31. Major Constituents
• Most seawater constituents are ions
• e.g. Cl- and Na+
• Six major constituents
32. Major Constituents
• Most seawater constituents are ions
• e.g. Cl- and Na+
• Six major constituents
• Constitute >99% of seawater salinity
33. Major Constituents
• Most seawater constituents are ions
• e.g. Cl- and Na+
• Six major constituents
• Constitute >99% of seawater salinity
• Concentrations of the major constituents
determine the salinity of seawater
48. Range of Salinity
• Salinity is relatively uniform - 35 ppt
• Salinity varies (over a small range)
49. Range of Salinity
• Salinity is relatively uniform - 35 ppt
• Salinity varies (over a small range)
• General range of variation in the open
ocean is 33-37 ppt
50. Range of Salinity
• Salinity is relatively uniform - 35 ppt
• Salinity varies (over a small range)
• General range of variation in the open
ocean is 33-37 ppt
33 ppt - 37 ppt
52. Marcet’s Principle
• Despite small variations in seawater
salinity, the relative proportions of the
major constituents are constant
53. Marcet’s Principle
• Despite small variations in seawater
salinity, the relative proportions of the
major constituents are constant
• Also called the principle of constant
proportions
76. Marcet’s Principle
• Despite small variations in seawater
salinity, the relative proportions of the
major constituents are constant
77. Marcet’s Principle
• Despite small variations in seawater
salinity, the relative proportions of the
major constituents are constant
• The principle of constant proportions
80. Determine Salinity
• Station 3: salinity = x
• To determine the salinity at a location,
oceanographers need to know the
concentrations of the major constituents
81. Determine Salinity
• Station 3: salinity = x
• To determine the salinity at a location,
oceanographers need to know the
concentrations of the major constituents
• Constitute >99% of seawater salinity
82. Determine Salinity
• Station 3: salinity = x
• To determine the salinity at a location,
oceanographers need to know the
concentrations of the major constituents
• Constitute >99% of seawater salinity
• Concentrations of the major constituents
determine the salinity of seawater
90. Determine Salinity
• Only need to measure the concentration
of one major constituent
• Use Marcet’s principle to calculate the
concentrations of the other constituents
91. Determine Salinity
• Only need to measure the concentration
of one major constituent
• Use Marcet’s principle to calculate the
concentrations of the other constituents
• Which major constituent generally is
measured?
92. Determine Salinity
• Only need to measure the concentration
of one major constituent
• Use Marcet’s principle to calculate the
concentrations of the other constituents
• Which major constituent generally is
measured?
• Cl-
115. Determine Salinity
• To determine salinity within 1%, need to
know the concentrations of only the
major constituents
116. Determine Salinity
• To determine salinity within 1%, need to
know the concentrations of only the
major constituents
• Major constituents are >99% of salinity
117. Determine Salinity
• To determine salinity within 1%, need to
know the concentrations of only the
major constituents
• Major constituents are >99% of salinity
• Only have to measure one major
constituents to determine salinity
118. Determine Salinity
• To determine salinity within 1%, need to
know the concentrations of only the
major constituents
• Major constituents are >99% of salinity
• Only have to measure one major
constituents to determine salinity
• Measure one constituent and calculate
the others using Marcet’s principle
119. Determine Salinity
• To determine salinity within 1%, need to
know the concentrations of only the
major constituents
• Major constituents are >99% of salinity
• Only have to measure one major
constituents to determine salinity
• Measure one constituent and calculate
the others using Marcet’s principle
• Generally measure Cl-
123. Conservative Property
• Concentrations of the major constituents are
conservative properties of seawater
• Conservative properties are
1. altered primarily at the ocean’s surface
124. Conservative Property
• Concentrations of the major constituents are
conservative properties of seawater
• Conservative properties are
1. altered primarily at the ocean’s surface
2. not significantly affected by biological activity
126. • Salinity is altered primarily at the ocean’s
surface by
Change Salinity
127. • Salinity is altered primarily at the ocean’s
surface by
1. addition of water (precipitation)
Change Salinity
128. • Salinity is altered primarily at the ocean’s
surface by
1. addition of water (precipitation)
2. removal of water (evaporation)
Change Salinity
129. Explains Marcet’s Principle
Na+
Cl- Cl-
35 ppt
Cl-/Na+ = 1.8
Despite small variations in
seawater salinity, the relative
proportions of the major
constituents are constant
139. • Why is salinity relatively uniform?
