Chapter 3 CHEMICAL AND PHYSICAL FEATURES OF SEAWATER AND WORLD OCEANS

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water All matter is made of atoms Elements are make from one kind of atom

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water A molecule is two or more different atoms combined Example: water Water is a polar molecule ; one end is positively charged and the other is negatively charged

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water The Three States of Water Only substance on Earth to naturally exist in three states or phases. Weak hydrogen bonds form between to the positive end and the negative end of different water molecules

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water The Three States of Water Hydrogen Bonds Sank the Titanic The Titanic sank because it hit an iceberg - a chunk of ice floating on the surface of the ocean. The reason ice floats is because of hydrogen bonding.

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water The Three States of Water Hydrogen Bonds Associated with Basilisk Lizard (Jesus Lizard)

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water The Three States of Water Weak hydrogen bonds form between to the positive end and the negative end of different water molecules Liquid d=1380&mid=57 d=1380&mid=57 Solid d=1381&mid=57 d=1381&mid=57

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water The Three States of Water Solid GasLiquid

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water The Three States of Water Solid water molecules pack close together & locked in fixed three dimensional pattern  Becomes more dense until about 4°C (get less dense) & expands  When water freezes in fresh and marine water the ice forms on top allowing organisms to live underneath the ice  When marine water freezes it acts like an insulator to stop freezing all the water

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water Heat and Water Bonds must be broken before molecules can begin to move around  Melts at higher temperature & absorbs a lot of heat when it melts (high latent heat of melting) and great deal of heat must be removed to freeze it

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water Heat and Water Melting ice, added heat breaks more hydrogen bonds than increasing molecular motion  Mixture of ice & water is 0°-adding heat goes into melting the ice not raising temperature  High heat capacity -marine organisms not affect by temperature changes in atmosphere & latent heat of evaporation

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water Water as a Solvent Dissolve more things than any other natural substance (universal solvent) especially salts  Salts made of opposite charged particles and conducts electricity Single atoms or groups of atoms  In water, strong ion charges attract water molecule, water molecules surround the ions and pull them apart (dissociation)

3.1 THE WATERS OF THE OCEAN The Unique Nature of Pure Water Water as a Solvent  In water, strong ion charges attract water molecule, water molecules surround the ions and pull them apart (dissociation)

3.1 THE WATERS OF THE OCEAN Seawater Characteristics due to nature of pure water & materials dissolved in it Dissolved solids due to chemical weathering of rocks on land & hydrothermal vents

3.1 THE WATERS OF THE OCEAN Seawater Salt Composition Sodium chloride account for 85% of all solids dissolved Salinity is total salt dissolved in seawater  Number of grams left behind when 1000 grams evaporated  If 35 grams left then 35 parts per thousand or 350/00 or 35 psu (practical salinity units)

3.1 THE WATERS OF THE OCEAN Seawater Salt Composition Rule of constant proportions states that the relative amounts of various ions in seawater are always the same  Differences in salinity results from removal (evaporation) and addition (precipitation) of water Rarely have to deal with changes in ratio of ions as result easier to control salt & water balance

3.1 THE WATERS OF THE OCEAN Seawater Salt Composition Average salinity is 35 psu and between psu in open ocean Dead Sea

3.1 THE WATERS OF THE OCEAN Seawater Salt Composition Red Sea is 40 psu Baltic Sea is 7 psu Why is Red Sea salinity so high and the Baltic Sea so low?

3.1 THE WATERS OF THE OCEAN Seawater Salinity, Temperature, and Density Density – mass per unit volume (D=m/v) Get denser as it gets saltier, colder, or both -2° to 30°C  temps. below zero possible because saltwater freezes at colder temps.

