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| Abstract: |
| A phreatic water evaporation experiment, without rainfall influence, was designed to study the mechanisms of soil water movement through groundwater recharge to the unsaturated zone. Soil moisture content, chloride concentration, and D and 18O values of soil water were measured. Results show that with decreasing soil moisture content, the chloride concentration of leachate (ρf(Cl)) in the capillary water layer decreases, whereas the ρf(Cl) value of the hanging and film water layers above the capillary water layer increases. With the combined D and 18O values, the soil water in the hanging and film water layers is influenced by evaporation, although a dry sand layer of 39 cm exists above the wet sand layer. The highest evaporation rate and the largest salt accumulation occur at a depth of about 39 cm in columns d, e, and f (Six polyvinyl chloride columns were assigned as column a, b, c, d, e, and f). We deduce that soil water migrates in the form of liquid water above the capillary water layer. In the experiment, a part of phreatic water consumed is used for the movement of soil water, whereas the other part is lost to evaporation. Soil water could continue migrating upward with prolonged experiment duration. |
| Key words: soil water chloride stable isotope film water phreatic water evaporation |
| DOI：10.11916/j.issn.1005-9113.17099 |
| Clc Number:P592 |
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| Descriptions in Chinese: |
| 潜水蒸发过程中土壤水氢氧同位素和氯离子含量示踪水分运移规律 孙晓旭1，徐 进1，陈建生2 (1.南京工程学院 环境工程学院，南京 211167；2.河海大学 地球科学与工程学院，南京 210098) 创新点说明：1）氯离子含量和土壤水氢氧同位素结合使用示踪潜水蒸发过程中土壤水的运移规律； 2）结果表明，潜水蒸发过程中，在毛管水活动层之上是通过液态水往上运移的。 研究目的： 研究潜水蒸发补给非饱和带过程中，毛管水活动层之上的土壤水分在剖面中的运移规律。 研究方法及设备： 1）在室内设计6个平行土柱，模拟潜水蒸发的过程，控制土柱上方的空气湿度，在不同的蒸发时间、土柱不同的层位采集土壤样品，分析土壤含水率、土壤水氯离子含量和氢氧同位素值随剖面深度的变化规律，来研究潜水蒸发过程中土壤水的运移规律； 2）所采用主要仪器包括：测定氯离子含量采用戴安公司的离子色谱仪（ICS-2000）、氢氧同位素测试采用稳定同位素质谱仪MAT253 结果： 通过不同土柱土壤水氯离子含量和氢氧同位素值随剖面深度的变化规律可看出，潜水蒸发补给非饱和带过程中，在毛管水活动层之上是通过液态水往上运移的，土柱上方空气中湿度越低，土壤水蒸发越强烈。 结论： 潜水蒸发过程中，土壤水通过液态水往上运移，氯离子在蒸发最强烈的层位累积最明显，即使湿砂层上方有39cm的干砂层存在，土壤水仍然存在蒸发，如果蒸发时间延长，水分将继续往上运移。在本文试验中提到的薄膜水层具有与毛管活动水层不同的水盐分布特征，水分是靠吸着力所保持的，实验中可以看出剖面中土壤水有蒸发损失，又有潜水不断的通过薄膜水的补给，但是土壤水产生蒸发和薄膜水运移的动力等问题还需要进一步深入的研究。 关键词：土壤水;氯离子;稳定同位素;薄膜水;潜水蒸发 |
