kconv {seacarb}

Conversion factors to change the pH scale of dissociation constants

Description

Conversion factors from the total scale to the free and seawater scales

Usage

kconv(S=35, T=25, P=0, kf, Ks, Kff, warn="y")

Arguments

S

Salinity, default is 35

T

Temperature in degrees Celsius, default is 25oC

P

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

kf

"pf" for using Kf from Perez and Fraga (1987) and "dg" for using Kf from Dickson and Riley (1979 in Dickson and Goyet, 1994); if the fonction Kf was used previously, the default value is the value given for the argument kf in the fonction Kf. If the Kf function was not used previously, the default value is "pf", except if T is outside the range 9 to 33oC or of S is outside the range 10 to 40. In these cases, the default is "dg".

Ks

Stability constant of hydrogen sulfate (mol/kg) at given S, T and P, optional; if not given, it will be computed, if given, it allows for speed optimisation

Kff

Stability constant of hydrogen fluoride (mol/kg) on free pH scale at given S, T and P, optional; if not given, it will be computed, if given, it allows for speed optimisation and kf parameter is then ignored

warn

"y" to show warnings when T or S go beyond the valid range for constants; "n" to supress warnings. The default is "y".

Details

It is critical to consider that each formulation is valid in specific ranges of temperature and salinity:

• Perez and Fraga (1987): S ranging between 10 and 40 and T ranging between 9 and 33oC.

• Dickson and Riley (1979 in Dickson and Goyet, 1994): S ranging between 0 and 45 and T ranging between 0 and 45oC.

Note that kconv may be called in many functions (i.e. K1, K2, K1p, K2p, K3p, Kw, Ksi, K2si, etc...) without user controls it. To force a particular formulation for Kf, it is recommended to call kconv() first then pass the resulting conversion factors to these functions.

Value

The function returns a list with 6 conversion factors :

ktotal2SWS

to convert from the total scale to seawater scale

ktotal2free

to convert from the total scale to the free scale

kfree2SWS

to convert from the free scale to the seawater scale

kfree2total

to convert from the free scale to total scale

kSWS2total

to convert from the seawater scale to the total scale

kSWS2free

to convert from the seawater scale to the free scale

Author(s)

Karline Soetaert [e-mail]

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.

See Also

pHconv.

Examples

##To convert dissociation constants from the total scale to the free scale
## (at salinity=35, temperature=25oC and atmospheric pressure):
kconv(35,25,0)
conv <- kconv()
 c(K1_total=K1(),K1_SWS=K1()*conv$ktotal2SWS,K1_free=K1()*conv$ktotal2free)