Dew water isotopic ratios and their relationships to ecosystem water pools and fluxes in a cropland and a grassland in China

Oecologia. 2012 Feb;168(2):549-61. doi: 10.1007/s00442-011-2091-0. Epub 2011 Aug 6.


Dew formation has the potential to modulate the spatial and temporal variations of isotopic contents of atmospheric water vapor, oxygen and carbon dioxide. The goal of this paper is to improve our understanding of the isotopic interactions between dew water and ecosystem water pools and fluxes through two field experiments in a wheat/maize cropland and in a short steppe grassland in China. Measurements were made during 94 dew events of the D and (18)O compositions of dew, atmospheric vapor, leaf, xylem and soil water, and the whole ecosystem water flux. Our results demonstrate that the equilibrium fractionation played a dominant role over the kinetic fractionation in controlling the dew water isotopic compositions. A significant correlation between the isotopic compositions of leaf water and dew water suggests a large role of top-down exchange with atmospheric vapor controlling the leaf water turnover at night. According to the isotopic labeling, dew water consisted of a downward flux of water vapor from above the canopy (98%) and upward fluxes originated from soil evaporation and transpiration of the leaves in the lower canopy (2%).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • China
  • Deuterium
  • Ecosystem*
  • Humidity
  • Oxygen Isotopes
  • Plant Leaves
  • Poaceae
  • Seasons
  • Soil
  • Steam
  • Triticum
  • Water / chemistry*
  • Water / metabolism
  • Xylem / chemistry
  • Zea mays


  • Oxygen Isotopes
  • Soil
  • Steam
  • Water
  • Deuterium