55
2
Composition of the Major Components of Seawater
2.1
Introduction
Seawater is composed of a number of different components that can be divided into the
following phases:
1. Solids (material that does not pass through a 0.45-μm filter)
a. Particulate organic material (plant detritus)
b. Particulate inorganic material (minerals)
2. Gases
a. Conservative (N 2 , Ar, Xe)
b. Nonconservative (O 2 and CO 2 )
3. Colloids (passes through a 0.45-μm filter but is not dissolved)
a. Organic (complex sugars)
b. Inorganic (iron hydroxides)
4. Dissolved solutes
a. Inorganic solutes
1. Major (>1 ppm)
2. Minor (<1 ppm)
b. Organic solutes
It should be pointed out that the separation of the phase of an element between solid,
colloidal, and dissolved is operational and dependent upon the separation method used.
Figure 2.1 demonstrates how the sizes of some solutes are related to the methods used to
separate the phases. This chapter discusses the various dissolved major components of
seawater. It examines the concentration of the major components in seawater and the processes that can cause them to vary from place to place.
The earliest chemical analysis of seawater was made by Bergman in 1779. Since that time,
many workers have determined one or more elements in various ocean waters. Marcet
in 1819 was the first to suggest that the relative composition of sea salt is nearly constant.
Marcet analyzed water samples from the Arctic, Atlantic, Mediterranean, Black, Baltic,
China, and White Seas. Although his techniques were rather crude and the atomic weights
were only approximately known, his conclusions are correct: “All the species of seawater
contain the same ingredients all over the world, these bearing very nearly the same proportion to each other, so that they differ only as to the total amount of their saline contents”
2
Composition of the Major Components of Seawater
2.1
Introduction
Seawater is composed of a number of different components that can be divided into the
following phases:
1. Solids (material that does not pass through a 0.45-μm filter)
a. Particulate organic material (plant detritus)
b. Particulate inorganic material (minerals)
2. Gases
a. Conservative (N 2 , Ar, Xe)
b. Nonconservative (O 2 and CO 2 )
3. Colloids (passes through a 0.45-μm filter but is not dissolved)
a. Organic (complex sugars)
b. Inorganic (iron hydroxides)
4. Dissolved solutes
a. Inorganic solutes
1. Major (>1 ppm)
2. Minor (<1 ppm)
b. Organic solutes
It should be pointed out that the separation of the phase of an element between solid,
colloidal, and dissolved is operational and dependent upon the separation method used.
Figure 2.1 demonstrates how the sizes of some solutes are related to the methods used to
separate the phases. This chapter discusses the various dissolved major components of
seawater. It examines the concentration of the major components in seawater and the processes that can cause them to vary from place to place.
The earliest chemical analysis of seawater was made by Bergman in 1779. Since that time,
many workers have determined one or more elements in various ocean waters. Marcet
in 1819 was the first to suggest that the relative composition of sea salt is nearly constant.
Marcet analyzed water samples from the Arctic, Atlantic, Mediterranean, Black, Baltic,
China, and White Seas. Although his techniques were rather crude and the atomic weights
were only approximately known, his conclusions are correct: “All the species of seawater
contain the same ingredients all over the world, these bearing very nearly the same proportion to each other, so that they differ only as to the total amount of their saline contents”