中文摘要：

为深入探究沟灌覆膜条件下土壤水分运动规律及其转化机理,利用了稳定氢氧同位素技术分析了土壤水和膜下凝结水的同位素分布特征。表明,膜下凝结水富集~（18）O,富集程度明显高于由表层土壤蒸发而富集的重同位素;膜下表层土壤蒸发后凝结于膜下形成水珠的过程经历了重同位素贫化后再富集,之后凝结水发生二次蒸发,重同位素再次富集;覆膜沟灌下土壤水氧同位素随土壤深度呈梯度分布,垄上富集~（18）O比沟中显著;沟中蒸发前缘发生在0~10cm土层,土壤水直接以水汽分子形式扩散到大气中;垄上蒸发前缘主要发生在10~20cm土层,蒸发水汽分子通过土壤孔隙向上扩散,部分水汽分子被0~10cm的土壤水吸附并与其水分子发生交换进而扩散到土壤表面。

英文摘要：

In order to further clarify the mechanism of soil water movement under plastic film -mulching furrow irrigation ,the distri‐butions of δD andδ 18 O distribution in soil water and condensation water adhered in plastic film were analyzed .Results showed that 18 O was enriched in condensation water and its enrichment was much larger than that in surface soil which resulted from evaporation . Heavy isotope depleted and enriched alternative along with the process of condensation of evaporation vapor ,then it enriched again when the second evaporation occurred in condensation water .Theδ 18O in soil water profile decreased with depth under plastic film-mulching furrow irrigation ,and 18 O enriched in the ridge was larger than that in furrow .The soil evaporating front was presented in 0~10 cm soil layer of the furrow ,but in 10~20 cm soil layer of ridge .The soil water in furrow surface diffused directly to the out‐side ,while the evaporation vapor from 10~20 cm soil layer of ridge were adsorbed by 0~10 cm soil ,and the exchange motions of water molecules had occurred before it diffused to the outside .