Application of Hydrogen and Oxygen Stable Isotopes Technique in the Water Depletion of Ecosystems
Received date: 2011-03-23
Request revised date: 2011-06-05
Online published: 2012-03-25
Copyright
Stable isotopes of oxygen and hydrogen play an important role in the research on water transport and exchange. The composition of deuterium (D or 2H) and oxygen 18 (18O) in water is very stable, which would not change with time unless fractionation happens. Therefore, they are good fingerprint of water movement. The fractional process of stable isotope is the key for tracing water cycling and transfer. Fractionation leads to the heavy isotopes enrichment of water evaporation vapor. And isotope composition of plant transpiration vapor is similar to the soil water absorbed by the roots except some halophilous plants. Measurement technologies for the isotope composition are mass-spectrometric method and laser method. Water depletion structure was partitioned by the combination of isotopic method and other method like the eddy covariance system. The plant transpiration accounted for about 6%-90% in different ecosystems or for different growth periods. Isotope compositions of different water sources were compared for the judgment of main root uptake layers. The application of hydrogen, oxygen and carbon isotopes in the leaf water-carbon coupling research revealed that 18O was enriched because of the photosynthesis and transpiration. As the composition of carbon dioxide and water, isotope compositions of 18O, 2H and 13C in leaves could also be used to show the change of water use efficiency which was calculated by the carbon accumulation and water depletion. There still existed some problems in the application of this technique like the upscaling and impact factors analysis while some possible improvements were discussed.
ZHANG Yu-cui , SUN Hong-yong , SHEN Yan-jun , QI Yong-qing . Application of Hydrogen and Oxygen Stable Isotopes Technique in the Water Depletion of Ecosystems[J]. SCIENTIA GEOGRAPHICA SINICA, 2012 , 32(3) : 289 -293 . DOI: 10.13249/j.cnki.sgs.2012.03.289
The authors have declared that no competing interests exist.
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