Pcorrect {seacarb}

Pressure correction of equilibrium constants

Description

Computes the pressure correction of the equilibrium constants

Usage

Pcorrect(Kvalue, Ktype, T=25, S=35, P=0, pHscale="T", 
  kconv2ScaleP0="x", kconv2Scale="x", warn="y")

Arguments

Kvalue

Value of the constant at P=0 (hydrostatic pressure in bar, surface = 0)

Ktype

Name of the constant,

• K1 First dissociation constant of carbonic acid (mol/kg)

• K2 Second dissociation constant of carbonic acid (mol/kg)

• Kb Dissociation constant of boric acid (mol/kg)

• Kw Ion product of water (mol2/kg2)

• Ks Stability constant of hydrogen sulfate (mol/kg)

• Kf Stability constant of hydrogen fluoride (mol/kg)

• Kspc Solubility product of calcite (mol/kg)

• Kspa Solubility product of aragonite (mol/kg)

• K1p First dissociation constant of phosphoric acid (mol/kg)

• K2p Second dissociation constant of phosphoric acid (mol/kg)

• K3p Third dissociation constant of phosphoric acid (mol/kg)

• Khs Dissociation constant of hydrogen sufide(mol/kg)

• Kn Dissociation constant of ammonium (mol/kg)

• Ksi Dissociation constant of Si(OH)4 (mol/kg)

• K2si Second dissociation constant of Si(OH)4 (mol/kg)

T

Temperature in degrees Celsius, default is 25oC

S

Salinity, default is 35

P

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

pHscale

pHscale of the constant given in Kvalue

kconv2ScaleP0

Conversion factor from the pH scale selected to the SWS (or free for Kf) scale at pressure zero. It is advised to use default value "x", in which case it is computed when required. (may slow down the computation)

kconv2Scale

Conversion factor from the pH scale selected to the SWS (or free for Kf) scale at the hydrostatic pressure value indicated. It is advised to use default value "x", in which case it is computed when required. (may slow down the computation)

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

• The pressure correction is applied on the seawater scale for K1, K2, K1p, K2p, K3p, Kb, Khs, Kn, Ksi, K2si and Kw. Hence the K value is first converted on the seawater scale if needed. After pressure correction, the constant is converted back to the initial pH scale.

• The pressure correction is applied on the free scale for Kf.

• There is no issue of pH scale for Ks, Kspa and Kspc.

Value

The equilibrium constant given in argument but after pressure correction

Author(s)

Heloise Lavigne and Jean-Pierre Gattuso [e-mail]

References

Millero F. J., 1995 Thermodynamics of the carbon dioxide system in the oceans. Geochimica et Cosmochimica Acta 59 661-677.

See Also

Pcoeffs

Examples

k10 <- K1(T=25, P=0, S=35)
Pcorrect(Kvalue=k10, Ktype="K1", P=300, T=25, S=35, pHscale="T")