Chemical and Physical Properties of Seawater Chapter 3, p 44 - 68.

Chemical and Chemical and Physical Physical

Properties of Properties of SeawaterSeawater

Chapter 3, p 44 - 68Chapter 3, p 44 - 68

SpecificsSpecificsProperties of waterProperties of water

Ocean CirculationOcean Circulation

Waves and TidesWaves and Tides

Brainstorm with a partner!Brainstorm with a partner!

Unique properties Unique properties

of waterof waterAll 3 states of matter on EarthAll 3 states of matter on Earth

Very polar moleculeVery polar molecule

Hydrogen bondingHydrogen bonding

EvaporationEvaporation

Liquid Liquid Gas Gas

Hydrogen bonds brokenHydrogen bonds broken

Density and temperatureDensity and temperature

Unique Nature of Water

With lower temperatures, water molecules move closer to one another.

Imagine a gallon bucket of seawater.

At 75 degrees, the molecules are further apart than when this same gallon of water is at 35 degrees.

When molecules are closer together, the substance is said to have more density.

Higher density = heavier, even when volume is the same.

Unique properties Unique properties of Waterof Water

So… cold water sinks below warmer waterSo… cold water sinks below warmer water

Colder water also holds more oxygen than the Colder water also holds more oxygen than the same volume of water.same volume of water.

Great for all those organisms living at the Great for all those organisms living at the ocean floor.ocean floor.

Now, even though colder water is more dense Now, even though colder water is more dense than warmer water, this changes when the than warmer water, this changes when the water gets cold enough to freeze.water gets cold enough to freeze.

Ice floats and acts as barrier to cold air for Ice floats and acts as barrier to cold air for marine organisms living in the water.marine organisms living in the water.

Temperate and Temperate and StateState

Less dense as a solid than a liquid. Less dense as a solid than a liquid. Habitat and insulation for organismsHabitat and insulation for organisms

HH++ bonds result in higher melting and bonds result in higher melting and freezing temp.freezing temp.

High Heat High Heat CapacityCapacity

Water is able to absorb a lot of heat Water is able to absorb a lot of heat with a relatively small increase in with a relatively small increase in temperaturetemperature

HIGH heat capacity – amount of heat HIGH heat capacity – amount of heat needed to raise a substance’s needed to raise a substance’s temperature by a given amounttemperature by a given amount

Important for marine organismsImportant for marine organismsNot exposed to rapid changes in Not exposed to rapid changes in temperaturestemperatures

Latent heat of Latent heat of meltingmelting

Latent heat of melting – the amount of Latent heat of melting – the amount of heat required to melt a substanceheat required to melt a substance

Absorbs A LOT of heat when it melts – Absorbs A LOT of heat when it melts –

Hydrogen bonds break, but motion of Hydrogen bonds break, but motion of molecules does not speed up until all of molecules does not speed up until all of the ice melts.the ice melts.

It takes A LOT of energy to break It takes A LOT of energy to break hydrogen bonds!hydrogen bonds!

Without HWithout H++ bonds, ice would melt at about bonds, ice would melt at about -90°C instead of 0°C-90°C instead of 0°C

Water CycleWater Cycle

Properties of Properties of SeawaterSeawater

Water is the universal solventWater is the universal solvent

Ion dissociation

SeawaterSeawaterSalinity – total Salinity – total amount of salt amount of salt dissolved in dissolved in seawaterseawater

Not just NaNot just Na++ and Cl and Cl--

Lots of salts!Lots of salts!

See p. 48, Table 3.1See p. 48, Table 3.1

Where do the salts Where do the salts come from?come from?

Where might ion concentrations of seawater differ from the normal amounts?

Salinity, Salinity, Temperature, Temperature,

Density Density More salty = More denseMore salty = More dense

Lower temperature Lower temperature more dense more dense

Measuring temperature and salinity at Measuring temperature and salinity at specific points in the ocean – Niskin specific points in the ocean – Niskin bottlesbottles

Le t ’s take a look!

Temperature Temperature ProfileProfile

Temperature, Temperature, salinity, other salinity, other physical physical characteristics characteristics and even and even plankton can be plankton can be sampled at sampled at several depths at several depths at onceonce

SSTSSTSatellite ImagesSatellite Images

Current Conditions

Temperature and Temperature and SalinitySalinity

SST of NE coast of the United States. Do you know the current?

Dissolved GasesDissolved GasesOxygen (OOxygen (O22) – not very soluble) – not very soluble

Most released through photosynthesisMost released through photosynthesisAmounts also dependent upon respirationAmounts also dependent upon respiration

Carbon Dioxide (COCarbon Dioxide (CO22) – more soluble) – more soluble80% of dissolved CO80% of dissolved CO22 is in ocean is in ocean

Nitrogen (NNitrogen (N22))

Exchange occurs at surface of waterExchange occurs at surface of waterAtmosphere to oceanAtmosphere to ocean

Gas dissolves best in cold waterGas dissolves best in cold water

Oxygen Content of Oxygen Content of OceanOcean

High oxygen content High oxygen content near the sea surfacenear the sea surface

Low oxygen at mid-Low oxygen at mid-depthdepth

Increase in oxygen Increase in oxygen in the water ~ 1 km in the water ~ 1 km water below sea water below sea levellevel

COCO22 in the Ocean in the Ocean

FACT: 80% of the world’s COFACT: 80% of the world’s CO22 is found in the ocean. is found in the ocean.

