1. Chapter 4 Section 2

2. Salt Water Composition of seawater
most salts present in seawater are present in their ionic form
6 ions make up 99% of dissolved salts in the ocean:
sodium (Na+)
magnesium (Mg2+)
calcium (Ca2+)
potassium (K+)
chloride (Cl-)
sulfate (SO42-)
trace elements - present in concentrations of less than 1 part per million

3. Table 4-2 Major Ions In Seawater.

4. Salt Water Salinity seawater = 3.5% salt, 96.5% water
expressed as in g per kg water or parts per thousand (ppt)
salinity of surface water varies as a result of evaporation, precipitation, freezing, thawing, and freshwater runoff from land
between 10o N-10o S of equator = low salinity (due to heavy rainfall)
areas around 30o N and 30o S = high salinity (evaporation > precipitation)
from 50o = low salinity (heavy rainfall)
poles = high salinity (freezing – removes water from sea)

5. Figure 4-5 Ocean Salinity.

6. Salt Water Cycling of sea salts sea salt originally from earth’s crust
ocean composition has remained the same due to balance between addition through runoff & removal
salts removed in many ways:
form insoluble complexes that precipitate to ocean floor
depositing on land by sea spray
evaporites (salt deposits)
concentration in tissues of organisms harvested for food
Adsorption - process of ions sticking to surface of fine particles, which sink and are trapped in sediments

7. Figure 4-6 Sea Salt Cycling.

8. Hydrogen sulfide (H2S) Chlorine (Cl2) Sulfur Chloride (Cl–)
Precipitation
Chloride (Cl–)
Sulfate (SO42–)
Hydrogen sulfide (H2S)
Chlorine (Cl2)
Volcano
Sulfur
Sea spray
removes salts
Salts removed
when organisms are
caught for food
River
discharge
Carbonate (CO32–)
Calcium (Ca2+)
Sulfate (SO42–)
Sodium (Na+)
Magnesium (Mg2+)
Calcium (Ca2+)
Magnesium (Mg2+)
Potassium (K+)
Rock on
the seafloor
Clay particles
adsorb
Organisms
die
Bottom sediments
Precipitation
Stepped Art
Fig. 4-6, p. 75

9. Salt Water Gases in seawater gases from biological processes
oxygen is a by-product of photosynthesis
release of CO2 from respiration
oxygen-minimum zone – located just below sunlit surface waters
solubility of gases in seawater
seawater has more O and CO2 but less N than the atmosphere
relative solubility in seawater: CO2 > O > N
affected by temperature, salinity and pressure

10. Table 4-3 Gases Found in Seawater

11. Figure 4-7 (a) Gases In Seawater.

12. Salt Water role of bicarbonate as a buffer
bicarbonate formed from the solution of CO2
buffer - a substance that can maintain the pH of a solution at a relatively constant point
bicarbonate’s buffering action helps maintain the pH of seawater at a constant value, providing a stable environment for marine organisms

13. Figure 4-7 (b) Gases In Seawater.

14. Ocean Heating and Cooling
Earth’s energy budget
energy input
sun’s radiant energy heats earth’s surface
spherical shape + presence of the atmosphere cause the amount of radiant energy reaching earth’s surface to decrease with increasing latitude

15. Figure 4-8 Distribution of Solar Energy.

16. Greater angle Less solar energy per unit area Tropic of Cancer
Right angle
More solar energy
per unit area
Equator
Tropic of Capricorn
Greater angle
Less solar energy
per unit area
Stepped Art
Fig. 4-8, p. 77

17. Ocean Heating and Cooling
Earth’s energy budget
energy output
excess energy absorbed by the earth is transferred to the atmosphere by evaporation and radiation
accumulation of greenhouse gases (CO2, methane, chlorofluorocarbons (CFC’s)) can prevent heat energy from radiating back to space

18. Figure 4-9 The Earth’s Energy Budget.

19. by clouds Absorbed by atmosphere and clouds Radiation from atmosphere
Reflected
by ground by
clouds
Absorbed by
atmosphere
and clouds
Radiation
from
atmosphere
Absorbed
by rock,
soil, and
water on
the
surface
Convection
and
conduction
to the
atmosphere
Scattered and
deflected by
atmosphere
Heat
transferred
via
evaporation
Radiation
from earth
Radiation to
atmosphere
and clouds
Stepped Art
Fig. 4-9, p. 78

20. Ocean Heating and Cooling
Sea temperature
temperature varies daily and seasonally
affected by energy absorption at the surface, loss by evaporation, transfer by currents, warming/cooling of atmosphere, heat loss through radiation
seasonal variations in the amount of solar radiation reaching the earth, occur especially between 40o and 60o N and S because angle of sun’s rays change dramatically at these latitudes seasonally

21. Figure 4-10 Average Surface Temperatures Of The World Ocean.