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Chemical Oceanography, 4th Edition
where ΔpH(a) = –2.0 AOU, with the decrease caused by the oxidation of plant material, and
ΔpH(b) = 2.4 ΔCa (where ΔCa is the change in Ca 2+ caused by the dissolution of CaCO 3 ).
7.5.3 Total alkalinity
The total alkalinity (TA) of surface and deep waters was measured extensively during
the WOCE program and more recently as part of the CLIVAR studies. The surface values
of temperature, salinity, and TA for surface waters in the Atlantic and Pacific Oceans are
shown in Figure 7.22 and Figure 7.23, respectively. As is apparent from these figures, the TA
of surface waters shows variations that are similar to salinity. This is shown more clearly
when TA is plotted versus salinity for the North Atlantic (Figure 7.24). This linear behavior
pCO 2 (µatm)
200 400 600 800 1000 1200 1400 1600
Depth (m)
0
1000
2000
3000
4000
5000
N. Atlantic
N. Paciic
Figure 7.18
Depth profiles for the partial pressure of carbon dioxide in the Atlantic and Pacific Oceans.
Latitude
–50 –40 –30 –20 –10 0 10 20 30 40 50 60 70
pH (in situ)
8.00
8.04
8.08
8.12
8.16
8.20
Atlantic
Figure 7.19
The pH of surface waters in the Atlantic Ocean.