oa {seacarb}R Documentation

Perturbation of the seawater carbonate system

Description

Describes the various approaches that can be used to alter the seawater carbonate system. Its main purpose is to assist the design of ocean acidification perturbation experiments.

Usage

oa(flag, var1, var2, pCO2f, pCO2s=1e6, S=35, T=25, P=0, 
        Pt=0, Sit=0, k1k2='l', kf='pf', pHscale="T", plot=FALSE)

Arguments

flag select the couple of variables available to describe the initial seawater. The flags which can be used are:
flag = 1 pH and CO2 given
flag = 2 CO2 and HCO3 given
flag = 3 CO2 and CO3 given
flag = 4 CO2 and ALK given
flag = 5 CO2 and DIC given
flag = 6 pH and HCO3 given
flag = 7 pH and CO3 given
flag = 8 pH and ALK given
flag = 9 pH and DIC given
flag = 10 HCO3 and CO3 given
flag = 11 HCO3 and ALK given
flag = 12 HCO3 and DIC given
flag = 13 CO3 and ALK given
flag = 14 CO3 and DIC given
flag = 15 ALK and DIC given
flag = 21 pCO2 and pH given
flag = 22 pCO2 and HCO3 given
flag = 23 pCO2 and CO3 given
flag = 24 pCO2 and ALK given
flag = 25 pCO2 and DIC given
var1 Value of the first variable available to describe the initial seawater, in mol/kg except for pH and for pCO2 in uatm
var2 Value of the second variable available to describe the initial seawater, in mol/kg except for pH
pCO2f pCO2 target value, in uatm
pCO2s pCO2s is the pCO2, in uatm, of the “high-CO2” seawater that will be mixed with “normal seawater”. The default value is 10^6 uatm, that is seawater bubbled with pure CO2 gas and saturated with CO2.
S Salinity, default is 35
T Temperature in degrees Celsius, default is 25
P Hydrostatic pressure in bar (surface = 0), default is 0
Pt Concentration of total phosphate in mol/kg, default is 0
Sit Concentration of total silicate in mol/kg, default is 0
k1k2 "l" for using K1 and K2 from Lueker et al. (2000) and "r" for using K1 and K2 from Roy et al. (1993), default is "l"
kf "pf" for using Kf from Perez and Fraga (1987) and "dg" for using Kf from Dickson and Goyet (1979), default is "pf"
pHscale "T" for the total scale, "F" for the free scale and "SWS" for using the seawater scale, default is "T" (total scale)
plot A plot of the different perturbation methods can be plotted in a DIC vs ALK field with pCO2 isoclines are drawn in the back. Default is false.

Details

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.

Pressure corrections and pH scale

Value

The function returns a list built as follows:

description A table describing in plain English the various ways to reach the target pCO2. Note that if a vector is given in argument only the first value is used.
perturbation Table providing key parameters for the following methods:
CO2 bubbling: high-CO2 air is bubbled in seawater. The first parameter is the value of the pCO2 in the air required to bubble the seawater (in uatm).
SW mixing: mixing of “normal” and “high-CO2” seawater. The fist parameter, “Weight fraction high-CO2 SW” or wf, is the weight fraction of the high-CO2 seawater per kg seawater.
Addition of acid: strong acid is added to seawater. Note that this method is not recommended because it does not closely mimic natural ocean acidification (Gattuso and Lavigne, 2009). The first parameter, H+ (mol/kg), is the amount of H+ that must be added (mol/kg).
Addition of HCO3 and acid: bicarbonate (HCO3) and a strong acid are added. The first parameter, HCO3, is the amount of HCO3 that must be added (mol/kg). The second parameter, H+, is the quantity of H+ that must be added (mol/kg).
Addition of CO3 and acid: carbonate, CO3, and a strong acid are added. The first parameter, HCO3, is the quantity of CO3 that must be added (mol/kg). The second parameter, H+, is the quantity of H+ that must be added (mol/kg).
summary Table summarizing the carbonate chemistry before and after applying each perturbation: pCO2 bubbling, mixing with high-CO2 seawater, addition of strong acid, and addition of bicarbonate/carbonate and strong acid.

Warnings

Author(s)

Heloise Lavigne and Jean-Pierre Gattuso gattuso@obs-vlfr.fr

References

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.

Gattuso J.-P. and Lavigne H., 2009; Technical note: approaches and software tools to investigate the impact of ocean acidification. Biogeosciences 21, 6:2121-2133.

Lueker, T. J. Dickson, A. G. and Keeling, C. D. 2000. Ocean pCO2 calculated from dissolved inorganic carbon, alkalinity, and equations for K1 and K2: validation based on laboratory measurements of CO2 in gas and seawater at equilibrium. Marine Chemistry 70 105-119.

Perez, F. F. and Fraga, F. 1987. Association constant of fluoride and hydrogen ions in seawater. Marine Chemistry 21, 161-168.

Roy, R. N. Roy, L. N. Vogel, K. M. Porter-Moore, C. Pearson, T. Good C. E., Millero F. J. and Campbell D. M., 1993. The dissociation constants of carbonic acid in seawater at salinities 5 to 45 and temperatures 0 to 45oC. Marine Chemistry 44, 249-267.

Schulz K. G., Barcelos e Ramos J., Zeebe R. E. and Riebesell U., 2009. CO2 perturbation experiments: similarities and differences between dissolved inorganic carbon and total alkalinity manipulations. Biogeosciences 6, 2145-2153.

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

See Also

carb, pgas, pmix, ppH, pTA.

Examples

oa(flag=24, var1=384, var2=2325e-6, pCO2s=1e6, pCO2f=793, S=34.3, T=16, 
        P=0, pHscale="T", kf="pf", k1k2="l", plot=TRUE)

[Package seacarb version 2.3.1 Index]