1 / 35

Ocean Water

Ocean Water. Earth Science Ch. 15. 15.1 The Composition of Seawater. Seawater consists of about 3.5% dissolved minerals that are collectively called salts. Salinity: solid material dissolved in water. Salinity is the ratio of the mass of dissolved substances to the mass of the water sample.

kennethwilson
Download Presentation

Ocean Water

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ocean Water Earth Science Ch. 15

  2. 15.1 The Composition of Seawater • Seawater consists of about 3.5% dissolved minerals that are collectively called salts. • Salinity: solid material dissolved in water. • Salinity is the ratio of the mass of dissolved substances to the mass of the water sample. • Salinity is expressed in parts per thousand (0/00). • The average salinity of seawater is 350/00 • Most of the salt in seawater is NaCl. • Cl: 55%, Na: 31%, Other elements: 14%

  3. Sources of Sea Salts • Chemical weathering of rocks on the continents. The salts enter the ocean by runoff • Volcanic eruptions • Processes that decrease salinity by adding fresh water • Precipitation • Runoff from land • Melting of icebergs and sea ice • Processes the increase salinity by removing fresh water • Evaporation • Formation of sea ice

  4. Ocean Temperature Variation • The ocean’s surface water temperature is affected by the amount of solar radiation received, which is primarily due to latitude. • The angle of the sun’s rays at different latitudes affects the intensity of solar radiation. • Higher latitudes (near the poles) have lower surface temperatures because of the lower angle of the sun’s rays. • Lower latitudes (near the equator) have higher surface temperatures because of the higher angle of the sun’s rays.

  5. Surface water generally have higher temperatures than deeper waters. • Low latitudes • temperatures are high near the surface • The temperature decreases rapidly with depth. • This area of rapid decrease in temperature is called the thermocline

  6. High latitudes • the temperature of the water at the surface is similar to that in deep water. • Ocean water at high latitudes has no themocline. • Water that has no thermocline is called isothermal.

  7. Ocean Density Variation • Density differences cause a layering effect in oceans. • Seawater density is affected by 2 main factors: salinity and temperature • An increase in salinity increases seawater density. Increases in salinity increase buoyancy. • An increase in temperature decreases seawater density. • Of the 2 factors, temperature has a greater influence on density. • Cold water with high salinity would have the greatest density.

  8. Density of ocean water varies with depth. • Low latitudes • density dramatically rises with depth in an area is called the pycnocline. • High latitudes • density is similar throughout the water column. There is no pycnocline.

  9. General patterns in ocean water • Temperature • Decreases with depth • Due to lack of solar energy • Thermocline: largest decrease • Salinity • Decreases with depth • Due to less evaporation • Halocline: largest decrease • Density • Increases with depth • Due to surrounding water pressure • Pycnocline: largest increase

  10. Oxygen • Decreases with depth due to lack of photosynthetic organisms and consumption of oxygen by organisms at the surface • Dissolved Nutrients • Decreases with depth due to use by organisms at the surface • Solar Energy • Decreases with depth due to lack of sunlight • Life • Decreases with depth due to lack of oxygen and nutrients available

  11. Ocean Layering • The ocean is layered according to density. • Low density water is found near the surface and high density water is found below. • The highest density water is found at the greatest ocean depths. • The open ocean has a 3 layered structure: • Shallow surface mixed zone • Higher temperatures and mixing by waves and currents • Transition zone • Temperature drops quickly • Deep zone • No sunlight, freezing, high density

  12. Layering only occurs in low latitude regions. • In high latitude regions cold, high-density water forms at the surface, sinks, and forms a deep ocean current that travels toward the equator. • The water at the equator moves toward the higher latitudes by surface currents which are generated by winds. • This entire process is caused by convection • Cools – sinks – heats – rises

  13. 15.2 Diversity of Ocean Life • The success of marine organisms in the ocean depends on 3 factors: • Ability to avoid predators • Ability to find food • Ability to cope with challenges of their environment

