1. Ocean characteristics, physical-chemical processes and man
1.2 PLANET OCEAN: introduction and terms
Type of system Marine Fresh water Terrestrial
Size 71% of earth surface 1-3% 26-28%
Dimensions Clearly 3D (average Much less 3D 2D
depth 4 km)
Conditions Uniform (still barriers) More diversity Very diverse
Surface Connection to other Depth Shores
water bodies
Oceans Large Broad-wide-deep Deep Continents
(av. depth 4 km) separated by
large distances
Seas Smaller Narrow-less-deep Less deep Closer to
(av. depth 500m) continents
1.2 MOVING OCEANS: about seafloor, winds and currents
1.2.1 Ocean floor – bathymetry
- Parts:
• Abyssal plain:
▪ ‘Flat’ interrupted by trenches and canyons
• Continental rise:
▪ Collection of all the mud fallen down (sediment deposits)
▪ Due to turbidity current: river entering the sea pushing the flow
▪ Slope <2%
• Continental slope:
▪ Cliff
▪ Slope 3-6%
▪ Depth down to 1500-2500m
• Continental shelf:
▪ Very shallow (7,5% of ocean surface)
▪ Slope 0.1%
▪ Average depth: 130m & width: 78km
- New seafloor created at mid-ocean ridge
• New material pushed up towards the continents
• Rather volcanic area
1
, - Activity:
• At the asthenosphere:
▪ Creates molten material → builds mountain ridges
• Subduction:
▪ 2 plates meet, and one goes under the other → under or normal mountains
• Divergent plates:
▪ 2 plates move away from each other → creates ridges, new material comes up
• Hydrothermal vents which release hot water from beneath the ocean floor
▪ Hot places with lots of nutrients specific type of ecosystems
1.2.2 Summary - provinces & zones
- 2 provinces:
• Neretic: area above the continental shelf (shallow area)
• Oceanic: area beyond continental shelf
- Pelagic: everything that lives in the water column
Zones:
• 0-100 m: epipelagic
• 200-1000 m: mesopelagic
• 1000-4000 m: bathypelagic
• 4000-6000 m: abyssopelagic
• 6000-10000 m: hadopelagic
- Benthic: everything that lives associated with the seafloor (zones same prefixes as zones of pelagic)
2
,1.2.3 Currents
- Current: movement of a mass of water from one place to another
• Transfer a lot of energy (so they determine our climates, T°)
• Surface currents are created by the wind
• Underwater currents are created by the chemical and physical characteristics
- Waves: change in the height of the water
• Water stays at one place
1.2.3.1. Wind patterns – create surface water currents
- Currents created by:
• Wind: creates surface currents
• Changes of physical and chemical characteristics of the seawater itself → underground
- Winds created by:
• High and low pressures due to atmospheric cells:
▪ Trades wind =
o Low pressure at the equator (0°)
o High pressure at 30° north
▪ Westerlies wind =
o Low pressure at 60° (north and south)
o High pressure at 30° (north and south)
• Not straight due to Coriolis force
- Coriolis force bend the wind
• To the right between 30° and 60°
• To the left between 0° and 30°, and between the poles and 60°
- Gyre: surface currents in a circle pattern
• 2 gyres in Atlantic, 2 in Pacific, 1 Indian
1.2.3.2. Deep sea currents
- Thermohaline circulation:
• Surface currents connected to deep sea currents like a conveyor belt
• Warm surface flow (surface sea current)
• Cool substance flow (deep sea current)
- Gulf stream to Europe (surface current) reaches Greenland and Iceland
Water cools down and becomes more dense
Becomes ice contains water and solutes (salt) = very dense
Moves down to the seafloor of the Atlantic → moves south
Reaches Antarctica and moves up against continent
= Antarctic divergence (AD)
3
, - Antarctic divergence (AD): place where water mass reaches the surface
Moves partly further south and partly back north:
▪ South moving becomes colder = denser
➔ Moves further down = Antarctic bottom water
➔ Moves back north to about 30° where it mingles with Atlantic deep water
▪ North moves up
➔ Hits surface water (=central water) around equator and goes under (denser)
➔ Becomes Antarctic intermediate water (=4th layer)
- Mediterranean water: pocket of water in the Atlantic which went through the Strait of Gibraltar
Too dense so goes down under water from Atlantic (=5th layer)
- Global impact of melting ice: downward force becomes weaker (less dense water)
