4
Fig. 1.1. The ratio of the concentration of major cations to
the chlorinity in different
oceans
0.6
0.5
0.4
0.3
0.2
0.1
o
Na/CI
0.55
0.35
0.15
-0.05 oJ Atlantic
o Surface
o Deep
I
K/CI
Pacific
r:~: ~
.:"
MgtCI
F. J. Millero
Indian
Ocean
o NatCi
o K/CI
Mg/CI
• Ca/Ci
CalCI
Fig. 1.2. The ratio of the concentration of major cations to the chlorinity in surface and deep waters
which precipitates all the major halides except F-. Average sea water has a chlorinity
of 19.3740/00 (parts per thousand). To be consistent over the years, the silver used in the
titrations on standard sea water (provided for calibrations) has come from the same
bar used originally by Knudsen (1901), who set up the protocol. The relative composition (in grams per chlorinity, g/Cl(o/oo)) of average sea water at 25°C and pH = 8.1 is
given in Table 1.1 (Millero 1996). These values of g/Cl(o/oo) can be used to determine
the stoichiometry of the components of sea water at a given Cl as well as average sea
water having a Cl(%o) = 19.374. The values of the total grams (gT = I,gi)' total moles
(nT = l!2I,ni + nB), total equivalents (eT = l!2I,niZi) and ionic strength (I = 1!2I,niZ7)
can be determined from the values of g/Cl(o/oo) (Table 1.1). This leads to the total molality given by:
mT = 28.903 Cl(%o) / [1000 - 1.8154 Cl(o/oo)]
(1.2)
and total molal ionic strength (I = 1!2I,miZ7) given by:
IT= 35.99 Cl(%o) 1[1000 -1.8154 Cl(%o)]
(1.3)