| 摘要: |
| 利用土柱切割法获得了饱和流运移土柱在不同运移时间的土壤溶质 (NH4+)剖面分布曲线 ,并提出溶质运移初始穿透时间 (T初)和完全穿透时间 (T末) 等概念以描述运移特征。在运移置换液浓度为 0.04 mol/L时 ,T初 、T末分别为 5、8左右 ,均比运移置换液浓度为0.08mol/L时的 T初(3.5左右 )和 T末 (6左右 )大 ;而在运移初始穿透时间时 ,运移置换液浓度为 0.04 mol/L时的土壤平均吸持量为 6.38～ 7.27cmol/kg,小于运移置换液浓度为 0.08mol/L时的土壤平均吸持量 (8.14～ 10.36cmol/kg) ,表明运移置换液浓度增大 ,溶质运移较快 ,土柱吸持的溶质数量平均水平较高。运移相对时间 (出流液的土柱孔隙体积数 )为 1～5,溶质峰移动深度随运移相对时间的延长而增大 ,运移置换液浓度为 0.04 mol/L时 ,土娄土的溶质峰移动深度与运移相对时间呈极显著线性正相关。根据化学动力学和过渡态理论 ,应用“S”型方程可定量描述饱和流运移过程土壤溶质吸持反应动力学特征。运移置换液浓度为0.08mol/L时的反应速率常数比运移置换液浓度为 0.04 mol/L时的反应速率常数大 2～3倍 ,相应的溶质吸持反应活化自由能变减小 ,表明运移置换液浓度增大 ,运移过程土壤溶质吸持反应速度加快。 |
| 关键词: 土壤物理化学,饱和流,溶质运移,溶质剖面分布 |
| DOI： |
| 分类号:S152 |
| 基金项目:国家自然科学基金资助项目(49901009),西北农业大学青年基金资助项目 |
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| Solute distribution on soil profile during saturated flow solute transport |
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WANG Yu ZHANG Yi-ping ZHENG Ji-yong ZHANG Jian-jun
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| Abstract: |
| NH4+ distribution on soil profile in different transport relative time during saturated flow solute transportwas determined with column destruction method. The transport relative time when the solute front reached the end boundary of soil columns was defined as the initial breakthrough time, and the transport relative time when the soil column was saturated by the transporting solute was defined as the thorough breakthrough time.When the displacement solution was 0.04mol/LNH4Cl,T初 and T末 were 5 and 8, respectively.When the displacement solution was 0.08mol/L NH4Cl,T初 and T末 were 3.5 and 6, respectively. At the initial breakthrough time, the average amount of solute adsorbed on soil solid when the displacement solution was 0.04mol/L NH4Cl was among 6.38- 7.27 cmol/kg, and when the displacement solution was 0.08mol/L NH4Cl, it was among 8.14 - 10.36 cmol/kg. It was clear that with increasing displacement solution transport,T初 and T末 decreased greatly, and the averageamount of solute adsorbed on soil solid at the initial breakthrough time increased, indicating that solute transported faster and in the meantime solute accumulation was greater.When transport relative time was among 1-5, the depth of solute front was positively linearly correlated with the transport relative time at 1% significant level.With chemical dynamics and transitional theory, the dynamic process of soil solute adsorption during solute transport was fitted properly by the“S”type equation. The reaction velocity constant when the displacement solution was 0.08mol/L NH4Cl was 2-3 times more than that when the displacement solution was 0.04mol/L NH4Cl.Accordingly, the corresponding bΔG++ decreased with increasing displacement solution concentration. |
| Key words: soil physical chemistry,saturated flow,solute transport,solute profile distribution |
