Calculates deuterium excess or line-conditioned excess.
dex(HO, form = "dex", MWL = NULL)Returns a copy of HO with an added field(s) “dex” and/or “lcex” containing the calculated values. Deuterium excess is calculated following Dansgaard (1964) as: dex = \(\delta\)2H - 8 * \(\delta\)18O, and lc-excess following Landwehr & Coplen (2006) as lcex = \(\delta\)2H - m * \(\delta\)18O - b, where m and b are the slope and intercept of MWL, respectively.
data.frame. Hydrogen (column 1) and oxygen (column 2) isotope values for 1 or more water samples.
character. Calculate deuterium excess (“dex”), line-conditioned excess (“lcex”), or “both”.
numeric. Vector the first two elements of which contain the meteoric water line slope and intercept (e.g., as created by mwl). The default value (if MWL = NULL) reflects the Global Meteoric Water Line estimated from a global precipitation compilation in Bowen, et al. (2019). Ignored for form = "dex".
Bowen et al. (2019) Isotopes in the water cycle: Regional- to global-Scale patterns and applications. Annual Review of Earth and Planetary Sciences 47 453--479. tools:::Rd_expr_doi("10.1146/annurev-earth-053018-060220").
Dansgaard (1964) Stable isotopes in precipitation. Tellus 16 436--468. tools:::Rd_expr_doi("10.1111/j.2153-3490.1964.tb00181.x").
Landwehr & Coplen (2006) Line-conditioned excess: A new method for characterizing stable hydrogen and oxygen isotope ratios in hydrologic systems. In Isotopes in Environmental Studies, International Atomic Energy Agency, 132--135. http://www-pub.iaea.org/MTCD/publications/PDF/CSP_26_web.pdf.
O = runif(10, -15, -2)
H = O * 8 + 10 + rnorm(10, 0, 6)
d = dex(data.frame(H, O), form = "both")
print(d)
Run the code above in your browser using DataLab