Transcript Salt Water - Allen ISD

Chapter 12
The Gulf of Mexico
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 floats
B. 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. Pycnocline- 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
IV. Composition of Saltwater
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)
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 Salinity
A. 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 Thousand
1. 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
VI. Salinity Variations
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.
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.