How is this affecting our oceans?How is this affecting our oceans?

COCO22 Emissions Emissions

CO2 is much more soluble than oxygen

CO2 makes up more than 80% of the dissolved gas in the ocean, compared to less than 0.04% of air

Ocean stores more than 50x as much total CO2 as the atmosphere.

Amounts of CO2 in the oceans are increasing.

Light ConditionsLight ConditionsCOCO22 + H + H22O + sun energy O + sun energy C C66HH1212OO66 + O + O22

CC66HH1212OO66 + O + O22 CO CO22 + H + H22O + energy O + energy

Must have the right light conditions to Must have the right light conditions to fuel photosynthesis!fuel photosynthesis!

Light levels change with depth.Light levels change with depth.

Visible Light Visible Light SpectrumSpectrum

Photos courtesy of www. science.nasa.gov

Colors of the Colors of the OceanOcean

Depth of 30 m: Only blue light remains:(a)Under natural lighting this sea star appears light blue, with the tips of the arms almost black. (b)A flash reveals the sea star’s true colors.

1. Photic zone – sunlit, 200 meters below the surface of the ocean2. Twilight zone - from about 200 - 2000 meters below the surface. 3. Abyssal zone – no sunlight, from 2000 - 5000 meters below the surface to the bottom of the ocean.

Light ZonesLight Zones

Light Penetration Light Penetration of Surface Watersof Surface Waters

Gathering DataGathering Data

Pressure in the Pressure in the OceanOceanOrganisms on land are under 1 atm (14.7 Organisms on land are under 1 atm (14.7

lbs/sq in or psi) at sea level. The weight of all lbs/sq in or psi) at sea level. The weight of all the air above them.the air above them.

Marine organisms are under the weight of Marine organisms are under the weight of water AND the atmosphere. water AND the atmosphere.

Since water is much heavier than air, marine Since water is much heavier than air, marine organisms are under much more pressure organisms are under much more pressure than those on land. than those on land.

As the pressure increases, gases are As the pressure increases, gases are compressed. Gas-filled structures inside compressed. Gas-filled structures inside organisms like air bladders, floats, and lungs organisms like air bladders, floats, and lungs shrink or collapse.shrink or collapse.

Limits depth range of organismsLimits depth range of organismsWe need special equipment to go deep or We need special equipment to go deep or special instruments that can withstand special instruments that can withstand pressurepressure

Pressure in the Pressure in the OceanOcean

Ocean CirculationOcean CirculationCurrents move ocean waters around the Currents move ocean waters around the world’s oceans at different depths (Ocean world’s oceans at different depths (Ocean Conveyer Belt)Conveyer Belt)

Waves, currents, tides, and gyresWaves, currents, tides, and gyres

Wind patternsWind patternsUltimately driven by sunlight energyUltimately driven by sunlight energy

Currents circulate heat, nutrients, Currents circulate heat, nutrients, pollution, and organismspollution, and organisms

Drives Earth’s climateDrives Earth’s climateNew Gulf Current

WindsWindsAs sunlight heats air, air rises.

Cooler air rushes in to take the place of air that has risen.

This movement is the source of winds.

Ever notice how the winds at the coast are stronger during the day than at night?

Winds created in this manner continuously at the equator are known as the Trade Winds.

The Westerly's in the mid latitude and the Easterlies at the poles are less consistent than the Trade Winds.

Air near equator is warmed by solar heating and rises. Air from higher latitudes moves in over the Earth’s surface to replace the rising air, creating winds. The TRADE WINDS are deflected by the Corliolis effect and approach the Equator at an angle of about 45°.

Trade WindsTrade Winds

30°S

30°N

Doldrums

The major wind patterns are created by the rising of sun-warmed air and the sinking of cold air.

How do the continents effect the wind patterns?

Global Wind Global Wind PatternsPatterns

Major Surface Major Surface CurrentsCurrents

The Coriolis EffectThe Coriolis Effect

If the Earth did not rotate on its axis, the atmosphere would only circulate back and forth between the poles and the equator

www.oceanservice.noaa.gov

The Coriolis EffectThe Coriolis Effect

Because the Earth rotates on its axis, circulating air is deflected toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. This deflection is called the Coriolis effect.

www.oceanservice.noaa.gov

Wind PatternsWind PatternsWinds in atmosphere are driven by heat Winds in atmosphere are driven by heat energy from the sun.energy from the sun.

Equator is warmer than poles – more Equator is warmer than poles – more heat energy absorbed hereheat energy absorbed here

Less dense hot air risesLess dense hot air rises

Cooler air replaces it Cooler air replaces it

Wind is formed!Wind is formed!

