Investigating the movment of water soil
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Title: The power of water |
Author: Cota |
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Subject: Science |
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Learning objectives: Rain drops strike the Earth with such force that they can break off fragments of rock and creat runoff. The amount of water absorbed by the ground is a measure of soil porosity. Water and disolved oxygen, amount of gaseous oxygen (O2) dissolved in an aqueous solution. Oxygen gets into water by diffusion from the surrounding air, by aeration (rapid movement), and as a waste product of photosynthesis. Water conductivity, is a measurement used to determine a number of applications related to water quality. |
Key Questions, Concepts, or Themes: Ground water Porosity dissolved oxygen water conducitivity |
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Stage 1: Rain Drops: Write the number 40 quadrillion on the board tell the students that this number represents the approximate number of liters of rain water that washes over the Earth and flows into the seas each year.
1) determining mineralization: this is commonly called total dissolved solids. Total dissolved solids information is used to determine the overall ionic effect in a water source. Certain physiological effects on plants and animals are often affected by the number of available ions in the water. 2) noting variation or changes in natural water and wastewaters quickly; 3) estimating the sample size necessary for other chemical analyses; and 4) determining amounts of chemical reagents or treatment chemicals to be added to a water sample.
Elevated dissolved solids can cause "mineral tastes" in drinking water. Corrosion or encrustation of metallic surfaces by waters high in dissolved solids causes problems with industrial equipment and boilers as well as domestic plumbing, hot water heaters, toilet flushing mechanisms, faucets, and washing machines and dishwashers. Indirect effects of excess dissolved solids are primarily the elimination of desirable food plants and habitat-forming plant species. Agricultural uses of water for livestock watering are limited by excessive dissolved solids and high dissolved solids can be a problem in water used for irrigation.
In an avergae rainfall, over 12 million raindrops fall on every 10,000m2 of lan or surrounding surface. 1. find out New York area or our school yard and we can calculate the number of rain drops that would fall in an hour?
2. Lab: Invetigate the movement of water in soil. Much of the water that reaches the Earth's surface drains into lakes, rivers, and streams. Addational water may evporate or it may filter down through the soil until it reaches an impermeable layer. This water collects in the air-filled spaces and the upper surface f this water-filled area is known as the water table. Water that collects beneath the surface of the Earth is known has ground water. Ground water is a vital source of fresh water, as are wells, reservoirs.
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Stage 2:
Total dissolved gas concentrations in water should not exceed 110 percent. Concentrations above this level can be harmful to aquatic life. Fish in waters containing excessive dissolved gases may suffer from "gas bubble disease"; however, this is a very rare occurrence. The bubbles or emboli block the flow of blood through blood vessels causing death. External bubbles (emphysema) can also occur and be seen on fins, on skin and on other tissue. Aquatic invertebrates are also affected by gas bubble disease but at levels higher than those lethal to fish. Adequate dissolved oxygen is necessary for good water quality. Oxygen is a necessary element to all forms of life. Natural stream purification processes require adequate oxygen levels in order to provide for aerobic life forms. As dissolved oxygen levels in water drop below 5.0 mg/l, aquatic life is put under stress. The lower the concentration, the greater the stress. Oxygen levels that remain below 1-2 mg/l for a few hours can result in large fish kills.
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Stage 3: Water conductivity: Conductivity is a measurement of the ability of an aqueous solution to carry an electrical current. An ion is an atom of an element that has gained or lost an electron which will create a negative or positive state. For example, sodium chloride (table salt) consists of sodium ions (Na+) and chloride ions (Cl-) held together in a crystal. In water it breaks apart into an aqueous solution of sodium and chloride ions. This solution will conduct an electrical current. |
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Homework: No homework in this class? |
Assessments: (attach/link copies) __ Group assessment __ Observation of process/student work __ Self-assessment by student __ Teacher generated assignment __ Written project __ Test/Quiz __ Other: ____________________________________ |
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