1. Chemical And Physical Features of Seawater Chapter 3

2. 2 Water- a unique compound Water is a polar molecule (slightly charged) Water is a polar molecule (slightly charged) Water molecules are attracted to one another – hydrogen bonds. Water molecules are attracted to one another – hydrogen bonds. Water exists in all three states of matter here on Earth! Water exists in all three states of matter here on Earth!

3. 3 Hydrogen Bonds between water molecules

4. 4 Three States of Water Liquid- weak hydrogen bonds are constantly being formed and broken Liquid- weak hydrogen bonds are constantly being formed and broken -molecules slide past one another. -molecules slide past one another. When a molecule moves fast enough to break free, it enters the gaseous form When a molecule moves fast enough to break free, it enters the gaseous form -This is evaporation. -This is evaporation.

5. 5 Water in its liquid state

6. 6 Three states of water (cont’d) If enough energy is added, the hydrogen bonds are all broken quickly, this is when water boils. If enough energy is added, the hydrogen bonds are all broken quickly, this is when water boils. Density-like air, water becomes denser as it cools. Density-like air, water becomes denser as it cools. Ice- the crystal structure of ice is actually less dense than the liquid, causing ice to float Ice- the crystal structure of ice is actually less dense than the liquid, causing ice to float

7. 7 Three States of water

8. 8 Heat capacity- Heat capacity- a substances ability to store energy- water has a very high heat capacity!!!! Heat capacity- a substances ability to store energy- water has a very high heat capacity!!!! Takes a lot of energy to heat water! Takes a lot of energy to heat water! Takes a long time to cool! Takes a long time to cool!

9. 9 Water- the universal solvent Water can dissolves more substances than any other natural compound Water can dissolves more substances than any other natural compound -esp. salts! -esp. salts! This is because it is polar- it can dissolve many ionic compounds. This is because it is polar- it can dissolve many ionic compounds.

10. 10 Water molecules dissolving NaCl

11. 11 Characteristics of Seawater- the solutes Chemical Weathering- Rocks on land are dissolved by rainwater and groundwater- carried to the ocean by rivers Chemical Weathering- Rocks on land are dissolved by rainwater and groundwater- carried to the ocean by rivers Hydrothermal vents- release minerals into the sea Hydrothermal vents- release minerals into the sea Volcanoes- release substances that enter the ocean by rain and snow Volcanoes- release substances that enter the ocean by rain and snow

12. 12

13. 13 Salinity Only a few ions make up the majority of solutes in the ocean Only a few ions make up the majority of solutes in the ocean Na+ and Cl-, make up ~85%!!!! Na+ and Cl-, make up ~85%!!!! Salinity- the total amount of salt dissolved in seawater Salinity- the total amount of salt dissolved in seawater expressed in PSU (practical salinity units) or ‰ (parts per thousand) expressed in PSU (practical salinity units) or ‰ (parts per thousand)

14. 14 Salinity of seawater- 35‰

15. 15 Salinity (cont’d) Rule of constant proportions- the proportions of salts in the ocean remains constant. Rule of constant proportions- the proportions of salts in the ocean remains constant. Discovered by the H.M.S. Challenger! Discovered by the H.M.S. Challenger! * there are slight variations in some areas * there are slight variations in some areas ex- near rivers, vents ex- near rivers, vents

16. 16 Density of Seawater- Determined by two major factors Determined by two major factors 1. Temperature- temp increases, density decreases 1. Temperature- temp increases, density decreases 2. Salinity- salinity increases, density increases 2. Salinity- salinity increases, density increases Can be measured at different depths using a Niskin bottle Can be measured at different depths using a Niskin bottle

17. 17 Niskin bottles- used for water sampling

18. 18 Figure 3.09

19. 19 Sea Surface Temperatures of the World Ocean

20. 20 Dissolved gases Three most important: Three most important: 1. Oxygen 1. Oxygen 2. Carbon Dioxide (80%) 2. Carbon Dioxide (80%) 3. Nitrogen 3. Nitrogen Gases dissolve more easily in colder water! Gases dissolve more easily in colder water! Gas exchange between the ocean and the atmosphere occurs at the surface Gas exchange between the ocean and the atmosphere occurs at the surface

21. 21 Transparency Different colors of light penetrate the ocean at varying depths Different colors of light penetrate the ocean at varying depths Red is absorbed quickly Red is absorbed quickly Blue can travel to the greatest depths Blue can travel to the greatest depths

