1. Chapter 6 Water
Oceans and Freshwater

2. Oceans 71 % of earths surface covered with water
97 % of the water is in oceans
In fact there is water around all the land

3. Three major oceans
Atlantic, Pacific, Indian

4. Ocean
Smaller, bodies of water almost surrounded by land are called seas.
Mediterranean Sea, Black Sea, and Arctic Ocean are considered part of the Atlantic Ocean

5. Black Sea
Mediterranean Sea

6. Oceans Pacific is larger than the Atlantic and Indian combined
Atlantic is second largest
Pacific is deepest ocean
Indian is second deepest
Oceans have salt water

7. Water Cycle
The circulation of water from oceans and lakes to the air and back.
Sun heats water
Water evaporates from ocean
Leaves dissolved salt behind
Water vapor is fresh water
Clouds move the water vapor

8. Water Cycle Precipitation is falling fresh water
Rain snow, sleet and hail
Some water flows back to ocean through rivers and streams
Some seeps into ground to become groundwater

11. Ocean Water A mixture of water and dissolved gases and solids
Water is H2O
96% of ocean water
4% dissolved stuff
Most elements have been found in ocean water

12. Ocean Water Sodium chloride most abundant Common table salt
Salinity – the number of grams of salt dissolved in 1 kilogram of water.
Units are parts per thousand (ppt)
If you evaporated 1 kilogram of water with a salinity of 35 ppt
You would have 35 grams of salts

13. Ocean Water Salinity of ocean water varies from place to place
Between 33 and 37 ppt

14. Ocean Water Sodium chloride 27.2 ppt Magnesium chloride 3.8 ppt
Magnesium sulfate 1.7 ppt
Calcium sulfate 1.3 ppt
Potassium sulfate 0.9 ppt
Calcium carbonate 0.1 ppt
Magnesium bromide 0.1 ppt

15. Sources Dissolved materials come from several sources
Volcanoes add gases, especially chlorine
Erosion adds dissolved salts
Rain erodes minerals
Rivers carry them into ocean
Source of potassium, sodium and magnesium

16. Sources
Waves dissolve the minerals in the rocks along the shore.

17. Salinity varies It is lower where rivers flow into oceans
Large rivers like the Mississippi and the Amazon have the biggest effect
Lots of freshwater dilutes the salt water.
In warm water lots of evaporation makes the water have higher salinity
In polar regions water freezes-
only fresh water
leaves the water with higher salinity

18. Dissolved Gases
Most abundant gases are nitrogen, oxygen, and carbon dioxide
Plants use carbon dioxide to make food
And release oxygen
Fish breathe the dissolved oxygen
Varies by depth
Alot at the surface
Mixes with the waves
Sunlight allows plants to exist

19. Dissolved Gases Varies with temperature of water
Warm water holds less gases than cold water
Cold water is more dense- sinks
In polar region oxygen rich water is carried to depths
Allows fish to live in deep water

20. Ocean Temperature Sun supplies the heat
Water temperature is highest at surface
Waves mixes surface water transfer heat downward
Region where heat is mixed is called the surface zone
In surface zone temperature is fairly constant
Surface zone varies in depth

21. Ocean Temperature Surface zone varies by location Caribbean thick
Off the coast of Maine thin
Varies with seasons
Thermocline- region below the surface zone
Water temperature drops with depth
Cold deep water doesn’t mix with warm surface water

22. Ocean Temperature
Deep zone- Extremely cold water from bottom of thermocline down
Three zones vary in thickness
In Arctic and Antarctic water is so cold there is no surface zone

23. The Ocean Floor
Topography- the description of the shape ocean floor and its features
Ocean floor is different from the continents.
It has higher mountains
Deeper canyons
Larger, flatter plains
Different type of rocks
More volcanoes

24. Continents Edge Called the continental margin Three parts
Continental shelf
Continental slope
Continental rise

25. Continental Shelf More like land than ocean floor
Slopes gently from the shoreline
Sediments from land are deposited
Varies in width
Atlantic 200 km
Siberia 1200 km

26. Continental Shelf Many minerals and deposits of gas and oil
Claimed by countries as part of their boundaries

27. Continental Slope Floor goes down rapidly- steep slope
Boundary between continent crust and ocean crust

28. Continental Rise Slopes more gently
Made of sediments that come off the shelf
Turbidity flows carry sediments down.
Like underwater avalanches of sediment and water

29. Submarine Canyons V shaped valleys cut through shelf and slope
Caused by turbidity flows
Bring deep water close to shore
Monterrey Bay
Good fishing

30. The Ocean Floor

31. The Ocean Floor Large flat areas are called abyssal plains
Biggest in Atlantic and Indian oceans
Because of sediments from large rivers like The Mississippi and Amazon and the Ganges and Indus Rivers
Trenches near the edge of continent trap Pacific sediments
Made up of mud silt and clay

32. Mountains Underwater mountains are called seamounts They are volcanoes
Some rise above to form islands
Like Hawaiian islands
Large flat-topped mountains underwater called guyots
Were worn away by waves.
Then the ocean level rose

33. Trenches Deep narrow crevices in the ocean floor
Near the edge of continents
Deepest is Marianas Trench m deep

34. Midocean Ridge Large underwater ocean ranges
Make one continuous chain around the world
Formed when molten liquid comes up and forms new crust
Consists of a valley between two parallel mountain ranges
Valley is called a rift valley