Uniformity of Salinity
140. • Why is salinity relatively uniform?
a small open ocean range of 33-37 ppt
Uniformity of Salinity
141. • Why is salinity relatively uniform?
a small open ocean range of 33-37 ppt
• Uniform because the ocean is well mixed
Uniformity of Salinity
142. • Why is salinity relatively uniform?
a small open ocean range of 33-37 ppt
• Uniform because the ocean is well mixed
• To explain how the ocean became well mixed,
oceanographers use the
Uniformity of Salinity
143. • Why is salinity relatively uniform?
a small open ocean range of 33-37 ppt
• Uniform because the ocean is well mixed
• To explain how the ocean became well mixed,
oceanographers use the
long residence times of the major constituents
Uniformity of Salinity
144. • Why is salinity relatively uniform?
a small open ocean range of 33-37 ppt
• Uniform because the ocean is well mixed
• To explain how the ocean became well mixed,
oceanographers use the
long residence times of the major constituents
short mixing time of the ocean
Uniformity of Salinity
145.
146.
147. All of the major constituents
have residence times > 106 yr
156. Ocean Is Well Mixed
• Residence times of the major constituents are
much, much longer than the mixing time
157. Ocean Is Well Mixed
• Residence times of the major constituents are
much, much longer than the mixing time
1,000,000 yr >>> 1,000 yr
158. Ocean Is Well Mixed
• Residence times of the major constituents are
much, much longer than the mixing time
1,000,000 yr >>> 1,000 yr
106 yr >>> 103 yr
159. Ocean Is Well Mixed
• Residence times of the major constituents are
much, much longer than the mixing time
1,000,000 yr >>> 1,000 yr
106 yr >>> 103 yr
• Residence time/mixing time = X
160. Ocean Is Well Mixed
• Residence times of the major constituents are
much, much longer than the mixing time
1,000,000 yr >>> 1,000 yr
106 yr >>> 103 yr
• Residence time/mixing time = X
106 yr/103 yr = 103
161. Ocean Is Well Mixed
• Residence times of the major constituents are
much, much longer than the mixing time
1,000,000 yr >>> 1,000 yr
106 yr >>> 103 yr
• Residence time/mixing time = X
106 yr/103 yr = 103
• In 1,000,000 yr, the ocean mixes itself 1000x
164. Minor Constituents
and Trace Elements
• Minor constituents measured in ppm
• Trace elements measured in ppb or pptr
165. Minor Constituents
and Trace Elements
• Minor constituents measured in ppm
• Trace elements measured in ppb or pptr
• In general,
166. Minor Constituents
and Trace Elements
• Minor constituents measured in ppm
• Trace elements measured in ppb or pptr
• In general,
Marcet’s principle does not apply
167. Minor Constituents
and Trace Elements
• Minor constituents measured in ppm
• Trace elements measured in ppb or pptr
• In general,
Marcet’s principle does not apply
tend to be nonconservative
168. Minor Constituents
and Trace Elements
• Minor constituents measured in ppm
• Trace elements measured in ppb or pptr
• In general,
Marcet’s principle does not apply
tend to be nonconservative
tend to have shorter residence times
187. Gases
• Are N2, O2, and CO2 conservative or
nonconservative?
188. Gases
• Are N2, O2, and CO2 conservative or
nonconservative?
• N2 is conservative
189. Gases
• Are N2, O2, and CO2 conservative or
nonconservative?
• N2 is conservative
• O2 is nonconservative
190. Gases
• Are N2, O2, and CO2 conservative or
nonconservative?
• N2 is conservative
• O2 is nonconservative
• CO2 is nonconservative
191. Gases
• Are N2, O2, and CO2 conservative or
nonconservative?
• N2 is conservative
• O2 is nonconservative
• CO2 is nonconservative
Both O2 and CO2 are strongly affected
by biological activity
192. Gases
• Are N2, O2, and CO2 conservative or
nonconservative?
• N2 is conservative
• O2 is nonconservative
• CO2 is nonconservative
Both O2 and CO2 are strongly affected
by biological activity
The concentrations of O2 and CO2 are
altered below the ocean’s surface
