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Transcript
Introduction to the Hydrosphere Objective • Students will understand the components of the hydrosphere. • Students will know the composition of ocean water, the physical structure of the ocean, and how the ocean is important to humanity. Review: The Hydrosphere I • Hydrosphere: the combined mass of water found on, under, and over the surface of the Earth • Recall that the hydrosphere is connected to the other spheres of the Earth System • Can anybody come up with one way that the hydrosphere is connected to another sphere? Review: The Hydrosphere II • The Water Cycle describes how the hydrosphere is connected to the atmosphere, cryosphere, biosphere and lithosphere The World’s Water I • Most of the world’s water is in the ocean basins (97%) • A much smaller amount (3%) is freshwater • Only 1% of the freshwater is easily accessible The World’s Water II The Importance of Water I • • • • • • Water is a necessity for life on Earth (1) Organisms need it to live (2) Growing food (3) Transportation (4) Industry (5) Other uses Water is important to industry The Importance of Water II • Water use varies from country to country, poorer countries use water more for agriculture, and richer countries use water more for industry The Importance of Water III • The world's six billion people are already appropriating 54 per cent of all the accessible freshwater contained in rivers, lakes and underground aquifers. • By 2025 humankind's share will be 70 per cent • As the world continues to industrialize, water demand will likely increase The Importance of Water IV • Conflicts and wars have been fought over water rights • Middle East fighting over the rights to the Jordan River water • Water wars over Los Angeles water access in California • "If the wars of this century were fought over oil, the wars of the next century will be fought over water.“ - World Bank vice president (Ismail Serageldin), 1995 The Importance of Water V • Nonrenewable resources—Can’t be replaced in nature very quickly Vs. • Renewable resources—Can be replaced in nature very quickly, once you use up the resource, it’s gone • Do you think water is a renewable or nonrenewable resource? Explain Ocean Water I • Ocean water is commonly called “sea water” • Composed of the following: • (1) Dissolved gases (including oxygen and carbon dioxide) • (2) Dissolved nutrients (nitrates and phosphates) • (3) Dissolved solids (salts) • (4) Suspended solids Ocean Water II • Salinity: The measure of the amount of dissolved salts in seawater. • Salinity is usually measured in parts per thousand (ppt), 1 ppt is 0.1% • The salinity of seawater varies: • Where is the salinity the greatest? The least? Why? Ocean Water III • Density of freshwater = 1.0 g/cm3 • Density of saltwater = 1.02 g/cm3-1.03 g/cm3 • Which type of water sinks? • Freshwater / Saltwater Demonstration Ocean Water IV • Ocean water absorbs light, this heats up ocean water. However, some light is reflected. • Why does ocean water appear blue? • Blue wavelengths are absorbed the least by the deep ocean water and are scattered and reflected back to the observer’s eye • Why does ocean water appear black? • All light is absorbed by the water and little is reflected back. • Why does ocean water appear green? • Living organisms reflect green light Ocean Water V • The temperature of the ocean water decreases with depth, in the area called the thermocline (see the diagram) • There are a number of environments that are depth / temperature Three major layers: (1) Epipleagic zone dependent. We will (2) Thermocline zone (3) Bottom zone discuss these later. Ocean Water VI • Scientists have divided the ocean into five main layers. These layers, known as "zones", extend from the surface to the most extreme depths where light can no longer penetrate. These deep zones are where some of the most bizarre and fascinating creatures in the sea can be found. As we dive deeper into these largely unexplored places, the temperature drops and the pressure increases at an astounding rate. The following diagram lists each of these zones in order of depth. Fundamentals of Oceanography IA • Ocean: Large body of salt water • Five principle oceans in the world • These oceans cover over 70% of the surface of the Earth Fundamentals of Oceanography IB • Some oceans are broken into southern / northern parts • Seas: Large body of