The δ18O and δ2H showed significant
correlations in plant water, precipitation, and soil water during the
study period (Figure 5). The local
meteoric water line (LMWL) was described by equation,
δ2H =7.89 × δ18O +17.79
(R2 = 0.97; p < 0.05) , its slope was
smaller than the global meteoric water line (GMWL),
δ2H = 8.17 × δ18O + 10.35; (Rozanski
et al., 1993), indicating that evaporation is a main reason of arid
climate and kinetic fractionation in the research sites. The linear
relationships of δ18O and δ2H in
soil water were significantly indicated that the different evaporation
effect between shrub and grassland sites. Additionally, their slopes and
intercepts at the two sites were smaller than those of the LMWL, for the
ongoing evaporation influence soil water (Yang&Fu, 2017). Moreover,
Soil water, plant water and LMWL laid at an angle on the both sites,
indicating that these water types contained water that had been recycled
through
terrestrial evaporation and precipitation.