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| 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 |
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