water marked off by land boundaries • Examples: • North Sea • Weddell Sea • Ross Sea • Caribbean Sea Fundamentals of Oceanography II • What is oceanography? Oceanography is the study of the great bodies of salt water comprising all the oceans and seas that cover nearly threefourths of the surface of the earth, and the scientific study of the physical, chemical, and biological aspects of the so-called world ocean. The major goals of oceanography are to understand the geologic and geochemical processes involved in the evolution and alteration of the ocean and its basin, to evaluate the interaction of the ocean and the atmosphere so that greater knowledge of climatic variations can be attained, and to describe how the biological productivity in the sea is controlled. Fundamentals of Oceanography III • The ocean floor isn’t flat, there is underwater topography (called bathymetry) • Tectonics • Mid ocean ridge system • Sea mounts • Black smokers • White smokers • Fault zones • Trenches Fundamentals of Oceanography IVA • Mid ocean ridge extends for over 49,000 miles, a place where new ocean crust is forming Fundamentals of Oceanography IVB • The mid ocean ridge system is essentially a long chain of volcanoes, a place where magma comes to the bottom of the ocean floor • The ocean floor spreads apart away from the ridges Fundamentals of Oceanography V • Seamount: A mountain rising from the ocean seafloor that does not reach to the water's surface, and thus is not an island, extinct volcano • Can provide habitats for marine species that are not found on or around the surrounding deeper ocean bottom • Navigation hazards and good fishing Fundamentals of Oceanography VIA • Hot spot—A location on the Earth's surface that has experienced active volcanism for a long period of time • Hot spots are visible in ocean basins as a series of islands / seamounts (Hawaii) Fundamentals of Oceanography VIB • Hawaiian-Emperor Seamount Chain, which is a whole series of islands / seamounts formed from the Hawaii hot spot: Fundamentals of Oceanography VII • Black smokers: A type of hydrothermal vent found on the ocean floor • Unique ecosystems near both types of vents • Organisms around these vents don’t require sunlight to live, but chemicals - Possible extractable ore deposits • White smokers: White smokers are a type of hydrothermal vent that emits lighterhued minerals than black smokers. They are generally cooler too. Fundamentals of Oceanography VIIIA • Faults, which are zones where rocks are displaced (moved), can occur underwater, below oceans and/or seas • Tsunami: Is a series of waves created when a body of water, such as an ocean, is rapidly displaced • Causes of tsunamis: (1) Displacement along a fault, (2) Underwater volcanic eruption, (3) Underwater avalanche, (4) Impact of an extraterrestrial body • DID YOU KNOW? The largest tsunami recorded measured 210 feet, about 18 stories above sea level, when it reached Siberia's Kamchatka Peninsula in 1737. Fundamentals of Oceanography VIIIB • A tsunami struck multiple countries in Africa and Asia in 2004 due to an underwater earthquake • Seawalls are built to protect coastal cities from tsunamis • Tsunami warning network Watch tsunami videos Fundamentals of Oceanography IXA • Trench: A relatively deep, linear and narrow oceanic feature that is formed by plate subduction. • Deepest parts of the ocean floors • The deepest trench: Mariana Trench (10,739 m (35,787 ft)) • Chemosynthetic (turning chemicals into carbon) communities thrive in certain deep trenches areas Fundamentals of Oceanography IXB • The Puerto Rico Trench between the North American and Caribbean Plates: Ocean Currents I The major surface currents in the world’s oceans are caused by prevailing winds. The currents may be cold, as in the instance of the West Wind Drift, or warm, as the Gulf Stream. Currents circulate in paths called gyres, moving in a clockwise direction in the northern hemisphere and a counterclockwise direction in the southern hemisphere. Ocean Currents II • Density Current: Different densities caused by a difference in temperature and salinity. • Surface Current: Can move as fast as 100 km a day and effect the top 200 m of the ocean. Driven by winds. Ocean Currents III • Upwelling: The upward motion of ocean water. Cold water moves from the bottom to the surface. These waters are rich in nutrients and very productive for fisherman. High in