isotracer (version 1.1.8)

delta2prop: Convert delta notation to proportion of heavy isotope

Description

For details and references about quantities used in expressing isotopic ratios, see:

Usage

delta2prop(x = NULL, Rstandard = NULL)

Value

A vector of same length of x, containing the proportion (numeric between 0 and 1) of heavy isotope based on the delta values and the Rstandard provided.

Arguments

x

Vector of delta values.

Rstandard

String describing the isotopic measurement, e.g. "d15N", "d13C" and used to set automatically Rstandards (see the Section "Ratios for reference standards" for more details). Alternatively, a numeric value to use for Rstandard, e.g. 0.0036765.

Ratios for reference standards

The ratios for reference standards are taken from the Table 2.1 from Fry 2006. Note that the values used for oxygen isotopes are from the standard mean ocean water (SMOW).

Standards recognized by this function are: c("d15N", "d2H", "d13C", "d17O.SMOW", "d18O.SMOW", "d33S", "d34S", "d36S")

Details

- Figure 1 in Coplen, Tyler B. “Guidelines and Recommended Terms for Expression of Stable-Isotope-Ratio and Gas-Ratio Measurement Results.” Rapid Communications in Mass Spectrometry 25, no. 17 (September 15, 2011): 2538–60. https://doi.org/10.1002/rcm.5129.

- Table 2.1 in Fry, Brian. Stable Isotope Ecology. New York: Springer-Verlag, 2006. //www.springer.com/gp/book/9780387305134.

Examples

deltas <- c(78, 5180, 263, 1065, NA, 153, 345)

# Rstandard can be specified with a string for some preset references
prop15N <- delta2prop(deltas, "d15N")
prop13C <- delta2prop(deltas, "d13C")

# Rstandard can also be specified manually for non-preset references
prop15N_manual <- delta2prop(deltas, 0.0036765)
prop13C_manual <- delta2prop(deltas, 0.011180)

# Call delta2prop() to get the detail of available references
delta2prop()