| 引用本文: | 王欢欢,司炳成,李敏.黄土塬区深剖面土壤水氢氧同位素分布特征[J].灌溉排水学报,2018,37(12):53-59. |
| WANG Huanhuan,SI Bingcheng,LI Min.黄土塬区深剖面土壤水氢氧同位素分布特征[J].灌溉排水学报,2018,37(12):53-59. |
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| 摘要: |
| 【目的】揭示黄土塬区深剖面土壤水的氢氧同位素（δ2H、δ18O）分布特征。【方法】于2015年8月采用土芯钻探的方式以20 cm为采样间隔，在长武塬采取98 m（其地下水埋深为95 m）深剖面原状土样。根据测定的土壤水δ2H和δ18O值，将剖面分为浅层（0～10 m）、深层（10～84 m）、过渡层（84～95 m）和地下水层（95～98 m）4层，并采用经典统计学方法分析了整个剖面土壤水氢氧稳定同位素的变异特征。【结果】δ2H在浅层、深层、过渡层和地下水层的平均值分别为-78.6‰、-75.2‰、-74.6‰、-76.5‰，δ18O在相应4层的平均值分别为-10.9‰、-9.9‰、-10.2‰、10.4‰，δ2H和δ18O均在10 m以上的浅层最为贫化。δ2H在浅层、深层、过渡层和地下水层的标准差分别为11.8‰、2.6‰、1.4‰、1.2‰，δ18O在相应4层的标准差SD分别为1.6‰、0.5‰、0.3‰、0.3‰。δ2H和δ18O值在浅层波动较大，变异系数>10%，属于中等变异；而10 m以下相对稳定，变异系数Cv＜10%，属于弱变异；变异系数随深度的增加而逐渐减小。δ2H和δ18O的标准差均随深度增加逐渐减小。【结论】对于以活塞流补给为主的深厚黄土高原地区，深层土壤水氢氧同位素在剖面的变异较小，因此，可利用氢氧同位素趋于稳定的上层土壤水代替深层土壤水来进行地下水补给的研究。 |
| 关键词: 黄土塬； 土壤水； 稳定同位素； 垂直变异 |
| DOI：10.13522/j.cnki.ggps.20180195 |
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| Distribution of Hydrogen and Oxygen Isotopes Along Deep Soil Profiles in a Loess Tableland |
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WANG Huanhuan, SI Bingcheng, LI Min
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College of Water Resources and Architectural Engineering, Northwest A&F Universiry, Yangling 712100, China
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| Abstract: |
| 【Objective】 Stable isotopes have been increasingly used as a tracer to track the movement and origin of water in soil, and the objective of this paper is to investigate the distribution of hydrogen and oxygen isotope along deep soil profiles in a loess plateau. 【Method】 Undisturbed soil samples were taken from soil surface up to groundwater table at 98 m of depth using a drill truck in a loess tableland at Changwu in August 2015. The hydrogen and oxygen isotopes in each sample were measured. We divided the soil profile into four layers: 0~10 m, 10~84 m, 84~95 m and saturated 95~98 m layer. Variability of the isotopes along the soil profiles were statistically analyzed. 【Result】 The average isotope in the four layer were -78.6‰, -75.2‰, -74.7‰ and -76.5‰ for δ2H; and -10.9‰, -9.9‰, -10.2‰ and 10.4‰ for δ18O, respectively; both isotopes were more depleted in the shallow layer. The standard deviation of the isotopes in the four layers was 11.8‰, 2.6‰, 1.4‰, 1.2‰ for δ2H; and 1.6‰, 0.5‰, 0.3‰, 0.3‰ for δ18O. Both isotopes varied more widely in the 0~10 m layer with a coefficient of variation >10%. The isotopes were relatively stable in other layers with their Cv <10%. Both Cv and SD of the two isotopes decreased along the soil profile.【Conclusion】The variation of the isotopes in deep soil is relatively small, suggesting that they were less impact by environment. Therefore, we can use the isotopes measured from the top soil in study of groundwater recharge by rainfall in the loess plateau. |
| Key words: loess tableland; soil water; stable isotope; vertical variability |
