Global meteoric water line

Fig. 2.4 Global relationship between monthly means of 5D and in precipitation, derived for all stations of the IAEA global network. Line indicates the global meteoric water line (MWL) (after Rozanski et al. 1993)...

The imprint of local conditions can also be seen at other coastal and continental stations. The examples in Table 3.1 demonstrate that varying influences of different sources of vapor with different isotope characteristics, different air mass trajectories, or evaporation and isotope exchange processes below the cloud base, may often lead to much more complex relationships at the local level between 8D and 8 0 than suggested for the regional or continental scale by the global Meteoric Water Line equation. 

This equation describes the linear distribution of data points on a plot of 8D versus 8lsO that is commonly referred to as the global meteoric-water line (GMWL). The zero intercept for this line, defined as the deuterium excess... 

Global Meteoric Water Line A line on the plane formed when the 5 0 and... 

Meteoric water line Linear relationship between and in precipitation that occurs due to equilibrium fractionation effects during the condensation of moisture. This is generally described by the equation = 8 5 0 -t- 10, known as the Global Meteoric Water Line. 

Clay minerals in soils typically have hydrogen and isotopic compositions that p lel the meteoric water line, so much so that in a graph of 5D against the array mapped out by such determination is called the clay line (e.g., the kaolinite line of Fig. 8). The clay lines are sub-parallel on a global scale to the meteoric water line. In regions where the minerals are growing in a system open to fluid flow and connected to the surface, the minerals form in isotopic equilibrium with the surface fluid hence their SD and 3 0 values parallel the meteoric water hne. These systems behave as if the mole fraction of water approaches 1. 

Figure 11 Isotopic compositions of oil-field waters from several basins in North America. Original lines from Cla3fton et al. (1966), CHitchon and Friedman, (1969), and CKharaka et al. 0973, C1979). Note that except for Gulf Coast II, the isotope lines intersect the Global Meteoric Line (Craig, 1961) at points with isotope values of present-day meteoric water (Kharaka and Thordsen, 1992).

Figure 19 6 H versus 6 0 aKr values of reverse osmosis desalted seawater and the global meteoric waterline (Craig, 1961). The anthropogenic line lies on a possible mixing relationship between natural waters along the meteoric waterline (arrow) and the desalted seawater. Future formation of a large volume of desalted seawater expects to cause infiltration (e.g., leakage, reuse) of freshwater with high S H and 6 0 values relative to natural replenishment.

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