36. Reefs
Coral reefs are limestone made by organisms in shallow warm water
Warmer than 18°C
Shallower than 55 m
Three types of reefs
Fringing reefs around islands but touching
Barrier reefs separated from shore by a shallow lagoon
Atoll Reef surrounding a shallow lagoon no island

38. Coral Reefs
Charles Darwin was the first to explain how one changed into another.
Fringing reef forms in shallow water around volcanic island
Water level rises slowly so corals build up, bu valocano starts to sink, making a barrier reef
When volcano is completely gone- atoll

39. Ocean Life Zones Ocean life affected by Amount of sunlight Temperature
Pressure of water
Three major groups of life
Plankton- Float near the surface
Many types of alga
Source of food for many life forms.

40. Ocean Life Zones Neckton- ocean life that swims
Fish , whales , squid, octopus etc.
Can be predators
And avoid being prey
Benthos- live on the ocean floor
Plants where there is sunlight
Animals like crab, oyster, star fish

41. Ocean Life Zones Three major environments
Intertidal zone- the region below high and low tide
Most challenging for life
Sometimes underwater
Sometimes dry land
Waves breaking on them
Attach themselves to rocks to avoid being washed to sea

42. Ocean Life Zones
Neritic zone- From low tide to the edge of the continental shelf.
About 200 m deep
Low water pressure, fairly constant temperature
The most different plants and animals
Great fishing areas
Ends when sulight stops penetrating

43. Ocean Life Zones Two open ocean zones
Bathyal zone- Begins at continental slope and goes down 2000 m
Little or no sunlight
Many neckton
Abyssal zone
Little food for animals
Life forms are small and strange looking
Some produce their own light

44. Mapping the Ocean Floor
The deep ocean is difficult to measure
High pressure crushes ships
Earliest method is sounding
Dropping lines until they hit the bottom
Inaccurate and slow
Nets to bring ocean water and life up

45. Modern Techniques Instruments like underwater cameras
Underwater robots
Bathospheres and Bathyscaphs
Indirect methods like sonar
Send down sound waves
They hit bottom and bounce up
Detect signal
Use speed of sound to calculate distance

49. Freshwater Only 3% of all the water
Of that 85% is ice in glaciers and icecaps
That water is recycled in the water cycle
Water evaporates from ocean
Also evaporates from trees
And from lakes
Leaves the salt behind

50. Water cycle Next water condenses Changes back to liquid
Water must be cooled
As it rises
Forms clouds

51. Water cycle Next there is precipitation
There are so many water drops it falls out of clouds
Rain snow sleet and hail
When it hits the ground
Some evaporates
Some flows back to ocean
Some absorbed into ground to become groundwater- which flows back to ocean

52. Water Cycle

53. Frozen Water
Glaciers form when more snow falls in winter than melts in the summer.
Must be cold
Over the years snow piles up
Pressure turns it to ice
As ice gets thick, it starts to flow
Glaciers have 2% of the freshwater

54. Glaciers Those that form in mountains are called valley glaciers
Flow down the valleys
Rocks in the glacier wear away the valley walls
Make the valley U-shaped

55. Glaciers In polar regions ice builds up in thick sheets
Form continental glaciers
Cover millions of square kilometers
Move slowly in all directions
Found in Greenland and Antarctica
One time covered much of America
Icebergs break off glaciers

57. Standing water Water caught in low places as it runs off
Ponds and lakes
Depressions caused by former glaciers are common places for lakes
Or where there are blockages
Ponds tend to be smaller and shallower than lakes

58. Standing water Reservoirs are artificial lakes
Made by damming rivers and streams
Water backs up
Used for drinking water, irrigation, recreation, and electric power

59. Running water
Precipitation that doesn’t soak in flows into rivers and streams is called surface runoff
Some soils soak up more than others
Have more pore space
Empty space between particles
Less runoff
Plants roots absorb water

60. Running water More runoff when there has been recent rains
Watershed is the land area that drains into a river or stream
Some are huge- like the Mississippi
Are divided by mountain ranges and ridges

61. Watershed

63. Groundwater Water below the surface
More fresh water underground than on the surface
Precipitation move down through spaces between the rocks and soil
Spaces are called pores
Permeable rock lets water through
Sandstone- large pores

64. Groundwater Impermeable rock does not let water through
Clay small pores
Water moves downward until it reaches an impermeable layer
Water fills up the permeable layers above
Where water fills is called the zone of saturation
Where pores are filled mostly with air is called the zone of aeration

65. Water Table Boundary between the zones
Water table is shallow near the ocean
In the mountains it can be deep
Where it rains a lot, it is shallow
Where it is dry, it is deep
Shallower in wet season
Deeper in dry season
Can be lowered by overuse

66. Aquifer
A layer of underground water flowing horizontally through permeable rock
Trapped above impermeable rock
Reached by digging wells
Pollution travels through them easily

67. Artesian Well
If aquifer trapped between two layers of impermeable rock,
Pressure builds up and forms an artesian well
Water flows out of the ground by itself without pumping

68. Artesian Well

69. Caverns
Water can slowly dissolve underground rock to form open tunnels
Especially common in limestone
Acidic water eats through it easily.