18
F. J. Millero
similar to those of sea salt and the concentrations of added solutes are low (Poisson
et al. 1980; Millero 1984).
More recently Millero (2000b) has shown that empirical relationships can also be
used to fit the experimental measurements:
!!p = 10.2 + 43.9 !!TC02
«(J"= 4-2 ppm)
(1.17)
!!p = 6.0 + 112 !!TA
«(J" = 4.4 ppm)
(1.18)
!!p = 1.9 + 100.5 !!Si02
«(J"= 4.1 ppm)
(1.19)
!!p = 1.1 + 396 !!N03
«(J" = 4.1 ppm)
(1.20 )
The intercept is close to zero except for TA and TC02, which is due to the difference
in the surface values in the Atlantic and Pacific oceans. The individual slopes are larger
than the theoretical values, because they include the changes due to all the constituents in the solution. Since nutrient data are more available than carbonate data, the
equations using Si0 2 and N0 3 may be more useful. The changes in the density of estuarine waters may be different because of changes in the input of various chemicals
from a given river (Poisson et al.1980, 1981; Millero 1984) and the precipitation of minerals such as CaC0 3 •
1.2
Modelling the Physical Properties of Natural Waters
The ionic interactions in a mixed electrolyte solution like sea water can affect the physical properties (density, heat capacity, etc.) of natural waters. Since the composition of
natural waters can be quite different, it is useful to have models that can be used to
describe how the ionic components affect the physical properties. This requires knowledge of ionic interactions in the solutions of interest. Over the years, a great deal of
progress has been made in interpreting and modelling the physico-chemical properties of mixed electrolyte solutions (Millero 2001). This has led to the development of
models that can be used to estimate the properties of natural waters of known composition. These models consider the changes that occur due to ion-water interactions
in dilute solutions and the resultant ion-ion interactions as one moves to more concentrated solutions. The ion-water interactions can be examined using the following
models:
1. Continuum Model
2. Ion-Dipole Model
3. Ion Quadrupole Model
4. Ion-Water Structure Model
5. Hydration Model
The continuum model examines the interactions between an ion in a continuous
dielectric medium. This can be represented by the transfer of an ion from a vacuum
F. J. Millero
similar to those of sea salt and the concentrations of added solutes are low (Poisson
et al. 1980; Millero 1984).
More recently Millero (2000b) has shown that empirical relationships can also be
used to fit the experimental measurements:
!!p = 10.2 + 43.9 !!TC02
«(J"= 4-2 ppm)
(1.17)
!!p = 6.0 + 112 !!TA
«(J" = 4.4 ppm)
(1.18)
!!p = 1.9 + 100.5 !!Si02
«(J"= 4.1 ppm)
(1.19)
!!p = 1.1 + 396 !!N03
«(J" = 4.1 ppm)
(1.20 )
The intercept is close to zero except for TA and TC02, which is due to the difference
in the surface values in the Atlantic and Pacific oceans. The individual slopes are larger
than the theoretical values, because they include the changes due to all the constituents in the solution. Since nutrient data are more available than carbonate data, the
equations using Si0 2 and N0 3 may be more useful. The changes in the density of estuarine waters may be different because of changes in the input of various chemicals
from a given river (Poisson et al.1980, 1981; Millero 1984) and the precipitation of minerals such as CaC0 3 •
1.2
Modelling the Physical Properties of Natural Waters
The ionic interactions in a mixed electrolyte solution like sea water can affect the physical properties (density, heat capacity, etc.) of natural waters. Since the composition of
natural waters can be quite different, it is useful to have models that can be used to
describe how the ionic components affect the physical properties. This requires knowledge of ionic interactions in the solutions of interest. Over the years, a great deal of
progress has been made in interpreting and modelling the physico-chemical properties of mixed electrolyte solutions (Millero 2001). This has led to the development of
models that can be used to estimate the properties of natural waters of known composition. These models consider the changes that occur due to ion-water interactions
in dilute solutions and the resultant ion-ion interactions as one moves to more concentrated solutions. The ion-water interactions can be examined using the following
models:
1. Continuum Model
2. Ion-Dipole Model
3. Ion Quadrupole Model
4. Ion-Water Structure Model
5. Hydration Model
The continuum model examines the interactions between an ion in a continuous
dielectric medium. This can be represented by the transfer of an ion from a vacuum