3.1 THE WATERS OF THE OCEAN Seawater Salinity, Temperature, and Density Density controlled more by temperature than salinity  There are exceptions therefore salinity & temp need to be measured to determine density

3.1 THE WATERS OF THE OCEAN Seawater Dissolved Gases O 2, CO 2 and N 2 in atmosphere & sea surface Gas exchange happens between the surface & atmosphere Dissolved gas concentration higher in cold water, lower in warm water

3.1 THE WATERS OF THE OCEAN Seawater Dissolved Gases Amount of oxygen in water is affected by photosynthesis & respiration Most oxygen is released into the atmosphere  More susceptible to oxygen depletion than atmosphere 80% of gases is carbon dioxide

3.1 THE WATERS OF THE OCEAN Seawater Transparency Sunlight can penetrate, but it’s affected by the material suspended in the water Important to the photosynthetic organisms Runoff makes coastal waters less transparent than deep blue waters of open ocean

3.1 THE WATERS OF THE OCEAN Seawater Pressure 压力 On land, organisms are under 1 atm at sea level Marine organism have the pressure of the atmosphere & water

3.1 THE WATERS OF THE OCEAN Seawater Pressure With every 10m increase depth another atm is added

3.1 THE WATERS OF THE OCEAN Seawater Pressure As atms increase gases are compressed  Organism have air bladders, floats and lungs that shrink and collapse  Limits depth range, some organism are injured when brought to the surface  Submarines & housing must be specially engineered to withstand pressure

3.2 OCEAN CIRCULATION =DQBPVNZ5nlfNZmzO0OgIrQhttp:// =DQBPVNZ5nlfNZmzO0OgIrQ

3.2 OCEAN CIRCULATION Throughout depths of ocean are currents Move and mix oceans waters Transport heat, pollutants and organisms

3.2 OCEAN CIRCULATION Surface Circulation Driven by the wind Wind is driven by heat from sun Winds and currents influenced by Coriolis effect.

3.2 OCEAN CIRCULATION Surface Circulation The Coriolis Effect Because Earth is rotating anything that moves over the surface tends to turn a little rather in a straight line Deflects large-scale motions like winds and currents to the right in Northern Hemisphere and to the left in Southern Hemisphere.

3.2 OCEAN CIRCULATION Surface Circulation Wind Patterns Winds driven by heat energy from sun

3.2 OCEAN CIRCULATION Surface Circulation Wind Patterns Trade winds -warmer at equator Wind at equator becomes less dense and air from Adjacent areas gets sucked in to replace it creating winds Wind bent by Coriolis Effect Approach equator at 45° angle where there is no land Steadiest winds

3.2 OCEAN CIRCULATION Surface Circulation Wind Patterns Westerlies at middle latitudes move in opposite direction Polar easterlies at high latitudes most variable winds

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents Direction of wind currents

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents Produce Ekman transport upper part of water column moves perpendicular (90 o ) to wind direction to right N. Hemisphere & left in S. Hemisphere

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents Global wind patterns and the Coriolis effect produce gyres (+sun’s heat & gravity) Gyres large circular systems of ocean currents

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents West side of gyres carry warm water to higher latitudes while cold current flow on eastern sides

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents West side of gyres carry warm water to higher latitudes while cold current flow on eastern sides

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents West side - warm waterEast side – cold Giant thermostat warming the poles & cooling tropics Tropical organisms like corals tend to extend into high latitudes on the west sides of the oceans Cold loving organisms like kelp grow closest to equator on eastern shores

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents El Niño Pacific Ocean Southeast trade winds slacken or cease Cool, nutrient-rich water within the Peru Current prevented from moving up to replace warm surface water

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents El Niño No nutrient-rich water = no plankton, a major source of food for fish, dies off Major disruption of the ecosystem Also alters jet stream path in the Northern Hemisphere Causes unusual increase in precipitation.

3.2 OCEAN CIRCULATION Surface Circulation Surface Currents El Niño Occurs about 14 times in a century Named El Niño (“the Child,” referring to the baby Jesus) because it usually begins around Christmas.

