OCEANS

1. OCEANS Pages 661-668

2. Ocean Water is not pure! • Two main dissolved gases = N2 and O2. • CO2 (in large amounts) • Other atmospheric gases (in small amounts)

3. Gases enter the ocean from… • the atmosphere (most O2 enters this way) • underwater volcanoes • marine organisms • streams and rivers

4. Temperature and Dissolved Gases • Gases dissolve more readily in COLD water. • Water at the surface of the ocean in COLD regions dissolve larger amounts of gases than water in WARM tropical regions. • Gases can return to atmosphere from ocean (evaporation).

5. Carbon Sink • Ocean = 60X as much Carbon as atmosphere • CO2 trapped in ocean for years and years • Ocean is a carbon sink….b/c ability to dissolve and contain a lot of CO2 • CO2 traps thermal energy, so ocean is important in climate regulation

6. Dissolved Solids • Ocean water = 96.5% pure water and 3.5% dissolved solids called sea salts • Dissolved solids made of 75 elements. • Ocean water mostly…Cl, Na, Mg, S, Ca, K • 85% of solids is HALITE • Trace elements(in small amounts) Au, Zn, P

7. Sources of Dissolved Solids • Volcanic eruptions • Chemical weathering of rock on land • Chemical reactions b/t sea water and newly formed sea floor rocks

8. Salinity of Ocean H2O • Salinity – measure of the amount of dissolved salts and other solids in a given liquid • Measured by # grams of dissolved solids in 1,000 grams ocean water (parts per thousand or ‰) • Higher salinity = better conductivity

9. Factors that Change Salinity • Precipitation = fresh water • Ocean water evaporates or freezes…only H2O molecules removed • Rate of evaporation higher than precipitation = salinity of surface water increases • Equatorial water = salinity lower • Salinity ranges 33‰ to 36 ‰, average 34.7 ‰

10. Temperature of Ocean Water • Varies with depth and location on the surface • Temperature range is affected by amount of solar energy and movement of water in the ocean

11. Surface Water • Heat is distributed downwards to 100-300 m (this zone is relatively constant and decreases slightly as depth increases). • Temperature of surface water decreases as latitude increases • Ocean water freezes at -1.9°C. • Pack ice – floating layer of sea ice completely covers an area of an ocean surface; ≤5 m thick; insulates water below it

12. Thermocline • Thermocline – layer in a body of water in which water temperature drops with increased depth faster than it does in other layers • Changing temperatures or shifting currents alter the depth of the thermocline or cause it to disappear

13. Deep Water • Density of cold, deep water controls slow movement of deep ocean currents • Cold, deep ocean water holds more dissolved gases than warm, shallow ocean water

14. Density of Ocean Water • Density = mass/volume • Density of pure water = 1 g/cm3 • Salinity and temperature affect density! • Density of ocean water = 1.020 – 1.029 g/cm3 • Ocean water becomes denser as it gets colder and saltier • Densest ocean water = polar regions

15. Ocean Water Color • Determined by the way it absorbs or reflects sunlight • White light from sun has all visible wavelengths of EMS • All colors are absorbed by the water except, blue, it is reflected allowing the color blue to be seen

16. Why Ocean Color is Important • Phytoplankton – microscopic plants in the ocean that provide food to many of the ocean’s organisms; absorb red and blue light; reflect green light • Presence of phytoplankton affect shade of blue of the ocean • Phytoplankton require nutrients; presence or absence of them indicate health of ocean