| 摘要: |
| 【目的】 探明不同地下水位深度条件下，地表径流过程中溶质的迁移规律。【方法】 采用模拟试验，研究3种地下水位(地下水位与地表持平、低于地表5和10 cm)及不同地表径流流速下（90，120，200，250 mL/s），土壤溶质迁移到地表径流过程中,其在3种途径（土壤侵蚀、伯努利效应、扩散）下的变化规律。【结果】 当地表径流流速小于 200 mL/s时，随着地表径流流速的增加，土壤溶质流失加剧，伯努利效应和扩散作用是引起土壤溶质流失的主导因素；当地表径流流速大于200 mL/s时，土壤侵蚀是引起土壤溶质流失的主导因素。径流60 min后，当地下水位低于地表5～10 cm时，随着土层深度的增加，土壤剖面中溴化物质量浓度则逐渐增大。当地下水位与地表持平时，混合层深度为0.9~4.6 mm；当地下水位低于地表5和10 cm时，混合层深度均小于2.5 mm。【结论】 土壤溶质迁移过程与地表径流流速和地下水位高低有重要关系。 |
| 关键词: 土壤 地下水位 土壤溶质 地表径流 |
| DOI： |
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| 基金项目:美国农业部项目“土壤水动力及其在土壤侵蚀和水质的有效管理项目” (3602-12220-009-00) |
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| Chemical transport from soil into surface runoff under different ground-water tables |
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LIU Yong hong LIANG Zong suo YANG Dong feng LIU Wen ting
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| Abstract: |
| 【Objective】 The study was conducted to prove chemical transport processes under different soil hydrologic conditions.【Method】 We developed a laboratory flow cell and experimental procedure to quantify chemical transport from soil to runoff water by each of the individual process:1) erosion;2) Bernoulli effect;and 3) diffusion under groundwater table with the same height, 5 cm,and 10 cm beneath the soil surface by 4 kinds of surface runoff flow rates (90，120，200，250 mL/s).【Result】 Our data proved that soil chemical loss aggravated as runoff flow rate increased;nevertheless,we had additional quantitative data describing the contribution from each individual chemical loading process under different surface runoffs and soil hydrologic conditions.When surface runoff velocity was less than 200 mL/s,Bernoulli effect and diffusion had a great contribution to chemical loss from soil to runoff.On the contrary,erosion was the dominant factor for chemical loss.After 60 min surface runoff,when groundwater table was 5-10 cm lower than soil surface.Bromide concentration increased in soil profile as soil depth increased.According to our data,the mixing zone depth reached between 0.9-4.6 mm when the under groundwater table was of the same height with soil surface,and less than 2.5 mm when the under groundwater was 5-10 cm lower than soil surface.【Result】 Chemical transport has a significant relationship with surface runoff flow rate and groundwater table. |
| Key words: soil ground-water table soil chemical surface runoff |
