Ocean Water

1. Spring 2014 Ocean Water

2. Properties of Ocean Water • Physical properties of ocean water • Temperature • Density • Color • Chemical Properties • Determine its composition • Enable the ocean to dissolve other substances

3. Properties of Ocean Water • Composition of Ocean Water • Salts enter the ocean from rivers and streams • Gases enter the ocean from rivers, streams, & directly from the atmosphere • Elements in Ocean Water • 95.6% pure water • 75 chemical elements • 6 most abundant: chlorine, sodium, magnesium, sulfur, calcium, & potassium

4. Properties of Ocean Water • Dissolved Gases • 3 most common • Nitrogen • Oxygen • Carbon dioxide • Higher temperature= less dissolved gases • Lower temperature= more dissolved gases • Exchange of gases between the atmosphere & the ocean is a constant thing

5. Properties of Ocean Water • Salinity • The number of grams of dissolved solid per volume of liquid • Called salinity most dissolved solids are salts • 78% of the dissolved salt in the ocean is NaCl (sodium chloride) • Increased by both evaporation & freezing • Salinity varies by depth • Because the ocean is constantly mixing the average salinity is similar all over the globe

6. Properties of Ocean Water • Temperature • Surface Temperture • Movement of water throughout the ocean thoroughly mixes the warmed surface water • Distributes heat downward (100m – 300m) • Temperature of this zone is relatively constant • Temperature decreases with increasing latitude • Poles have colder surface temp than the middle latitudes • Ice pack- floating layer of sea ice that covers the surface of the ocean in both the Arctic & Antarctic during parts of the year

7. Properties of Ocean Water • Temperature • Thermocline • Zone of rapid temperature change • Exists because water near the surface that is heated by the sun is less dense than the colder deeper water • Changing temperature or shifting currents may alter the depth or cause it to disappear completely

8. Properties of Ocean Water • Density • Mass of a substance per unit of volume • 2 factors affect the density of ocean water: • Salinity • The large amount of dissolved solids in ocean water makes it more dense than fresh water • Temperature • Water becomes more dense as it get colder ***Affects density more than salinity

9. Properties of Ocean Water • Color of Ocean Water • Color is determined by the way it absorbs or reflects sunlight • Only blue wavelengths tend to be reflected • Only the upper regions show color; the lower region is in total darkness

10. Life in the Ocean • Most marine organisms depend on 2 factors for their survival: • Essential nutrients available in ocean water • Sunlight

11. Life in the Ocean • Ocean Chemistry & Marine Life • Animals & plants living in the ocean help maintain the chemical balance of ocean water • Nearly all life is regulated by the life processes of plants • Elements nitrogen, phosphorus, & silicon are critical nutrients for the growth of plants

12. Life in the Ocean • Ocean Chemistry & Marine Life cont… • Marine plants & animals absorb & store the substances they need for life. • All of the elements necessary to marine life are consumed by marine plants & animals near the surface but released at great depths through decay • Upwelling- occurs when wind blows steadily parallel to the shore along a coastline, surface ocean water is moved farther offshore causing deep water to then move up

13. Life in the Ocean • Sunlight & Marine Life • All marine plants & animals require sunlight in addition to the nutrients from water • Plant growth is limited to the upper 100m of water • Plankton- free floating microscopic marine plants & animals • 2 main types of plankton • Phytoplankton- plants & other photosynthetic organisms • Zooplankton- non-photosynthetic animals • Nekton- eat plankton, forms of ocean life that swim • Benthos- organisms that live on the ocean floor

14. Life in the Ocean • Ocean Environments • 2 general environments • Benthic- bottom • Divided into 5 zones • Pelagic- water • Divided into 2 zones • **The amount of sunlight, temperature, & water pressure determine the distribution of marine life within these zones

15. Life in the Ocean • Ocean Environments • Benthic Environments • Intertidal zone- lies between low tide and high tide lines • Crabs, clams, mussels, sea anemones, & seaweed live here • Sublittoral zone- shallow & completely submerged; located on the continental shelf; contains the largest number of benthos • Sea stars, brittle stars, & sea lilies

16. Life in the Ocean • Ocean Environments • Benthic Environments • Bathyal zone- starts at the continental slope & ends at a depth of 4000m • Octopuses, sea stars, & brachiopods • Very little plant life • Abyssal zone- 4000m to 6000m of depth • Sponges, worms, & sea cucumbers • No light at all • Hadal zone- inside ocean trenches; deeper than 6000m • Virtually unexplored; life is sparse

17. Life in the Ocean • Ocean Environments • Pelagic Zones • Neritic zone- above continental shelves • Abundant sunlight, moderate temperatures, low pressure • Ideal for marine life • Much of the seafood & fish that we eat lives here • Oceanic zone- extends into the deep ocean & open ocean waters beyond the continental shelf • Divided into 4 zones based on depth • Epipelagic ,Mesoplagic, bathypelgaic, abyssopelagic • Marine life decreases with increasing depth

18. Ocean Resources • Fresh Water from the Ocean • 2 ways in which the need for fresh water can be met: • Fresh water now available can be conserved to avoid waste • Amount of available fresh water can be increased • Can be done by finding a way to convert ocean water to fresh water for a reasonable cost

19. Ocean Resources • Fresh Water from the Oceans • Desalination- the removal of fresh water from salt water • Distillation- heating ocean water to remove the salt • Problem: evaporating liquid water requires a large amount of expensive heat energy • Freezing • The first ice crystals that form are free of salt • Chunks of ice can be melted & used as fresh water • Use of membranes (reverse osmosis) • Allow water under high pressure to pass through while blocking the dissolved salts

20. Ocean Resources • Minerals from the Ocean • Nodules • Valuable source of manganese which is used making some types of steel • Also contain iron, copper, nickel, & cobalt • Problem: expensive & difficult to retrieve • Minerals • Salt • Magnesium • Bromine • Petroleum is the most valuable mineral found beneath the ocean floor • Most comes from the continental shelves • Productive offshore wells are located in the Gulf of Mexico, the North Sea, the Persian Gulf, & off the coasts of California, Alaska, & Australia

21. Ocean Resources • Food from the Ocean • Protein rich fish is an important part of the human diet • Aquaculture- farming of the ocean • Developing & raising species of marine animals & plants that yield large amounts of food • Successful in growing catfish, salmon, oysters, & shrimp

22. Ocean Resources • Ocean-Water Pollution • Oceans have been historically used as dumping grounds • Garbage, sewage, nuclear wastes • Productive coastal waters are in the most danger