22. 22

23. 23 Figure 3.12 Secchi disc for measuring water clarity

24. 24 Pressure On land, we experience 1 atm, or 14.7 psi On land, we experience 1 atm, or 14.7 psi In the ocean, organisms experience this PLUS the weight of the water. In the ocean, organisms experience this PLUS the weight of the water. Pressure increases 1 atm with every 10 meters in depth. (an extra 14.7psi with every 33 ft) Pressure increases 1 atm with every 10 meters in depth. (an extra 14.7psi with every 33 ft) Gases expand and contract with pressure changes Gases expand and contract with pressure changes

25. 25

26. 26 Figure 3.14

27. 27 Three layered structure of the ocean Cold, salty water sinks- the ocean is stratified. Cold, salty water sinks- the ocean is stratified. Warmer water stays near the surface Warmer water stays near the surface The layer of rapid temperature change in between is called a thermocline. The layer of rapid temperature change in between is called a thermocline.

28. 28 The three layers 1. Warm, surface water 1. Warm, surface water 2. Intermediate layer, or main thermocline 2. Intermediate layer, or main thermocline 3. Deep or bottom layers (very cold, salty, DENSE!!!) 3. Deep or bottom layers (very cold, salty, DENSE!!!)

29. 29 Temperature Profile of a water column

30. 30 Comparison of thermoclines in different climates

31. 31

32. 32 Thermohaline circulation Deep water circulation that is driven by density of a water mass Deep water circulation that is driven by density of a water mass Generated when there are very cold surface temperatures Generated when there are very cold surface temperatures Cold water mass sinks, generating the current Cold water mass sinks, generating the current

33. 33 The Great Ocean Conveyor Belt

34. 34

35. 35 Figure 3.17

36. 36 Surface movements of the ocean Surface currents are generated by wind Surface currents are generated by wind Wind is generated by sun’s energy Wind is generated by sun’s energy Winds do not travel in a straight line Winds do not travel in a straight line Deflected by the Coriolis Effect, which is caused by Earth’s rotation. Deflected by the Coriolis Effect, which is caused by Earth’s rotation. These complex winds generate surface currents and waves in the ocean These complex winds generate surface currents and waves in the ocean

37. 37 Heating of the Earth’s surface generates winds

38. 38

39. 39 Global surface patterns- the circular patterns are called gyres

40. 40 Surface currents and sea surface temperatures

41. 41 Waves- also generated by winds Anatomy of a wave- Anatomy of a wave- Wavelength- distance from crest to crest Wavelength- distance from crest to crest Height- distance from crest to trough Height- distance from crest to trough Period- time for a wave to go by a given point Period- time for a wave to go by a given point

42. 42 Parts of a wave

43. 43 Energy of the wave moves forward, the actual water moves in a circle

44. 44 Size of the wave grows with distance

45. 45 Life cycle of a wave

46. 46 Tides Caused by the gravitational attraction of the moon AND the sun on Earth’s ocean, combined with earth’s rotation Caused by the gravitational attraction of the moon AND the sun on Earth’s ocean, combined with earth’s rotation Centrifugal force- causes second high tide Centrifugal force- causes second high tide Most places experience 2 high and 2 low tides each 24 hours and 50 min. Most places experience 2 high and 2 low tides each 24 hours and 50 min.

47. 47 Figure 3.29

48. 48 Figure 3.30

49. 49 Spring and Neap tides Tidal range- difference in water level between low and high tides Tidal range- difference in water level between low and high tides Spring tides- occur during new and full moons when sun, moon and earth are in a line Spring tides- occur during new and full moons when sun, moon and earth are in a line Large tidal range Large tidal range Neap tides- occur during first and third quarter. Neap tides- occur during first and third quarter. Smaller tidal range- tides not as ‘extreme’ Smaller tidal range- tides not as ‘extreme’

50. 50 Figure 3.31

51. Types of tidal patterns

52. 52 Semidiurnal tides- 2 high and 2 low tides each 24 hours and 50min.

53. 53 Mixed semidiurnal- similar to semidiurnal, but one of the high tides is larger

54. 54 Diurnal- one high and one low tide- highly unusual

55. 55 Figure 3.33

56. 56

57. 57 Pg. 59