seacarb (version 3.3.3)

pHconv: Conversion of pH

Description

Converts pH from one scale to another one chosen between the total scale, the free scale and the seawater scale

Usage

pHconv(flag=1, pH=8.10, S=35, T=25, P=0, ks="d")

Value

The function returns the values of pH converted

Arguments

flag

choice of the type of conversion : flag=1: seawater scale to total scale flag=2: free scale to total scale flag=3: total scale to seawater scale flag=4: total scale to free scale flag=5: seawater scale to free scale flag=6: free scale to seawater scale default is flag=1

pH

Enter the value of pH which need to be converted, default is 8.100

S

Salinity, default is 35

T

Temperature in degrees Celsius, default is 25oC

P

Hydrostatic pressure in bar (surface = 0), default is 0

ks

"d" for using Ks from Dickon (1990), "k" for using Ks from Khoo et al. (1977), default is "d"

Author

Heloise Lavigne and Jean-Pierre Gattuso

Details

The Dickson (1990) constant is recommended by the Guide to Best Practices for Ocean CO2 Measurements (2007). It is critical to consider that each formulation is valid in specific ranges of temperature and salinity:

• Dickson (1990): S ranging between 5 and 45 and T ranging between 0 and 45oC.

• Khoo et al. (1977): S ranging between 20 and 45 and T ranging between 5 and 40oC.

The arguments can be given as a unique number or as vectors. If the lengths of the vectors are different, the longer vector is retained and only the first value of the other vectors is used. It is recommended to use either vectors with the same dimension or one vector for one argument and numbers for the other arguments.

References

Dickson A.G. and F.J. Millero, 1987 A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media. Deep-Sea Research 34:1733-1743.

Dickson A. G., 1990 Standard potential of the reaction: AgCI(s) + 1/2H2(g) = Ag(s) + HCI(aq), and the standard acidity constant of the ion HSO4 in synthetic sea water from 273.15 to 318.15 K. Journal of Chemical Thermodynamics 22, 113-127.

Dickson A. G., Sabine C. L. and Christian J. R., 2007 Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 1-191.

Khoo H. K., Ramette R. W., Culberson C. H. and Bates R. G., 1977 Determination of Hydrogen Ion Concentration in Seawater from 5 to 40oC: Standard Potentials at Salinities from 20 to 45. Analytical Chemistry 49, 29-34.

See Also

kconv.

Examples

##To convert pH=8.10 from the seawater scale to the total scale
##at salinity=35, temperature=25oC and atmospheric pressure:

  pHc <- pHconv(flag=1, pH=8.10, S=35, T=25, P=0, ks="d")

##note that pHc is the value of the pH converted in total scale

## By using vectors
## to convert the pH values : 8, 8.05, 8.10, 8.15, 8.20 
## from the free to the total scale

pH <- c(8, 8.05, 8.10, 8.15, 8.20)
pHc <- pHconv(flag=2, pH=pH, S=35, T=25, P=0, ks="d")

## note that pHc is a vector containing the value of the pH converted 
## to the total scale