oxygen. • Upwelling = good fishin’! Ocean Currents IV • Life in the oceans is not uniformly abundant. Because of the low ratio of surface water to deep water and the lack of seasonal nutrient enrichment, much of the open ocean is a watery desert, especially the tropical seas. The most productive areas are the coastal regions, areas of upwellings (see below), and the Arctic and Antarctic oceans • The rich Antarctic waters are pulled away from the shore and become part of the Antarctic Circumpolar Current, also known as West Wind Drift. This current, the strongest ocean current on earth, is partially diverted by the southern tip of South America, forming the Humboldt Current off the coast of Peru. As the surface water is pulled out by winds, the nutrient-rich deep water replaces it, aided by the absence of a continental shelf. This is an important upwelling region, and it supports an enormous amount of life. Copepods and opossum shrimp replace the krill of the Antarctic. Feeding on these crustaceans are immense schools of small fish that, in turn, are consumed by seabirds, replacing whales at the top of the food web. Ocean Currents V • The flow of ocean currents plays a dominant part in the climate of many of the Earth’s regions • The world’s oceans collect heat and transport it around the world Ocean Resources IA • Fishing is very important in provide world societies with protein • World total of 86 million tons of fish were captured in 2000 • It will be necessary to manage ocean fisheries in the coming years to make sure the number of fish caught never makes it to zero • Predictions are that the sea can yield only about 25 percent more than the present amount of organic food resources. Ocean Resources IB • Fisheries: is the name of the business of harvesting fish and other marine animals and plants in order to make a living. Fisheries include: (1) large industrial-scale operations with foreign fishermen who process their catch for export and commercial sales, (2) small-scale operations by local fishermen who primarily supply nearby markets, (3) aquaculture farms which raise marine animals and fish in a maintained environment, and (4) businesses that produce fish products. • Exclusive Economic Zone (EEZ): More than 90% of world marine fish catch comes from the 10% of the oceans closest to land. This area is included in the Exclusive Economic Zone (EEZ). The EEZ refers to the coastal waters that lie adjacent to the coast and extend 200 nautical miles offshore. Ocean Resources IC • Countries have exclusive rights within the EEZ Ocean Resources IIA • Petroleum resources can be found off of shorelines in oceans and/or seas • There are rock layers under sea/ ocean water that hold petroleum and trap it Simplified cross-section showing a slice through the geologic layers under the Gulf of Mexico Ocean Resources IIAA • Oil platforms are situated in waters off of coastlines, including in the Gulf of Mexico • These platforms are shut down when hurricanes approach 17 percent of the world petroleum production Ocean Resources III • The ocean is used for shipping products from one country to another • Large number of products traveling from China to the USA • Panama Canal expansion Ships can spill oil (or other chemicals) or can create noise pollution, adversely affecting the marine environment Ocean Resources IV • Tourism is also an important industry in the oceans • Eco-tourism Ocean Resources V • Tidal energy farms • A lot of wind energy can be harnessed by placing windmills out in seas and/or oceans. This is commonly called “offshore wind” Ocean Resources VI • Desalinization plants: Plants that remove excess salt and other minerals from water • Desalinization of ocean water is very important in the dry Middle East, and may be increasingly more important in the future, worldwide Ocean Resources VII • Mining operations are conducted in and under the ocean • Diamonds, gold, silver, metal ores, sand, salt, and gravel mines Climate Change & the Oceans Fun Fact • Did you know? If all the gold suspended in the world's seawater were mined, each person on Earth could have about 9 pounds of gold. References • • • • • • • • • • http://www.unesco.org/water http://www.worldwater.org http://www.loc.gov http://www.dictionary.com http://oceanexplorer.noaa.gov http://www.wikipedia.org http://marinebio.org http://www.mvtimes.com http://www.aip.org The Little Giant Book of Science Trivia