Remember, winds to not travel straight, Remember, winds to not travel straight, they are bent by Coriolis Effectthey are bent by Coriolis Effect

If the ocean current is regarded as layered, then each deeper layer moves more slowly than the overlying layer.

Ekman TransportEkman Transport

Ocean GyresOcean Gyres

Created by wind-driven surface currentsCreated by wind-driven surface currents

Moderate climate by bringing warm water Moderate climate by bringing warm water north and cold water southnorth and cold water south

Ocean CirculationOcean CirculationIn some locations, large volumes of water may sink or rise.

Water sinks due to changes in temperature and salinity – this is known as an area of down-welling.

Down-welling brings gases from the surface to deeper layers.

Areas of upwelling come from currents that push deeper waters toward the surface.

Nutrients are much more plentiful in the deeper layers, so these areas of upwelling are beneficial for organisms in an upwelling area.

ThermoclinesThermoclines

Depth profiles for Depth profiles for salinity, salinity, temperature, and temperature, and densitydensity

What is a What is a thermocline and thermocline and how does it how does it develop?develop?

Seasonal vs. Seasonal vs. permanent permanent thermoclinesthermoclines

Temperature Temperature ProfileProfile

• Stable water column = less Stable water column = less dense shallow and more dense dense shallow and more dense deeperdeeper

• Unstable water column = Unstable water column = surface water sink and mixes surface water sink and mixes with deeper waterwith deeper water– DOWNWELLINGDOWNWELLING– Polar regions in winterPolar regions in winter

Ocean MixingOcean Mixing• These two water masses originate at the These two water masses originate at the

surface in the extreme North and South surface in the extreme North and South Atlantic, then sink and spread along the Atlantic, then sink and spread along the bottom.bottom.

Thermohaline Thermohaline CirculationCirculation

• The movement (circulation) of water in The movement (circulation) of water in the ocean over great distances that is the ocean over great distances that is driven by changes in densitydriven by changes in density

• Changes in density determined by Changes in density determined by temperature and salinity.temperature and salinity.

• ““FingerprintFingerprint”” of the water mass is how of the water mass is how currents are trackedcurrents are tracked

Circulation of the Circulation of the OceanOcean• The Great Ocean Conveyor – Global The Great Ocean Conveyor – Global

current pattern Deep circulation of the current pattern Deep circulation of the oceans is part of the global pattern known oceans is part of the global pattern known as great ocean conveyor. This constantly as great ocean conveyor. This constantly replenishes the oxygen supply to the replenishes the oxygen supply to the depths.depths.

WavesWaves

- Dependent upon the wind – longer and faster wind = larger wave- Water particles do not move along with a wave but instead move in circles. When under the crest they move up and forward with the wave, then they are pulled back down. As wave after wave passes, the water and anything floating in or on it moves in circles.

WavesWaves• As waves near the shore (shallower water), the bottom of the As waves near the shore (shallower water), the bottom of the

wave wave ““dragsdrags”” the bottom. the bottom.

• Forces waves to slow and move closer together (short Forces waves to slow and move closer together (short wavelength)wavelength)

• The The ““dragdrag”” causes the wave crest to fall over - we call this a causes the wave crest to fall over - we call this a wave break. The wave break. The surfsurf caused from breaking waves displaces caused from breaking waves displaces lots of sand which affects the organisms living there. lots of sand which affects the organisms living there.

• Influence of the bottom causes the particle motion to flatten Influence of the bottom causes the particle motion to flatten out into a back and forth movement known as surgeout into a back and forth movement known as surge

Fetch - the span of open water over which the wind blows

Fetch is important in determining the size of waves

Wind starts the wave which eventually settles out into a swell as it gets farther from the source of wind.

WavesWaves

What kind of waves are these?

TidesTides• Gravitational pull of the moon

and sun and by the rotations of the earth, moon, and sun.

• The moon and earth are held together by gravitational attraction. The moon’s gravitational pull is strongest on the side of the earth closest to the moon.

• Centrifugal force produced by the earth’s motion causes water to bulge outward, away from the moon.

• On the side of the earth closest to the moon, the gravitational pull overcomes the centrifugal force and pulls the water into a bulge toward the moon.

How does a grunion (Leuresthes tenuis) use the tide?

Because the moon moves while the earth is rotating, a full tidal cycle takes 50 minutes longer than the 24 hrs it takes the earth to make a complete rotation.

TidesTides

1. Spring Tide - The tidal bulges are largest, and therefore the tidal range is greatest, when the moon and sun are in line - new and full moon.

2. Neap Tide - Tidal ranges smallest when moon and sun are puling at right angles, which occurs when the moon is in quarter.

TidesTides

Semidiurnal tides – 2 high tides and 2 low tide per day

Bay of Fundy

How tides work

TidesTides

Worldwide distribution of semidurinal (2H, 2L), mixed semidiurnal (2H and 2L of different heights), and diurnal (1H, 1L) tides.

TidesTides