The document discusses the composition of seawater. It notes that seawater is composed primarily of sodium and chloride ions. Other major ions include magnesium, sulfate, and bicarbonate. Seawater also contains minor and trace elements. Gases like nitrogen, oxygen, carbon dioxide, and argon are dissolved in seawater through diffusion and wave action. Salinity measures the dissolved solids in seawater and averages around 35,000 parts per million. Temperature and salinity influence seawater density, with higher salinity and lower temperatures resulting in higher density. The pH of seawater ranges from 7.5 to 8.4. Turbidity is caused by particles that reduce water clarity. Composition

1. THE COMPOSITION OF SEAWATER

2.  Introduction
 The composition of seawater
o Major Ions
o Minor and trace elements
o Addition of gases
 Salinity
 Ocean Density variation
 Temperature
 Potential of Hydrogen ( pH)
 Turbidity
 Photic zone
 Composition of seawater-impacts
 Conclusion
 References

3. only 2.5% of Earth's water
is freshwater - the
amount needed for life to
survive.
Almost all of the
freshwater is locked up in
ice and in the ground.
Only a little more than
1.2% of all freshwater is
surface water, which
serves most of life's
needs.
Most of the surface fresh-
water water is locked up
in ice, and another 20.9%
is found in lakes. Rivers
make up 0.49% of surface
freshwater.

4. Oceans can be divided into three zones:
• Surface zone:
Its extends from the surface to between 50 and 300 meters, making up about 2% of the
ocean´s volume.
• Transition zone:
Generally occurs over about a 1 Km of depth.
• Deep zone:
Its makes 80% of the ocean´s volume.

5. Classification components present in seawater and approximate concentration ran

6. Concentration of the Major Ions (from Pilson, 1998).

8. • Why study trace element
distributions?
1. Many are nutrients and required to
sustain life (e.g. P, N, Fe, Cu)
2. Others are toxic (e.g. Hg)
3. Some are tracers for redox
conditions (Cr, I, Mn, Re, Mo, V, U)
4. Some form economic deposits such
as manganese nodules (e.g. Cu, Co, Ni,
Cd).
5. Some are tracers of pollution (e.g.
Pb, Ag)

9. The ocean-atmosphere, gases are added to seawater by diffusion and wave action. Hence,
seawater contains various dissolved atmospheric gases, chiefly nitrogen, oxygen, argon,
and carbon dioxide.
GASES IN AIR AND DISSOLVED IN SEA WATER AT EQUILIBRIUM WITH AIR

10. • Salinity is the amount of dissolved solids
in seawater.
• Ocean water has salinity that
approximately 35,000 ppm ( 3.5%).
The salinity of seawater is typically about
35‰, about 220 times saltier than
freshwater.
• Based on total salt content the water
classify into:
- Fresh water ( less than 1,000 ppm)
- Slightly saline water (1,000 ppm to 3,000
ppm)
- Moderately saline water ( 3,000 ppm to
10,000 ppm)
- Highly saline water (10,000 ppm to 35,000
ppm)

11. Diagrammatic representation of the most abundant components in a kilogram of
35 ‰ salinity seawater.

12. Ocean Density Variation:
• Density is defined as mass per unit volume
• Seawater density is influenced by two main factors: salinity and temperature
• higher salinity implies higher density. while higher temperatures imply lower density.

13. Temperature:
• The temperature of oceans is very important,
therefor, the change in temperature and
salinity can increase or decrease the density
of ocean waters at the surface.
• The temperature over the surface of the
ocean is highly various, ranging from less than
0°C near the polar to more than 29°C in the
tropic. It depend on many factors, like latitude
and season.
• The surface heated from sunlight, but at
depth most of the oceans is very cold.
• The area in ocean where warm water on the
surface is separated from deep, colder water,
called as thermoclines.
• Thermocline varies in thickness, from about
300 meters to 910 meters. Below the
thermocline, the water cool slowly. Close to
deep-sea floor, the temperature of ocean
between 1° and 4°C.
• The average temperature of all ocean water
about 3.5°C.

14. Potential of Hydrogen ( pH):
• is a measure of the hydrogen ion concentration of a solution
• pH is important properties of seawater. Its reflected in the form of acidity and alkalinity.
Normally pH range from 0 to 14. seawater pH is typically limited to a range between 7.5
to 8.4.
pH and TCO2 profiles at two stations in the North Pacific vs. North Atlantic. Data were collected by Wang’s group

15. Turbidity:
Ocean turbidity is a measure of the
amount of cloudiness or haziness in
seawater caused by individual particles
that are too small to be seen without
magnification. Highly turbid ocean
waters are those with a large number of
scattering particulates in them. In both
highly absorbing and highly scattering
waters, visibility into the water is
reduced. The scattering particles that
cause the water to be turbid can be
composed of many things, including
sediments and phytoplankton.

16. Zone extends from the surface to a depth where enough light still exists.

18. There are many impacts of composition and
properties of seawater such as:
Marine life
Marine mineral resources
Marine sedimentation patterns
Global climatic aspects
Polar ice formation and melting
Composition of seawater-impacts:

19. • 96.5% of earth´s water in the oceans.
• Chloride and sodium has big concentration in composition of seawater.
• Gases are added to seawater by diffusion and wave action.
• Ocean water has salinity that approximately 35,000 ppm ( 3.5%).
• Seawater density is influenced by salinity and temperature, hence, higher
salinity implies higher density. while higher temperatures imply lower density.
• The temperature of oceans decrease with depth. The average temperature of all
ocean water about 3.5°C.
• seawater pH is typically limited to a range between 7.5 to 8.4.
• There are many impacts of composition and properties of seawater such as:
Marine life, Marine mineral resources, Marine sedimentation patterns, Global
climatic aspects, Polar ice formation and melting and etc…..

20. • Alan P. Trujillo and Harold V. Thurman, 2012, Essentials of Oceanography, tenth
edition, Indian edition published by PHI, New Delhi, Pages 129- 157.
• Morris A.W. and J.P. Riley (1966) The bromide/ chlorinity and sulphate/chlorinity ratio
in seawater. Deep-Sea Res., 13, 699-706.
• Riley J.P. and M. Tongudai (1967) The major cation/chlorinity ratios in seawater.
Chem.Geol., 2, 263-269.
• Broecker, W. S. and Peng T. H., 1982, traces in the sea, Eldigio Press, columbia
University, New York, page 690.
• Susan M. Libes, 2009, introduction to marine Biogeochemistry, second edition, Elsevier
Inc, USA, page 42.
• John V. Walther, Essential of Geochemistry, USA, pages 231- 241.
Web sites:
• http://www.waterencyclopedia.com/Re-St/Sea-Water-Gases-in.html
• http://funwithkrill.blogspot.in/2012/09/seawater-chemistry-north-atlantic-vs.html
• http://ocean.stanford.edu/courses/bomc/chem/lecture_05.pdf
• http://water.usgs.gov/edu/earthwherewater.html …… USGS