281
The Carbonate System
The changes in Ca 2+ are given by
ΔCa = 0.463ΔTA + 0.074ΔTCO 2 = 0.5ΔTA + 0.53ΔNO 3
(7.120)
This equation was first used by Chen (1978) to predict changes in Ca 2+ as a function of
depth in the Pacific that agree very well with the measured values. The changes in inorganic carbon to organic carbon are given by
Inorg C/ Org C = x/106y = 16ΔCa/106ΔNO 3 = (8TA + 8.5ΔNO 3 )/106ΔNO 3 (7.121)
This equation has also been shown by Chen to predict reasonable ratios of inorganic C to
organic C in ocean waters.
If one uses these equations (Brewer, 1978; Chen and Millero, 1979) to examine the
changes in TCO 2 in old deep waters and younger waters, it is possible to make an estimate of the changes caused by the increase of CO 2 in the atmosphere from the burning
of fossil fuels. The estimated increases (≈260 ± 20 ppm for preindustrial values) are in
reasonable agreement with the values (280 ppm) obtained from ice cores (see Figure 5.21).
More will be said about estimating the penetration of fossil fuel into the oceans further
in this chapter.
7.5 Distribution of Carbonate Species
The distribution of the various components of the CO 2 system in the oceans has been
studied by many workers. Skirrow (1975) reviewed much of the earlier work. The earlier 1970s studies of the carbonate system during the GEOSEC (Geochemical Oceans
Sections Study) program yielded the first global look at the CO 2 system. The more recent
JGOFS (Joint Global Ocean Flux Study) CO 2 measurements made in the 1990s as part
of the WOCE (World Ocean Circulation Experiment) hydrographic program yielded a
much more reliable and global picture of the CO 2 system that will serve as a benchmark
for the future. These results are available on the Web (http://cdiac.esd.ornl.gov). Over
the last 10 yr repeat measurements of the oceans have and are still being studied as
part of the Climate Variability and Predictability (CLIVAR) program. These results are
discussed elsewhere in this chapter. In this section, we discuss the distribution of the
CO 2 parameters.
7.5.1 pCO 2
Unfortunately, no historical data of sufficient accuracy are available for pCO 2 in surface
waters of the oceans over time as in the atmosphere. An earlier comparison of the increase
from 1957 to 1980 (Takahashi, Lamont Doherty Earth Observatory) is shown in Figure 7.11.
Recent measurements at the time series stations were shown in this chapter (Figure 7.17).
The repeat measurements over the last 20 yr give a hint of present changes in pCO 2 of surface waters. The most reliable recent measurements of pCO 2 as a function of time to 2007
are the results from the Bermuda and Hawaii Time Series stations, discussed elsewhere in
this chapter. The measured increase in the surface waters appears to track the values in the
atmosphere (2 ppm yr –1 ). The changes in pCO 2 in surface waters can be caused by
The Carbonate System
The changes in Ca 2+ are given by
ΔCa = 0.463ΔTA + 0.074ΔTCO 2 = 0.5ΔTA + 0.53ΔNO 3
(7.120)
This equation was first used by Chen (1978) to predict changes in Ca 2+ as a function of
depth in the Pacific that agree very well with the measured values. The changes in inorganic carbon to organic carbon are given by
Inorg C/ Org C = x/106y = 16ΔCa/106ΔNO 3 = (8TA + 8.5ΔNO 3 )/106ΔNO 3 (7.121)
This equation has also been shown by Chen to predict reasonable ratios of inorganic C to
organic C in ocean waters.
If one uses these equations (Brewer, 1978; Chen and Millero, 1979) to examine the
changes in TCO 2 in old deep waters and younger waters, it is possible to make an estimate of the changes caused by the increase of CO 2 in the atmosphere from the burning
of fossil fuels. The estimated increases (≈260 ± 20 ppm for preindustrial values) are in
reasonable agreement with the values (280 ppm) obtained from ice cores (see Figure 5.21).
More will be said about estimating the penetration of fossil fuel into the oceans further
in this chapter.
7.5 Distribution of Carbonate Species
The distribution of the various components of the CO 2 system in the oceans has been
studied by many workers. Skirrow (1975) reviewed much of the earlier work. The earlier 1970s studies of the carbonate system during the GEOSEC (Geochemical Oceans
Sections Study) program yielded the first global look at the CO 2 system. The more recent
JGOFS (Joint Global Ocean Flux Study) CO 2 measurements made in the 1990s as part
of the WOCE (World Ocean Circulation Experiment) hydrographic program yielded a
much more reliable and global picture of the CO 2 system that will serve as a benchmark
for the future. These results are available on the Web (http://cdiac.esd.ornl.gov). Over
the last 10 yr repeat measurements of the oceans have and are still being studied as
part of the Climate Variability and Predictability (CLIVAR) program. These results are
discussed elsewhere in this chapter. In this section, we discuss the distribution of the
CO 2 parameters.
7.5.1 pCO 2
Unfortunately, no historical data of sufficient accuracy are available for pCO 2 in surface
waters of the oceans over time as in the atmosphere. An earlier comparison of the increase
from 1957 to 1980 (Takahashi, Lamont Doherty Earth Observatory) is shown in Figure 7.11.
Recent measurements at the time series stations were shown in this chapter (Figure 7.17).
The repeat measurements over the last 20 yr give a hint of present changes in pCO 2 of surface waters. The most reliable recent measurements of pCO 2 as a function of time to 2007
are the results from the Bermuda and Hawaii Time Series stations, discussed elsewhere in
this chapter. The measured increase in the surface waters appears to track the values in the
atmosphere (2 ppm yr –1 ). The changes in pCO 2 in surface waters can be caused by