5. Salinity

Main Menu	5. Salinity and its Variability
The Briny Deep Menu 1. Introduction 2. Salt in Seawater? 3. Ions of Salt 4. Source of the Salt? 5. Salinity Variability 6.Salinity & Precipitation 7. Salinity Summary 8. Calculating Salinity 9. Ocean Temperature 10. Solar Radiation 11. Properties 12. Light Penetration 13. Temperature 14. Thermocline 15. Density 16. Layering	Hannes Grobe, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany; SVG version by Stefan Majewsky As mentioned previously, seawater is a weak, complex solution -- weak -- meaning that is highly diluted by a solvent (water) and complex because it contains at 92 different naturally occurring chemical elements -- the most common of which are listed in the table to the left .
	More elements will likely be found in the future as measuring techniques improve through advances in technology. Besides the water itself (H₂O), here is a list of the principal chemical constituents in seawater, with their chemical symbol, and their relative The diagram at the upper left shows the principal constituents and their concentrations in a sample of sea water with a salinity of 3.5% or 35 ^o/oo (parts per thousand). Chloride ion (Cl^-) -- 55% Sodium (Na⁺) -- 30.6% Sulfate (SO4^-2) -- 7.7% Magnesium (Mg ⁺²) -- 3.7% Calcium (Ca⁺²) -- 1.2% Potassium (K⁺) - 1.1% And a small amount (0.7%) of other stuff.......... Oceanographers report salinity (total salt content) and the concentrations of individual chemical constituents in sea water in parts per thousand (also called parts per mil), for which the symbol ^o/oo is used. Remember that % is the symbol for percent or parts per hundred -- divide % by ten or add another zero in the denominator and you have parts per thousand. Thus, a salinity value of 35^o/oo means 35 parts of dissolved salt per 1,000 parts of sea water. Similarly, a sodium (Na⁺) concentration of 10 ^o/oo means 10 pounds of sodium per 1,000 pounds of water. The salinity of sea water exhibits a variation around an average value of 35.5 ^o/oo in the world's oceans depending on the balance between evaporation (increasing salinity) and precipitation (decreasing salinity).
©Copyright 1999 March 13, 1999 Send to Don Reed Department of Geology San Jose State University	#3 How many grams of dissolved salt are contained in 2000 grams of sea water with a salinity of 35^o/oo? a) 70 grams of dissolved salt b) 140 grams of dissolved salt c) 210 grams of dissolved salt d) None of the above.