Properties of the Ocean

I. Density The Density of water is affected by two things:A. Temperature

1. As water temperature decreases, density increases and volume increases. Once water becomes ice the density then decreases.

Result: ice forms and floatsB. Salinity 1. When salts dissolve in pure water, the water’s density increases Result: freshwater floats on saltwater.

II. Stratification A. Occurs when water masses with

different properties form layers according to density. B. Types of stratifications 1.Thermocline-layering of water by temperature 2. Halocline-layering of water by salinity. 3. Pynocline- layer formed by a rapid change in water’s density due to changing temperature and salinity.

III. Where Does The Salt Come From?A. Degassing – the releasing of volatile chemicals after

the Earth's formation and during volcanic activity (rained)B. Erosion - of sediments and basalts on land by weathering (Basalts-dark, heavy volcanic rocks that makes up most of the world's oceanic crust)C. Oceanic Crust – reactions in basalt releases chemicals into the seawater.

This specimen was erupted from Kilauea volcano in 1960.

Where Does The Salt Come From?

D. Biological Processes - produce organic chemicals and cycle bio-reactive elements

E. Photochemical Reactions - occur in the upper

pelagic waters (water not close to the bottom or near the shore)

F. Radioactive Decay - elements forming other

elements

A. Seawater contains almost every known natural

element. 72 have been identified.B. Most abundant materials are chloride and

sodium (seawater tastes like table salt – Sodium Chloride)

IV. Composition of Saltwater

Component Concentration Percentage of Salinity

chloride 18.98 55.03

sodium 10.56 30.59

sulfate 2.65 7.68

magnesium 1.27 3.68

calcium 0.4 1.18

potassium 0.38 1.11

bicarbonate 0.14 0

C. Salt water is 96.5% H2O molecules

V. Measuring SalinityA. Specific Gravity

1. The specific gravity is a comparison of a substance’s density to that of water. 2. Written as a decimal. 3. The specific gravity of ocean water - 1.025 S.G.

B. Parts Per Thousand1. Measure of the amount of dissolved

substance per thousand units of the other.

2. symbol used is o/00. 3. The salinity ocean water is 35 0/00

A. The variations in salinity are affected by the melting of

ice, inflow of river water, evaporation, rain, snowfall,

wind, wave motion, and ocean currents ( causing horizontal and vertical

mixing of the saltwater.)

B. The saltiest water (40 0/00) occurs in the Red Sea and the Persian Gulf, due to very high rates of evaporation.

VI. Salinity Variations

C. The North Atlantic is the saltiest ocean; averaging about 37.9 o/oo. The saltiest part is the Sargasso Sea; created by floating brown seaweed called "sargassum". High temperatures equals a high rate of evaporation and the area receives no fresh-water inflow due to its location.

D. Low salinities occur in polar seas diluted by

melting ice and rain. The Baltic Sea’s salinity is

between 5 to 15 o/oo and the Black Sea is less than

20 o/oo. Puget Sound in the Tacoma, Wash.ranges

from 21-27 o/o0 due to fresh-water streams.