  14. Classification of Marine Organisms • Marine organisms can be classified according to where they live and how they move. • They are classified as either: • Plankton – floaters (algae, bacteria, small animals) • Nekton – swimmers • Benthos – bottom dwellers (sea stars, crabs) • Most marine organisms live in the sunlit surface of the ocean where photosynthesis is possible. • Photosynthesis • H2O + CO2 + sunlight = O2 and C6H12O6 • Organisms that undergo photosynthesis provide food and produce oxygen. • Algae are an important source of oxygen

  15. Hydrothermal vents • Found along the mid ocean ridge • Water very hot and saturated with minerals • The precipitation of the minerals gives the water the appearance of black smoke • Chemicals from the vents are an energy source for bacteria • The bacteria produce sugars and food that enable them and other organisms to survive in this extreme environment

  16. Marine Life Zones • 3 factors are used to divide the ocean into distinct marine life zones: • Availability of sunlight • Distance from shore • Water depth

  17. Availability of sunlight • The part of the ocean into which sunlight penetrates is called the photic zone • The photic zone is the area where light is strong enough for photosynthesis to occur. • Phytoplankton which produce food that feed most ocean life are found in this zone

  18. Distance from shore • Intertidal zone • Region between high and low tides • Very harsh place to live due to changing conditions • Neritic zone • Covers the continental shelf • Shallow enough for sunlight to reach the ocean floor • Large number of species • Oceanic zone • Deep ocean • Lower levels of nutrients and smaller populations

  19. Water depth • Pelagic zone • Open ocean of any depth • Animals swim or float freely • Benthic zone • Any sea bottom surface • Animals that attach to, crawl upon, or burrow into the seafloor • Abyssal zone • Includes the deep ocean floor • Extremely high water pressure, constantly low temperatures, no sunlight, and sparse life.

  20. 15.3 Ocean Productivity • Primary productivity • Production of organic compounds from inorganic substances through photosynthesis or chemosynthesis • Two factors influence a region’s photosynthetic productivity: nutrients and sunlight • Primary producers need nutrients such as nitrogen, phosphorus, and iron • The most abundant marine life exists where there are ample nutrients and sunlight

  21. Oceanic feeding relationships • Phytoplankton, plants, and bacteria are the main oceanic producers • Only a small percentage of energy taken in at any level is passed on to the next level because energy is lost as heat at each level • The producer’s biomass in the ocean is much greater than the biomass of top consumers

  22. Trophic levels • Chemical energy stored in ocean producers is transferred to the other organisms through feeding • Zooplankton are herbivores that consume phytoplankton • Larger herbivores feed on brown algae and marine plants that grow near the shore • The herbivores are eaten by carnivores • Each of these feeding stages is called a trophic level

  23. Transfer efficiency • The transfer of energy between trophic levels is very inefficient • Only 2% of the light energy absorbed is stored as chemical energy and made available to the first trophic level • After the first level only about 10% is available for the next level

  24. Food chains and food webs • A food chain is a sequence of organisms through which energy is transferred starting with the primary producer, then the herbivore, then the consumer • More often than food chains, a food web is formed where the consumers can feed on a number of different animals, each of which feeds on a variety of organisms • Food webs show how the success or failure of one population could affect other populations

  25. How Does El Niño Work? • In normal years, the winds tend to blow from east to west across the waters of the tropical Pacific. The easterly winds push the surface waters westward across the ocean. In turn, this causes deeper, colder waters to rise to the surface. This "upwelling" of deep ocean waters brings with it the nutrients that otherwise would remain near the bottom. The fish populations living in the upper waters are dependent on these nutrients for survival. • During El Niño years, the winds weaken, causing the upwelling of deep water to cease. The consequent warming of the ocean surface further weakens the winds and strengthens El Niño. As the ocean warms, the warmer water shifts eastward and so do the clouds and thunderstorms that produce heavy rainfall along the equator. This results in changes in jet streams (winds aloft), which lead to dry conditions in Indonesia and Australia, and floods in Peru and Ecuador. El Niño events occur on average every 3 to 5 years.

  26. http://faculty.washington.edu/kessler/TALKS/ENSO-AMSteachers2.pdfhttp://faculty.washington.edu/kessler/TALKS/ENSO-AMSteachers2.pdf

More Related