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Chemical Oceanography, 4th Edition
to the upwelling of deep waters, which have higher NTA due to the dissolution of CaCO 3
shells (formanifera and pterpods).
Profiles of TA in the North Atlantic and North Pacific are shown in Figure  7.26. The
surface values of TA in the Pacific are lower than in the Atlantic, while in the deep waters
TA is lower in the Atlantic and higher in the Pacific. The surface differences are due to
the higher salinities of the surface waters in the Atlantic caused by evaporation. If one
normalizes the TA to a constant salinity (S = 35), the results are as expected (Figure 7.27).
The surface values in both oceans are the same, and the NTA in deep waters is higher in
the Pacific than in the Atlantic. The higher NTA in deep waters is related to the dissolution
of CaCO 3 . The deep Pacific alkalinity values are higher than those in the Atlantic because
they are older and have accumulated more CO 3
2– from the dissolution of CaCO 3 .
Sections of TA for the Atlantic and Pacific are not shown since they are similar to the
salinity sections shown in the first chapter. Sections of TA in the major oceans are shown
in Figure 7.28. The distribution of TA is very similar to the salinity distributions that follow the major water masses as shown for salinity in Chapter 1. The values of TA in deep
waters increase from the North Atlantic (2330 μmol kg –1 ) to the North Pacific (2430 μmol
kg –1 ) because of the dissolution of CaCO 3 in the waters.
Latitude
–50 –40 –30 –20 –10 0 10 20 30 40 50 60 70
Latitude
–50 –40 –30 –20 –10 0 10 20 30 40 50 60 70
Latitude
–50 –40 –30 –20 –10 0 10 20 30 40 50 60 70
T (°C)
8
12
16
20
24
28
Salinity
33
34
35
36
37
38
TA (µmol kg
–1
)
2200
2250
2300
2350
2400
2450
2500
Figure 7.22
The temperature, salinity, and total alkalinity (TA) in the Atlantic Ocean.