| 断陷盆地高原面典型岩溶洼地旱季土壤水氢氧同位素时空差异特征 |
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| 引用本文： | 霍伟杰,蒲俊兵,李建鸿,张 陶,王赛男.断陷盆地高原面典型岩溶洼地旱季土壤水氢氧同位素时空差异特征[J].中国岩溶,2019,38(3):307-317. |
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| 作者姓名： | 霍伟杰 蒲俊兵 李建鸿 张 陶 王赛男 |
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| 作者单位： | 1.中国地质科学院岩溶地质研究所/自然资源部、广西岩溶动力学重点实验室，广西 桂林 541004/中国地质大学（北京），北京 100083 |
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| 基金项目： | 国家重点研发计划课题（2016YFC0502501）;国家自然科学基金（41572234）;广西自然科学基金项目（2017GXNSFFA198006） |
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| 摘 要： | 以云南省蒙自断陷盆地东山山区典型岩溶洼地为研究区,通过野外采集土壤样品与实验室测试分析相结合的方法,运用稳定同位素技术研究旱季不同深度土壤水氢氧同位素组成,揭示区内土壤水氢氧同位素时空变化特征,为进一步研究云南断陷盆地山区土壤水分运移机制和当地农业合理利用和管理水资源提供科学依据。结果表明:(1)土壤水δD、δ18O同位素值的变化范围分别为-128.3‰~-27.6‰和-17.5‰~2.5‰,平均值分别为-96.1‰±20.7‰和-12.3‰±3.7‰,降雨转化为土壤水和水分在土壤中重新分布时发生一定程度的氢氧同位素分馏。(2)旱季两个月份土壤水氢氧同位素组成发生变化,4月份土壤水δD、δ18O同位素平均值分别为-86.3‰±23.83‰和-10.6‰±4.3‰,显著高于2月份(δD:-106.1‰±9.5‰;δ18O:-14.1‰±1.6‰)(p<0.05),主要和4月份土壤水的蒸发作用强烈有关。(3)在空间上,坡地与洼地之间土壤水氢氧同位素组成存在差异,2月份坡地与洼地之间土壤水δD、δ18O值差异显著(p<0.05),洼地土壤水δD、δ18O比坡地偏轻;4月份坡地与洼地之间土壤水δD、δ18O值差异不显著(p>0.05)。(4)土壤垂直剖面方向上土壤水δD、δ18O值随着土壤深度的增加而减小,浅层土壤水δ18O和深层土壤水δ18O存在显著差异,2月份浅层土壤水δ18O比深层土壤水δ18O偏正2.8‰,4月份浅层土壤水δ18O比深层土壤水δ18O偏正10.5‰。
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| 关 键 词： | 断陷盆地 土壤水 氢氧同位素 时空差异 大气降雨 蒸发 |
Spatial and temporal variations of soil water δD and δ18O values in dry season in a typical karst depression of a karst graben basin,Yunnan Province,south China |
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| HUO Weijie,PU Junbing,LI Jianhong,ZHANG Tao and WANG Sainan.Spatial and temporal variations of soil water δD and δ18O values in dry season in a typical karst depression of a karst graben basin,Yunnan Province,south China[J].Carsologica Sinica,2019,38(3):307-317. |
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| Authors: | HUO Weijie PU Junbing LI Jianhong ZHANG Tao and WANG Sainan |
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| Institution: | 1.Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamic，MNR＆GZAR，Guilin, Guangxi 541004，China/China University of Geosciences（Beijing）， Beijing 100083, China）2.Institute of Karst Geology,CAGS/Key Laboratory of Karst Dynamic，MNR＆GZAR，Guilin, Guangxi 541004，China |
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| Abstract: | Stable isotope compositions (δD and δ18O) of soil water can be used to reveal some important information about soil hydrology, including rainwater infiltration, evaporation, groundwater recharge and specific flow and transport processes taking place in the soil. In this study, stable hydrogen and oxygen isotope component of soil water in different months and soil depths in Niuerpo karst depression (Dong mountain, Mengzi City, Yunnan Province) were analyzed. The study aimed to revealing the spatial and temporal variation characteristics of soil water in the area and providing a scientific basis for further research of soil water movement mechanism. The results show that the δD and δ18O values range from -128.3‰ to -27.6‰ and -17.5‰ to 2.5‰, with a mean value of -96.1‰±20.7‰ and -12.3‰±3.7‰, respectively. Fractionation of δD and δ18O value of the water possibly occurs to some extent when rainwater infiltrates into the soil and then is redistributed in the soil layers. The mean values of δD and δ18O of soil water in April (-86.3‰±23.8‰ and -10.6‰±4.3‰, respectively) are significant higher than that in February (-106.1‰±9.5‰ and -14.1‰±1.6‰, respectively), which was mainly attributed to the evaporation of the soil water. Spatially, there is a difference in the composition of hydrogen and oxygen isotopes between the soil of slope land and the depression. In February, there is a significant difference in the δD and δ18O value between the slope land and the depression (p<0.05). The soil water δD and δ18O value in the depression were lighter than those in the slope. In April, there is no significant difference in δD and δ18O value of soil water between the slope land and the depression (p>0.05). The soil water δD and δ18O values in the depression are slightly lighter than those in the slope. The soil water δD and δ18O values decrease with the increases of soil depth in vertical profile. There are significant differences between shallow soil water δ18O and deep soil water δ18O. In February, the δ18O value of shallow soil water is 2.8‰ higher than that of deep soil water; in April, the δ18O value of shallow soil water is 10.5‰ higher than that of deep soil water. |
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| Keywords: | karst graben basin soil water hydrogen and oxygen isotope temporal and spatial variation rainfall precipitation evaporation |
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