How is global meteoric water line calculated?
How is global meteoric water line calculated?
The global linear relationship between the stable isotopic ratios of hydrogen (δ2H) and oxygen (δ18O) in meteoric waters was first documented by Craig (1961) and yielded the global meteoric water line (GMWL), defined as δ2H=8*δ18O+10.
What is meant by meteoric water?
Meteoric water is the water derived from precipitation (snow and rain). This includes water from lakes, rivers, and icemelts, which all originate from precipitation indirectly.
What is isotopic fractionation?
Isotopic fractionation is defined as the relative partitioning of the heavier and lighter isotopes between two coexisting phases in a natural system.
What are the two stable isotopes of oxygen used to measure changes in the hydrologic cycle through time?
The stable isotopes of hydrogen and oxygen have a long history of use in hydrology and paleoclimatology. Two stable isotopes of hydrogen (1H and 2H) and three of oxygen (16O, 17O and 18O) occur naturally in waters and in biological and geological materials.
How do you calculate LMWL?
We propose the use of a rainfall amount weighted LMWL (^2H = a × ^18O + b) for hydrological applications, where the parameters a and b in the line of best fit, yi = axi + b, are obtained by minimising the least squares equation: ‘n p (y – ax – b) i=1-i–i—-i— LS = ‘n i=1 pi where pi is the rainfall (or …
What is D excess?
Deuterium excess (d-excess) is a second-order stable isotope parameter measured in meteoric water to understand both the source of precipitation and the evolution of moisture during transport.
What is the source of meteoric water?
Meteoric water is derived from the atmosphere, precipitating as rain or snow, and participating in the hydrological cycle (q.v.).
Why is isotopic fractionation important?
Isotopic fractionation can be measured by isotope analysis, using isotope-ratio mass spectrometry or cavity ring-down spectroscopy to measure ratios of isotopes, an important tool to understand geochemical and biological systems.
How do you calculate fractionation?
The equilibrium fractionation factor a between liquid and vapor can be defined in two ways, which are mathematical inverses: a = Rl /Rv or a = Rl /Rv, where Rl and Rv are the isotopic ratios of the liquid and vapor, respectively.
How are isotopes measured in water?
The hydrogen isotopes are measured by passing the vaporized water over a hot metal catalyst to obtain hydrogen gas. This is then measured in an IRMS that has been optimized for low mass species; the amount of 2H is obtained from the ratio of the mass 3 and mass 2 peaks.