Thermohaline circulation slows down → less transfer of heat → global change
1.3. SALTY OCEAN: about salinity and importance
1.3.1. Salinity what?
- Salinity: total amount of salts per kg of water (on average 35g/L water)
- Different types:
• Briny water: 50+ ppt
• Saline water (seawater, salt lakes): 30-50 ppt
• brackish water (estuaries, mangrove swamps, brackish lakes,…): 0.5-50ppt
• Fresh water (rivers, streams, aquifers, ponds, lakes): < 0.5 ppt
- Major constituents:
• Cl- (55.01), Na+ (30.40), SO4-2 (7.67), Mg2+ (3.91), Ca2+ (1.16), K+ (1.10)
- Constant ratio between major components so if you know amount chloride, you know the rest
• Salinity = 1.806 x chlorinity
- Nutrient concentrations are not constant, they vary with the biological activity
• [silica (SiO42-), nitrogen (NO3-, NO2-, NH4+), phosphorus (PO43-), iron (Fe(OH)3)]
1.3.2. Salinity affects organisms physiology
- Isotonic or iso-osmotic organisms: organisms where the body fluids are equal to the water salinity
• No osmosis e.g., squids
4
1.2 PLANET OCEAN: introduction and terms
Type of system Marine Fresh water Terrestrial
Size 71% of earth surface 1-3% 26-28%
Dimensions Clearly 3D (average Much less 3D 2D
depth 4 km)
Conditions Uniform (still barriers) More diversity Very diverse
Surface Connection to other Depth Shores
water bodies
Oceans Large Broad-wide-deep Deep Continents
(av. depth 4 km) separated by
large distances
Seas Smaller Narrow-less-deep Less deep Closer to
(av. depth 500m) continents
1.2 MOVING OCEANS: about seafloor, winds and currents
1.2.1 Ocean floor – bathymetry
- Parts:
• Abyssal plain:
▪ ‘Flat’ interrupted by trenches and canyons
• Continental rise:
▪ Collection of all the mud fallen down (sediment deposits)
▪ Due to turbidity current: river entering the sea pushing the flow
▪ Slope <2%
• Continental slope:
▪ Cliff
▪ Slope 3-6%
▪ Depth down to 1500-2500m
• Continental shelf:
▪ Very shallow (7,5% of ocean surface)
▪ Slope 0.1%
▪ Average depth: 130m & width: 78km
- New seafloor created at mid-ocean ridge
• New material pushed up towards the continents
• Rather volcanic area
1
, - Activity:
• At the asthenosphere:
▪ Creates molten material → builds mountain ridges
• Subduction:
▪ 2 plates meet, and one goes under the other → under or normal mountains
• Divergent plates:
▪ 2 plates move away from each other → creates ridges, new material comes up
• Hydrothermal vents which release hot water from beneath the ocean floor
▪ Hot places with lots of nutrients specific type of ecosystems
1.2.2 Summary - provinces & zones
- 2 provinces:
• Neretic: area above the continental shelf (shallow area)
• Oceanic: area beyond continental shelf
- Pelagic: everything that lives in the water column
Zones:
• 0-100 m: epipelagic
• 200-1000 m: mesopelagic
• 1000-4000 m: bathypelagic
• 4000-6000 m: abyssopelagic
• 6000-10000 m: hadopelagic
- Benthic: everything that lives associated with the seafloor (zones same prefixes as zones of pelagic)
2
,1.2.3 Currents
- Current: movement of a mass of water from one place to another
• Transfer a lot of energy (so they determine our climates, T°)
• Surface currents are created by the wind
• Underwater currents are created by the chemical and physical characteristics
- Waves: change in the height of the water
• Water stays at one place
1.2.3.1. Wind patterns – create surface water currents
- Currents created by:
• Wind: creates surface currents
• Changes of physical and chemical characteristics of the seawater itself → underground
- Winds created by:
• High and low pressures due to atmospheric cells:
▪ Trades wind =
o Low pressure at the equator (0°)
o High pressure at 30° north
▪ Westerlies wind =
o Low pressure at 60° (north and south)
o High pressure at 30° (north and south)
• Not straight due to Coriolis force
- Coriolis force bend the wind
• To the right between 30° and 60°
• To the left between 0° and 30°, and between the poles and 60°
- Gyre: surface currents in a circle pattern
• 2 gyres in Atlantic, 2 in Pacific, 1 Indian
1.2.3.2. Deep sea currents
- Thermohaline circulation:
• Surface currents connected to deep sea currents like a conveyor belt
• Warm surface flow (surface sea current)
• Cool substance flow (deep sea current)
- Gulf stream to Europe (surface current) reaches Greenland and Iceland
Water cools down and becomes more dense
Becomes ice contains water and solutes (salt) = very dense
Moves down to the seafloor of the Atlantic → moves south
Reaches Antarctica and moves up against continent
= Antarctic divergence (AD)
3
, - Antarctic divergence (AD): place where water mass reaches the surface
Moves partly further south and partly back north:
▪ South moving becomes colder = denser
➔ Moves further down = Antarctic bottom water
➔ Moves back north to about 30° where it mingles with Atlantic deep water
▪ North moves up
➔ Hits surface water (=central water) around equator and goes under (denser)
➔ Becomes Antarctic intermediate water (=4th layer)
- Mediterranean water: pocket of water in the Atlantic which went through the Strait of Gibraltar
Too dense so goes down under water from Atlantic (=5th layer)
- Global impact of melting ice: downward force becomes weaker (less dense water)
Thermohaline circulation slows down → less transfer of heat → global change
1.3. SALTY OCEAN: about salinity and importance
1.3.1. Salinity what?
- Salinity: total amount of salts per kg of water (on average 35g/L water)
- Different types:
• Briny water: 50+ ppt
• Saline water (seawater, salt lakes): 30-50 ppt
• brackish water (estuaries, mangrove swamps, brackish lakes,…): 0.5-50ppt
• Fresh water (rivers, streams, aquifers, ponds, lakes): < 0.5 ppt
- Major constituents:
• Cl- (55.01), Na+ (30.40), SO4-2 (7.67), Mg2+ (3.91), Ca2+ (1.16), K+ (1.10)
- Constant ratio between major components so if you know amount chloride, you know the rest
• Salinity = 1.806 x chlorinity
- Nutrient concentrations are not constant, they vary with the biological activity
• [silica (SiO42-), nitrogen (NO3-, NO2-, NH4+), phosphorus (PO43-), iron (Fe(OH)3)]
1.3.2. Salinity affects organisms physiology
- Isotonic or iso-osmotic organisms: organisms where the body fluids are equal to the water salinity
• No osmosis e.g., squids
4
