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Grade 8 Science Unit 1: Water Systems on Earth Chapter 1 How do you use water? House Hold Use Personal Use Recreational Activities Water Distribution Only 3% of the Earth’s water is fresh water (no salt). 2/3 of this water is frozen in ice sheets. Therefore only 1% of the fresh water on Earth is available. Lithosphere: the solid rocky ground of the Earth’s crust. Atmosphere: the environment surrounding the Earth. Hydrosphere: All water on Earth. Including that in the lithosphere and atmosphere. Why do we not run out of water? The Water Cycle... The constant cycling of water through the processes of evaporation and condensation Water is constantly changing form (gas liquid) Driven by the sun’s energy Ocean Water vs. Fresh Water Three ways in which fresh water differs from ocean water are: Salinity Density Freezing point 1. Salinity The amount of salt dissolved in a specific amount of water. * salt comes from dissolved solids in the ground and volcanoes. 2. Density The amount of mass of a substance in a certain unit volume. How tightly packed together the material is in a substance. The Dead Sea 3. Freezing Point The temperature at which a liquid freezes. Table Fresh Water Salt Water Salinity Less salt More salt Density Less dense More dense Freezing point Higher (0˚C) Lower (-1.9˚C) Scientists who study water... 1. Hydrologist: A person who studies Earth’s water systems and helps to find solutions to problems of water quality and quantity. 2. Oceanographer: A person who studies all aspects of the ocean. They are concerned with the biology, geology, physics, and mathematics of the ocean. Sources of Fresh Water Ground water 2. Glaciers 3. Drainage basins 1. 1. Ground water: Precipitation that falls on land and sinks out of sight. Sinks through pores in rocks until it reaches bedrock where it pools. Drilling to these pools make wells. Ground Water 2. Glaciers: A moving mass of compressed snow and ice. Found in areas where it is so cold the snow remains all year. Glaciers in mountains and on the continent of Antarctica Glaciers are reservoirs (store fresh water) They release the water during the hot summer months. They give us information about the Earth’s past climates. Water trapped in glacial ice The Ice Age Earth has had at least 7. Most recent: 120 000 years ago -11 000 years ago. Covered from the Arctic to as far south as the Great Lakes! The environment was colder and a lot of plants and animals went extinct. Glaciers and Global Warming In the last 100 years the average surface temp. Has increased by 0.5oC. The world’s glaciers are melting at a quicker pace than ever before. Receding Athabasca Glacier in Alberta It has receded 1.5 km since 1843. What does this mean? Ocean waters may rise Flooding 3. Drainage Basins (aka. Watershed) An area of land from which water drains into a body of water (ex: river, pond, lake or ocean). There are many small drainage basins within a larger basin. Placemat Activity! List or draw the species found in freshwater environments Freshwater Environments: Lakes and ponds Wetlands Rivers and streams Estuaries P. 90-93 Saltwater Environments: Pelagic zone (the water column) Benthic zone (the ocean floor) P. 94-95 Species examples Vertebrates: Invertebrates: Microorganisms: Plants: Abiotic (non-living) factors that affect plant and animal distribution: 1. Temperature Different species tolerate different temperatures. Lower temperature means better water quality. 2. Dissolved Oxygen Colder water contains more dissolved oxygen (better quality). Dissolved oxygen levels should be at least 5mg/L for good water quality. 3. Phosphates Essential nutrient for living things BUT too much (from pollution) can be detrimental. Phosphate levels should be less than 10μg/L (micrograms/L) for good water quality. 4. Increased acidity Organisms have an acidity comfort-level and can die if the water becomes too acidic. pH should be between 5 and 8.5 (on a scale of 1-14) 5. Turbidity – Cloudiness of the water (how much dirt is stirred up) can affect fish's ability to take up oxygen from the water. High turbidity (very cloudy) means low water quality. 6. Pollution Point sources (specific source) ex: landfill leak, factory waste water Non-point sources (many sources) ex: pesticides, runoff from city streets 7. Upwelling (marine only) Vertical movement of water from the ocean floor caused by wind on the surface. Stirs up nutrients 8. Ocean Currents (marine only) Currents affect on what lives where, temperature, nutrients, and other factors. 9. Salinity The saltier the water is, the less plants and animals will be able to survive in it. This creates poor-quality ocean water (e.g. the Dead Sea).