Characteristics of Ocean Water

• Oceanography covers physical properties of the ocean:

–Dissolved materials: minerals and salts (salinity) and gases

–Properties that change with depth: light, temperature and pressure

–Motion: Waves, tides, currents

Waters Unique Properties…

-Found in 3 states of matter on our planet

-High heat capacity: ability of water to hold heat energy and regulate our climate

-Universal solvent: can dissolve more things than any other solvent

Unique Properties of water are due to

Hydrogen Bonding-attraction between water molecules because of the unequal charges of O & H

• Charges on O and H help it dissolve things like salts

• Attraction between water molecules- a lot of heat is needed to increase water temp and when water cools it release a lot of heat

Salinity

• Result of weathering of rocks on land carried by rivers to the ocean

• Materials from the earth’s interior– Hydrothermal vents– Volcanic eruptions

Materials in Seawater

–Oceans have an average salinity of 3.5% or 35 ppt (35 ‰)

– ppt= parts per thousand

–More than 70 elements in seawater but the main ones are..

ChlorideSodiumSulphateMagnesiumCalciumPotassium

Dissolved Gases

• Oxygen, carbon dioxide and nitrogen

• Dissolve into the ocean from the atmosphere through wave action

• Dissolve better in cold water

• Animal life can change the chemistry of ocean gases

• Around 500 m water runs out of oxygen

–Bacteria and other animals are using it during decomposition and respiration

• Animals in this region and lower have large gills, modified hemoglobinor are inactive

Pressure

• We are under 1 atmosphere (atm) of pressure on land

• Water is heavier than air so every 10 m deep = 1 more atm of pressure

Animal Adaptations and Pressure

• Ocean life has adapted to deep ocean and 1000x our pressure with lightweight skeletons, little musculature, and reduced metabolic, growth and reproductive rates.

• Diving mammals have rib cages that collapse and expand in result to changing pressure

Water Depth vs Light• Photosynthetic organisms use light to

make sugars.

• Sunlit area (top 100 meters) contains 90% of marine life

• Colors of penetrate thru water differently

– Red light filters out first and blue light goes the furthest

– Red animals are essentially invisible in deep waters

Energy in the Ocean

• Ocean takes longer to heat and cool than land due to its specific heat

• Water temp decreases with depth

Animal Adaptations and Temperature• Colder temps reduce the metabolic rate• In very cold waters fish have a special

protein like antifreeze to keep tissues from freezing

• Lighter colored animals stay cooler than darker colored animals and are found in warmer waters

• Some marine life have thick layers of fat to insulate their bodies

Motion in the Ocean…Tides• Daily rise and fall of the ocean (high

and low tide)• Range as small as 1 m & as high as

20m• Some areas have 1 or 2 high & low

tides• Caused by gravitational pull of moon

on our ocean basin

TIDES•Tides rise (FLOOD) to produce a HIGH TIDE

• And fall (EBB) (LOW TIDE)

Moon/

Sun

This side is pulled towards the Sun and/or Moon by gravitational attraction

This side bulges out because of inertia

Therefore, there are two high tides on Earth at any one time

Marine Life and Tides• Some marine life time their

reproduction to the high or low tide cycle

• Horseshoe crabs come ashore to mate on the night of a high tide in May

• Eggs hatch 2 wks later on a high tide and are washed into the ocean

Motion in the Ocean…Waves

• Winds produce waves as it blows across the ocean’s surface

• When waves enter shallow water they drag along the ocean floor

• The wave top is moving faster than the wave bottom so it topples forward

• Specialty waves: rogue waves, tidal waves and tsunamis

At the shoreline

• Surf - sequence of breaking waves

• Swash - water sliding up beach

• Backwash - water flowing back down beach to sea

Longshore drift• Waves arrive at a

coast at an angle (swash)

• Backwash returns at 90 degrees

Sand is moved along the beach = longshore drift or longshore current

Coastal deposition

• Result of longshore drift and a lot of sediment

• produces extensions of deposit from the shoreline

• May grow across a bay (baymouth bar)

• May link an island to the main land (tombolo)

spit = curved extension

Motion in the Ocean-Currents

• Rivers of water moving through the ocean

• Surface currents caused by major wind belts

• Deflected by the Coriolis Effect• Important in moving marine life

and nutrients around the oceans

Vertical Ocean Currents

• Differences in temperature and salinity change the density of water.

• This causes sinking and rising of water in the ocean

• Ocean conveyor belt- convection current of water moving between the equator and poles in the oceans

• Takes 1600 years to cycle