speciation {seacarb}

ionic forms as a function of pH

Description

Estimates the concentration of the various ionic forms of a molecule as a function of pH

Usage

speciation(K1=K1(), K2=NULL, K3=NULL, pH, conc=1)

Arguments

K1

First dissociation constant

K2

Second dissociation constant, default is NULL

K3

Third dissociation constant, default is NULL

pH

pH value, default is 8

conc

concentration of molecule in mol/kg, default is 1 mol/kg

Value

The function returns a data frame containing the following concentrations (in mol/kg if conc is given in mol/kg):

C1

ionic form 1, univalent, bivalent and trivalent molecules

C2

ionic form 2, univalent, bivalent and trivalent molecules

C3

ionic form 3, bivalent and trivalent molecules

C4

ionic form 4, trivalent molecules

Author(s)

Karline Soetaert [e-mail]

References

Zeebe R. E. and Wolf-Gladrow D. A., 2001 CO2 in seawater: equilibrium, kinetics, isotopes. Amsterdam: Elsevier, 346 pp.

See Also

bjerrum.

Examples

## Speciation of divalent species; example to estimate the various ionic forms
## of dissolved inorganic carbon  (DIC = 0.0021 mol/kg) at a salinity of 35,
## a temperature of 25oC and an hydrostatic pressure of 0:
spec <- speciation (K1(35, 25, 0), K2(35, 25, 0), pH=8, conc=0.0021)
## where (spec\$C1=[CO2], spec\$C2=[HCO3-], spec\$C3=[CO3--])

## Speciation of trivalent species (e.g.,  H3PO4, H2PO4-, HPO4--, PO4---)
speciation(K1p(), K2p(), K3p(), conc=0.001)

## Effect of temperature on pCO2 - Figure 1.4.18 of Zeebe and Wolf-Gladrow (2001)
Tseq <- seq(0, 30, by=0.5)
pHseq <- carb(flag=15, var1=2300e-6, var2=1900e-6, S=35, T=Tseq, P=0)$pH
CO2  <- speciation(K1(T=Tseq), K2(T=Tseq), conc=1900, pH=pHseq)$C1
pCO2 <- CO2/K0(T=Tseq)
plot(Tseq, pCO2, xlab="Temperature (oC)", ylab="pCO2 (uatm)", type="l", 
	main="effect of temperature on pCO2")
legend("topleft", c(expression(sum(CO[2])==1900~umol~kg^"-1"), 
	expression(TA==2300~umol~kg^"-1")))