sr_to_sal: Convert measured Strontium ratio to salinity

In ctdenney/OGFLtools: Several utility functions for use in the OGFL

Convert measured Strontium ratio to salinity

Description

This function calculates salinity from measured Strontium isotope ratio (87Sr/86Sr) using a simple 2 end member mixing model. The function requires the measured sample Sr isotope ratio (87Sr/86Sr), and for each of the two endmembers the Sr isotope ratio (87Sr/86Sr), concentration, and salinity. Default values are based on measurements from the San Francisco Estuary. Values associated with Endmember 1 are sr1, con1, and sal1. Values associated with Endmember 2 are sr2, con2, and sal2. By convention (although not required), endmember 1 is the lower salinity endmember. The default endmember 1 values were collected from the Sacramento river at CDFW station 711 on 2012-03-08. The default endmember 2 values were collected at Muir Beach on 2007-04-23.

Usage

sr_to_sal(sr, sr1 = 0.70576, sr2 = 0.70918, con1 = 95, con2 = 6819, sal1 = 0.11, sal2 = 31.8, sallim_high, sallim_low, fill_high, fill_low)

Arguments

sr	Measured strontium isotopic ratio. Must be given as the ratio of 87Sr/86Sr.
sr1	Strontium ratio of endmember 1 (by default, the Sacramento River value).
sr2	Strontium ratio of endmember 2 (by default, the Pacfic Ocean value).
con1	Concentation of Strontium in endmember 1. Default values are in parts per billion (ppb), but the function will accept and work with any units, as long as they are the same for con1 and con2
con2	Concentration of Strontium in the ocean (or endmember 2).Default values are in parts per billion (ppb), but the function will accept and work with any units, as long as they are the same for con1 and con2
sal1	Salinity of endmember 1 (by default, the Sacramento River value).
sal2	Salinity of the ocean (or endmember 2).
sallim_high	Maximum allowed salinity value. Default value is the higher salinity of the two endmembers
fill_high	what to replace calculated values that exceed the sallim_high value (e.g. "NA" or 7). Must be either "NA" (as a string) or numeric value. Default is "NA".
sallim_low	Minimum allowed salinity value.Default is the lower salinity of the two endmembers.
fill_low	what to replace calculated values that are lower than the sallim_low value (e.g. "NA" or 0.1). Must be either "NA" (as a string) or numeric value. Default is "NA".
suppress.warnings	argument to suppress the warning that some values are outside the boundaries of the sr1 and sr2 values. Default is F and warnings will be displayed. Value of T will hide warnings. Note that, without the warnings, values outside the sallim values will STILL be replaced.

Value

Value returned will be the calculated salinity value unless that calculated value exceeds the bounds set by the user with sallim_high and sallim_low. In those cases, the calculated value will be replaced with the appropriate fill value.

References

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Mixing model adapted from Phillis, Corey C., David J. Ostrach, B. Lynn Ingram, and Peter K. Weber. "Evaluating otolith Sr/Ca as a tool for reconstructing estuarine habitat use." Canadian Journal of Fisheries and Aquatic Sciences 68, no. 2 (2011): 360-373.

Examples

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ctdenney/OGFLtools documentation built on Feb. 8, 2023, 5:47 p.m.