README.md

In acgold/compensateR: Temperature and salinity compensation for water quality sensor data

compensateR

An R package used to compensate unprocessed data from environmental sensors for temperature and salinity.

Install compensateR using devtools:

install.packages("devtools")
devtools::install_github("acgold/compensateR")

Dissolved Oxygen

Temperature + salinity compensation and conversion from mg/L to % saturation performed using equations from Garcia and Gordon, 1992. Described and summarized here: https://water.usgs.gov/admin/memo/QW/qw11.03.pdf

Example

temperature <- rnorm(10, mean = 25, sd = 8)
dissolved_oxygen <- rnorm(10, mean = 6, sd = 2)

adj_DO <- DO_adjust(base_temp = 25, temperature = temperature, dissolved_oxygen = dissolved_oxygen)
perc_sat <- DO_adjust_units(temperature = temperature, dissolved_oxygen = adj_DO)

Specific Conductivity & Salinity

Calculation of specific conductance performed using a simple linear equation with 2% difference/degree used by the US EPA and described in Standard Methods:

Specific conductance = conductivity /(1 - ((25-T) * 0.02))

where T = water temperature in ˚C

Salinity is estimated using specific conductivity and the following function from Schemel 2001 as described in the Computation of Salinity section in Wagner et al., 2006.

salinity <- function(specific_conductance){
  sc <- c(specific_conductance)

  R <- sc/53087

  k1 <- 0.0120
  k2 <- -0.2174
  k3 <- 25.3283
  k4 <- 13.7714
  k5 <- -6.4788
  k6 <- 2.5842

  salinity <- k1 + (k2 * (R^(1/2))) + (k3 * R) + (k4 * (R^(3/2))) + (k5 *( R^2)) + (k6 * (R^(5/2)))

  return(salinity)
}

Examples

conductivity <- rnorm(10, 500, sd = 100)
temperature <- rnorm(10, mean = 25, sd = 8)

sc <- sp_conductance(temperature = temperature, conductivity = conductivity)

sal <- salinity(sc)

More Resources

Overview of temperature and salinity compensation: https://www.fondriest.com/environmental-measurements/parameters/water-quality/conductivity-salinity-tds/

References

Fondriest Environmental, Inc. “Conductivity, Salinity and Total Dissolved Solids.” Fundamentals of Environmental Measurements. 3 Mar 2014. Web. URL:https://www.fondriest.com/environmental-measurements/parameters/water-quality/conductivity-salinity-tds/

Garcia, H.E., and Gordon, L.I., 1992, Oxygen solubility in seawater—Better fitting equations: Limnology and Oceanography, vol. 37, no. 6, p. 1307-1312. URL:http://www.jstor.org/stable/pdfplus/2837876.pdf

Standard Methods For the Examination of Water and Wastewater, 2510 CONDUCTIVITY (2017), DOI:10.2105/SMWW.2882.027, URL:https://www.standardmethods.org/doi/full/10.2105/SMWW.2882.027

US EPA, 1982, Method 120.1: Conductance (Specific Conductance, µmhos at 25˚C) by Conductivity Meter, URL:https://www.epa.gov/sites/production/files/2015-08/documents/method_120-1_1982.pdf

Wagner, R.J., Boulger, R.W., Jr., Oblinger, C.J., and Smith, B.A., 2006, Guidelines and standard procedures for continuous water-quality monitors—Station operation, record computation, and data reporting: U.S. Geological Survey Techniques and Methods 1–D3, 51 p. + 8 attachments; accessed August 25, 2021, at http://pubs.water.usgs.gov/tm1d3

acgold/compensateR documentation built on Aug. 30, 2021, 8:08 a.m.