Chapter 9
Binding Ability of Inorganic Major Components of
Sea Water towards some Classes of Ligands, Metal
and Organometallic Cations
C. De Stefano . C. Foti . A. Gianguzza . D. Piazzese . S. Sammartano
9.1
Introduction
"Sea water chemical system" can be thought of as a heterogeneous multi-component
solution whose aqueous phase, which also contains particulate matter and colloids, is
in contact with the sediments and the atmosphere (see Millero, this volume). In such a
system, all chemical elements are present as different chemical species in a very wide range
of concentrations, from nmol r 1 to mmol r 1. A possible classification of sea water components, based on the types of substances present (inorganic and organic ions and molecules,
organometallic compounds, colloids, etc.) and on their concentrations, is shown in Table 9.1.
Most biogeochemical processes occur in surface sea water (up to a few hundred
metres in depth) and involve dissolved and particulate organic matter (productivity
and degradation) and nutrients, as well as essential trace metals. These processes are
generally called "open processes:' because they depend on the environmental and
geographical conditions of the seas. This means that the strength of these processes,
as well as the amounts of substances involved ("non conservative components"), is extremely variable. Despite their importance to marine life and their high number, the
total concentration of these components is generally low in aqueous solution (fig r1),
contributing to sea water salinity by less than 0.5%.
The most abundant solutes in sea water are major and minor ions (Table 9.1). These
are present in constant proportions ("conservative components"), because their concentrations are largely controlled by physical processes, such as evaporation/precipitation, by the transportation of water masses and by geological exchange processes
between water and sediments. Taken together, these ions constitute over 99.5% of the
total content of solutes dissolved in sea water, of which the major ions Na +, K+, Ca 2 +,
Mg2+, cr, soi- make up 99.8%. The sodium and chloride ions alone account for 86%.
Due to their abundance, the major ions cause sea water to have very high concentrations of positive and negative charges, which can determine electrostatic interactions
both with each other (internal interactions) and with other acid-base systems present
in the solution (external interactions).
9.2
Artificial Sea Water
Considering the above, it can be stated that an artificial solution containing major and
minor ions (Table 9.1) can usefully represent total sea water salinity and can be used
as a salt ionic medium for thermodynamic studies in sea water. Artificial sea water
has been widely used over the past few decades for two main purposes: (a) as a refer-
Binding Ability of Inorganic Major Components of
Sea Water towards some Classes of Ligands, Metal
and Organometallic Cations
C. De Stefano . C. Foti . A. Gianguzza . D. Piazzese . S. Sammartano
9.1
Introduction
"Sea water chemical system" can be thought of as a heterogeneous multi-component
solution whose aqueous phase, which also contains particulate matter and colloids, is
in contact with the sediments and the atmosphere (see Millero, this volume). In such a
system, all chemical elements are present as different chemical species in a very wide range
of concentrations, from nmol r 1 to mmol r 1. A possible classification of sea water components, based on the types of substances present (inorganic and organic ions and molecules,
organometallic compounds, colloids, etc.) and on their concentrations, is shown in Table 9.1.
Most biogeochemical processes occur in surface sea water (up to a few hundred
metres in depth) and involve dissolved and particulate organic matter (productivity
and degradation) and nutrients, as well as essential trace metals. These processes are
generally called "open processes:' because they depend on the environmental and
geographical conditions of the seas. This means that the strength of these processes,
as well as the amounts of substances involved ("non conservative components"), is extremely variable. Despite their importance to marine life and their high number, the
total concentration of these components is generally low in aqueous solution (fig r1),
contributing to sea water salinity by less than 0.5%.
The most abundant solutes in sea water are major and minor ions (Table 9.1). These
are present in constant proportions ("conservative components"), because their concentrations are largely controlled by physical processes, such as evaporation/precipitation, by the transportation of water masses and by geological exchange processes
between water and sediments. Taken together, these ions constitute over 99.5% of the
total content of solutes dissolved in sea water, of which the major ions Na +, K+, Ca 2 +,
Mg2+, cr, soi- make up 99.8%. The sodium and chloride ions alone account for 86%.
Due to their abundance, the major ions cause sea water to have very high concentrations of positive and negative charges, which can determine electrostatic interactions
both with each other (internal interactions) and with other acid-base systems present
in the solution (external interactions).
9.2
Artificial Sea Water
Considering the above, it can be stated that an artificial solution containing major and
minor ions (Table 9.1) can usefully represent total sea water salinity and can be used
as a salt ionic medium for thermodynamic studies in sea water. Artificial sea water
has been widely used over the past few decades for two main purposes: (a) as a refer-