paper, solute transport experiments of soil columns with three different macropore number and size combinations with the same macroporosity and one homogeneous soil column were conducted to explore the effects of the combinations on water and solute transport in soil. The dual permeability model in Hydrus was used to investigate their effects in numerical simulation. The results show that under the same macroporosity, the discharge rate of the soil column with fine and more macropore combination is faster, the average residence time of solute is shorter, and the degree of preferential flow is higher. In the dual permeability model, the change of the number and size combination of macropores is reflected by the parameter a, and the value of a is smaller for fine and more macropore combination. The effect of a on solute transport is that, with a smaller value of a, the breakthrough will be faster and more concentrate, and peak concentration value is higher, but initial penetration is later.

Keywords: preferential flow; macroporosity; percolation experiment; breakthrough curve; dual permeability model

作者信息

张瑞钢 $ ^{1,2} $，汤志恒 $ ^{1} $，还小翔 $ ^{1} $，夏冰 $ ^{3} $，钱家忠 $ ^{4} $

（1. 合肥工业大学土木与水利工程学院，安徽合肥 230009；2. 蚌埠投资集团有限公司，安徽蚌埠 233499；3. 安徽省生态环境科学研究院，安徽合肥 230071；4. 合肥工业大学资源与环境工程学院，安徽合肥 230009）

摘要和关键词

摘要: 大量野外观测与试验表明, 土壤因植物根系发育、蚯蚓活动等形成的不同密度、数量和孔径的大孔隙优势通道影响水分和溶质优势流运移特征。当前对大孔隙度影响的关注较多, 而对相同大孔隙度条件下因数量和孔径组合不同带来的影响关注不足。文章通过相同大孔隙度的 3 组不同数量和孔径组合的土柱及对照均质土柱的溶质运移试验, 探究其对土壤水分和溶质运移的影响, 并利用 Hydrus 中的双重渗透模型探究其在数值模拟中的影响。结果表明: 相同大孔隙度条件下细而多的大孔隙组合土柱出流速度更快, 溶质平均停留时间更短, 优势流程度更高; 在双重渗透模型中大孔隙数量和孔径组合的改变由参数 a 体现, 且细而多的大孔隙组合 a 取值更小; a 对溶质运移结果的影响表现为 a 值越小, 溶质穿透更快、更集中, 峰值质量浓度更高, 但是初始穿透更晚。

关键词: 优势流；大孔隙度；渗流试验；穿透曲线；双重渗透模型

Funding

国家自然科学基金资助项目（41831289）；安徽省自然科学基金资助项目（200805MD107）

合肥工业大学学报(自然科学版)

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