Ocean Water and Its Physical Properties Pressure Salinity Temperature Density

1. Ocean Water and Its Physical Properties • Pressure • Salinity • Temperature • Density

2. Pressure The pressure in a diver’s lungs at a depth of 10 meters is 2 atm and it decreases the volume and increases the divers density

3. Greater pressures under water compress air-filled spaces in the body a. lungs b. middle ear c. Eustachian tube to throat d. nasal sinuses

4. Diving bells were built in the 1600s to enable recovery of cannons and precious metals. Air compressors developed by the late 1700s allowed divers to stay under water longer and in deeper water. The compressors pump air into diving bells at a greater pressure than the surrounding water.

5. Uses of Commercial Diving Suits • Underwater inspection and non-destructive testing • Repairs of underwater structures • Marine salvage • All marine operations that require deep diving and/or • long bottom times • Rescue capacity for submersible operations • Platform inspections • Pipeline surveys • Scientific research

6. "Neufeldt-Kuhnke" diving suit, 1923 • Used in deep waters • Shell resists pressure up to a depth of 160 meters • Breathing system is managed in a closed circuit • Telephone lets the diver stay in contact with the surface • The grips serving as hands are mobile enough to accomplishment exacting tasks

7. Commercial Diving Suits • Atmospheric Hardsuit • Protect divers from pressure • maintained enough • dexterity to carry out work. • Operate at normal pressure- • the diver can descend • and ascend without long • decompression stops • Can operate at depths of • 1000 feet for up to six hours.

8. Jacques Cousteau and Emil Gagnan developed a device called a demand regulator. It is better known as scuba, which stands for: Self-Contained Underwater Breathing Apparatus

9. Scuba tank contains air under high pressure. As the diver descends, the regulator reduces air pressure to slightly above surrounding water pressure. Demand regulator in mouthpiece supplies air at the same pressure as the water, keeping the lungs at their normal size.

10. Barotrauma – AKA “The Bends”. As a diver descends, nitrogen gas is compressed and dissolved in the tissues. Rising too quickly results in rapid Decompression of the gases (bubbling), causing distension and damage to tissues.

11. Six factors that can cause decompression sickness. • stay down too long • dive too deep • come up too fast • make too many dives in too short a time. • exercise heavily during the dive • travel to altitudes above 2,500 meters too soon after diving What is the safe rate of ascent for divers to avoid decompression sickness? 0.3 to 1 meter per second (about the rate at which a bubble rises)

12. Salinity • Average salinity of ocean water is 35 parts/thousand or, 35 grams salt for every 1,000 grams of water. • Most common i0ns in seawater: chloride, sodium, & potassium • Increases in salinity makes seawater more dense, causing it to sink relative to fresher water.

13. Variables Affecting Ocean Salinity: • Increase in salinity results from: • Evaporation • Formation of sea ice • Decrease in salinity results from: • Precipitation • Runoff • Melting icebergs and sea ice

14. Variables Affecting Ocean Salinity: • High evaporation creates high salinity (low and middle latitudes) • River runoff and glacial melt waters decrease salinity • Icepack accumulation increases salinity of ocean water by removing fresh water from the ocean. • The affect of cold temperatures and high salinity creates dense, sinking water masses at high latitudes.

15. Halocline– Depth zone of sharp salinity change from low salinity to high salinity

16. Variables Affecting Ocean Temperature: • Latitude- related to angle of incidence of solarradiation and the duration of that solar radiation • Currents- Western Boundary Currents deliver warm surface waters to high latitudes, warming local climate • Depth- The thermocline marks the boundary between warm surface water and cold, deeper water. It is a marked temperature difference. The strongest effects are in the tropics. Thermoclines may not be present in very high latitudes.

17. Thermocline

19. Salinity and Temperature • Water that has high salinity freezes below 0°C (32°F) • This is why salt is used to melt the snow or ice on a road pavement. The saltier the brine, the lower its freezing point. • This is also why salt traditionally was added to the water–ice mixture used to make ice cream.

22. How do living organisms regulate salinity levels? Elodea cells in fresh water Elodea cells in 10% salt solution What do you notice about the cells of the elodea in the salt solution?

23. Diffusion • Molecules moving from areas of high concentration to areas of low concentration and eventually reaches equilibrium. • Ex: Occurs in the exchange of oxygen into muscles from the blood cells in the blood stream, or koolaid mix being stirred in water. Concentration all on one side of the membrane Equilibrium has been reached; same # of molecules on each side

24. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Cell Membrane • Selectively permeable: allows some substances to enter and leave the cell but prevents others from doing so. • Protects cell from losing common ions in seawater, as well as organic molecules (proteins) • Allows water and small molecules to pass

25. Osmosis • Diffusion of water across a selectively permeable membrane. • Also moves to reach equilibrium • If salt content is higher inside the cell, water will move in, and vice versa

26. Solutions can exist in 3 states: • Isotonic Solution • Hypertonic Solution • Hypotonic Solution

27. Example of Osmosis

28. How do living organisms regulate salinity levels? Osmoconformers • Organisms whose internal concentrations change as the salinity of water changes (narrow range) • They usually stay where the salinity of the water matches that of their fluids If placed in fresh water, cells will swell up and burst because of osmotic flow of water into their cells

29. Osmoregulators • Control internal concentrations to adapt to different salinities by adjusting the concentrations of solutes in their body fluids. (wide range) • Only the amount of solutes needs to be the same, not the exact same amounts • Ex: Redfish

30. Examples: • 1. Sharks – increase or decrease the amount of urea in their blood • 2. Dunaliella (one-celled plant) – increases or decreases the amount glycerol. Can go from nearly fresh water to 9 X’s the regular sea water.

31. Temperature • Greatly affect organisms • Metabolic reactions proceed faster at high temperatures and slow down as it gets colder • Reactions occur twice as fast with a 10°C rise in temperature

32. Ectotherms • Cold-blooded • As the temperature of surrounding water rises or falls, so does their body temperature and metabolic rate • Become quite sluggish in unusually cold water

33. Endotherms • Aka homeotherms • Warm-blooded • Mammals and birds that retain body heat as a by-product of muscle activity • Allows them to remain highly active regardless of water temperature, but it also used up large amounts of energy • Remarkably enough, this also includes some sharks.

34. Polar species have enzymes that work best at low temperatures, and cannot tolerate warm temperatures • The reverse is true of tropical species • Temperature plays a major role in determining where different organisms are found

35. SOFAR – Sound Fixing and Ranging Channel • Properties of sound vary with temperature and pressure differences • As temperature decreases, the speed of sound decreases, • As pressure (depth) increases, the speed of sound increases. • Sound waves bend, or refract, towards the area of minimum sound speed.

36. SOFAR – Sound Fixing and Ranging Channel Sound waves traveling through a thermocline bend downward. It is then refracted back upward as the speed of sound increases with increasing depth and pressure.

37. SOFAR – Sound Fixing and Ranging Channel This up-down-up-down bending of sound waves allows the sound to travel many thousands of meters without losing significant energy.

38. SOFAR – Sound Fixing and Ranging Channel We have learned that by placing hydrophones at just the right depth we are able to record sounds such as whale calls, earthquakes and man-made noise that occur many kilometers from the hydrophone. As a matter of fact, sometimes we can hear low-frequency sounds across entire ocean basins!. Image courtesy of Sounds in the Sea 2001, NOAA/OER.

39. Sound in the Sea!