3.2 OCEAN CIRCULATION Thermohaline Circulation and the Great Ocean Conveyor Ocean water stratified Cold more dense on the bottom & warmer less dense on top

3.2 OCEAN CIRCULATION Thermohaline Circulation and the Great Ocean Conveyor The Three-layered Ocean 0 Surface layer or mixed layer 100 to 200m thick Mixed by wind, waves and currents Sometimes in summer & spring in temperate & polar waters sharp transition to cooler water (thermoclines)noticed by divers

3.2 OCEAN CIRCULATION Thermohaline Circulation and the Great Ocean Conveyor The Three-layered Ocean Intermediate layer/ 中间层 depth of 1000 to 1500m Main thermocline rarely breaks down & in open ocean

3.2 OCEAN CIRCULATION Thermohaline Circulation and the Great Ocean Conveyor The Three-layered Ocean Deep or bottom layers/ 深或底层 Below 1500 m typically less than 4°C

3.2 OCEAN CIRCULATION Thermohaline Circulation and the Great Ocean Conveyor Upwelling 上涌 occurs where Ekman transport moves surface waters away from the coast; surface waters are replaced by water that wells up from below. Where Ekman transport moves surface waters toward the coast, the water piles up and sinks in the process known as coastal downwelling 下行.

3.2 OCEAN CIRCULATION Thermohaline Circulation and the Great Ocean Conveyor The global ocean conveyor belt is a constantly moving system of deep-ocean circulation driven by temperature and salinity

3.3 WAVES AND TIDES Waves Caused by wind Parts of a wave: crest, trough, wavelength (, wave height, amplitude

3.3 WAVES AND TIDES Waves Waves

3.3 WAVES AND TIDES Waves Waves Wave crest moves up & forward Trough moves down and back Water particles do not go anywhere  Moves in a circle

ADD TO REVIEW GUIDE 26. Why do surfers like to go surfing after a big offshore storm? 27. What is the difference between sea, swell, and surf? 28. What causes tides? 29. What causes spring tides and neap tides. 30. Describe the varying types of tides that occur within a 24 hour period.

3.3 WAVES AND TIDES Waves Waves Fetch -span of open water Larger the fetch the bigger the wave

3.3 WAVES AND TIDES Waves

Seas Sharp peaks stretch over trough Move away get faster than speed of wind

3.3 WAVES AND TIDES Waves Swells Waves settle

3.3 WAVES AND TIDES Waves Surf Bottom forces water to move elongated ellipses Wavelength gets shorter Waves “pile up” becoming higher & steeper until they fall forward

3.3 WAVES AND TIDES Waves Water affected by mixture of waves Two crest adding to make a higher wave (wave reinforcement)  As high as ten stories Trough & crest combine & cancel out the wave (wave extinction)

3.3 WAVES AND TIDES Tides Influence marine organisms Organisms are exposed & submerged on shore Drive circulation of bays and estuaries, trigger spawning

3.3 WAVES AND TIDES Tides Why Are There Tides? Gravitational pull of sun & moon & rotation of Earth, moon, & sun Moon’s influence  Gravity strongest on side of earth closest - pulls water in ocean toward it  Opposite side furthest from moon - pull is weakest Earth’s rotation is like unbalanced tire (wooble) creates a centrifugal force - makes the oceans bulge out toward the moon & away from moon

3.3 WAVES AND TIDES Tides Why Are There Tides? Sun ½ as strong as moon because so far away  Full & new moon (sun moon in line) Tidal range (difference between high and low tide) is large Spring tides  First and third quarter Sun & moon at right angles partially cancel each other out – tidal range small Neap tides

3.3 WAVES AND TIDES Tides Why Are There Tides?

3.3 WAVES AND TIDES Tides Tides in the Real World Tides vary depending on location and the shape and depth of the basin

3.3 WAVES AND TIDES Tides Tides in the Real World Diurnal tides 1 high, 1 low Semidiurnal tides 2 highs, 2 lows Mixed semidiurnal tides 2 highs, 2 lows of different heights.

3.3 WAVES AND TIDES Tides Tides in the Real World East coast of N. America & most of Europe & Africa have semidiurnal tides (2 highs and 2 lows) West coast of USA & Canada mixed semidiurnal tide- successive tides of different height Diurnal ( 1 high and 1 low) rare on Antarctica and parts of Gulf of Mexico, Caribbean, & Pacific

3.3 WAVES AND TIDES Tides Tides in the Real World Tide tables give predicted time and height of high and low tides  Determined by local geology Weather like strong winds can cause water to pile on the shore creating higher tide than predicted