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| Titel |
A stable isotope study of water movements with typical vegetation cover in the North China Plain |
| VerfasserIn |
Bin Ma, Xing Liang, Shaohua Liu, Menggui Jin, Jing Li |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104139
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| Publikation (Nr.) |
 EGU/EGU2015-3564.pdf |
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| Zusammenfassung |
| The stable isotope 2H and 18O are often used as natural tracers in subsurface water pathways
in semi-arid areas. The stable isotopic compositions in precipitation, soil water and
groundwater were observed to assess the temporal variations in soil water flow at three sites
covered by grass (Carex humili and Carex lanceolata) (site A), poplar (Ponulus hopeiensis)
(site B) and winter wheat (Triticum asetivum) and summer maize (Zea mays) (site C) in the
shallow groundwater area in the North China Plain (NCP) from April 2012 to October 2013.
Precipitation isotopes resulted in a meteoric water line of δ2H =7.6δ18O -3.7 and showed a
typical seasonal variation for δ2H (-98.9 to -13.3) and δ18O (-12.0 to -1.7). The
seasonality in the shallow groundwater was further subdued due to the evaporation and
mixing and diffusional exchange with stored water held in the soil pores within the
unsaturated zone. Shallow groundwater was mainly recharged by precipitation in the
rainy season. Soil water isotope profiles were sampled at depths of 10 cm down to
150 cm every 10 cm for the three sites. The vertical profiles of soil water δ18O
showed large variations in the superficial 10 cm layer under the precipitation input
and evapotranspiration effects. The soil water δ18O decreased and soil moisture
increased with depth (Â70 cm) due to continuously evapotranspiration for the three sites
though that at site B showed more positive δ18O values and smaller soil moisture
than those at site A and C. The signal of individual rainstorm event in the summer
with low δ18O values could be traced down to a depth of 40 cm that mixed with
antecedent mobile soil water and to 120 cm due to a fast and direct preferential
infiltration of the input rainwater that bypassed the upper soil layer at sites B and C.
Keywords: stable isotopes; soil water pathways; groundwater recharge; North China
Plain |
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