composition of seawater

composition of seawater

1. THE COMPOSITION OF SEAWATER

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

3. INTRODUCTION 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. INTRODUCTION 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. The Composition of Seawater Classification components present in seawater and approximate concentration range

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

7. Chemical Composition of Seawater

8. Minor and trace elements in seawater: 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. Addition of gases in seawater: 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: 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 c old. 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 TCO 2  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. Photic zone: Zone extends from the surface to a depth where enough light still exists.

17. Light penetrations Vs. depth

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. Conclusion: 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. References: 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