How Does Salinity affect Density in the Ocean?

What is Salinity? The total concentration of all dissolved inorganic solids Many salts dissolved in seawater NaCl, KCl

Why is the Ocean Salty? Weathering of rocks on land (carried by rivers into the ocean) Waves and surf erode coastal rocks and ocean bottoms Salt domes

How do you Measure Salinity? Measured in parts per thousand (ppt) Salinity is expressed by the amount of salt found in 1,000 grams of water. If the salinity of the ocean is 32ppt, it means there are 32 grams of salt in 1,000 grams of water *Hydrometer, refractometer

Ocean Salinity Varies very little overall, but there is a great deal of variation due to location Approx. 32ppt Lower salinity areas near rivers, areas with high amounts of rainfall High salinity areas with a lot of evaporation/lots of sun

How does the addition of salt affect water? Raises the boiling point Decreases freezing temperature Decreases heat capacity Slows evaporation Changes the density

Experiment How does salinity affect density in the ocean? Draw your observations Describe in words what you observe Answer the above question

How do fish adapt to changes in salinity?

Diffusion & Osmosis Diffusion Osmosis the tendency for a liquid, gas, or solute to flow from an area of high concentration to an area of low concentration Osmosis diffusion of water through a semipermeable membrane

Osmoregulators Organisms that have a regulation process that allows them to adjust the water concentration within their cells

Osmoconformers Organisms that cannot control their internal water concentration Their internal salinity rises and falls with the surrounding environment Example: marine invertebrates

Descriptors Euryhaline (“Eury” – wide, “haline” – salt) Can tolerate significant fluctuations Example: salmon & manatees Stenohaline (“Steno” – narrow) Cannot tolerate significant fluctuations Example: goldfish & grouper

Video Clips Dead Sea Dying Bowling Ball

How does Temperature Affect Density in the ocean?

Experiment What is the effect of temperature on density? How does this relate to the ocean? Draw your observations Describe in words what you observe Answer the above questions

What is the Effect of Temperature on Density? Water becomes more dense as it cools However, at about 4°C (right before the water freezes), water becomes less dense Ice Floats

Ocean Water Density Because temp and salinity affect water density, seawater stratifies (forms layers) Thermocline: an abrupt change in temp leading to 2 distinct layers Halocline: an abrupt change in salinity leading to 2 distinct layers Pycnocline: Thermocline and halocline together creating a boundary between layers of differing water density

Experiment: Layering Liquids Using what you have learned this week, can you use the 4 liquids to show stratified layers without mixing?

Key Red: Hot and Salty Blue: Cold and Salty Yellow: Hot and Fresh Green: Cold and Fresh

Conclusions: Answer the questions given to you on a separate piece of paper in complete sentences!

National Geographic Article Read the article individually Answer the questions as a group Nutrients in the Ocean: Phosphate, Nitrate, Silica, Iron…things typically dissolved in the ocean that plants and animals need to survive

Describe the importance of the ocean circulation pattern in the Southern Hemisphere. How do differences in ocean water density make the circulation pattern possible? According to the article, which has a greater impact on density in the ocean, salinity or temperature? Suggest a possible reason for this. Define Biological Productivity How might global warming affect the conveyor belt?