A cycle is series of processes or events that continually repeat in some order. The water cycle, also known as the hydrologic cycle, is a never-ending process that results in the movement of water from one location to another. As water moves throughout the Earth’s surface and atmosphere, it undergoes several phase changes. Water changes phases from solid to liquid to gas as a result of changes in temperature. View this presentation to learn the parts and processes involved with the water cycle. Click the player button to begin.
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Sources of Water
Courtesy of the Environmental Protection Agency
Composition of Water on Earth
Freshwater is any water on Earth that does not contain salt. Freshwater is found in rivers, lakes, streams, the atmosphere, and the ground. As you can see from the image to the right, freshwater only makes up 2.5% of all the water on Earth. This means that salt water composes 97.5% of all water.
Did you know that most of the world’s freshwater supply is stored in the Earth’s polar ice caps? An estimated 1.7% of freshwater is stored in glaciers. That leaves groundwater as human’s major source of freshwater and the freshwater found in rivers, lakes, and our atmosphere is only a small percentage of the total freshwater available on Earth.
Freshwater Pollution
Fresh water is a very important resource that must be protected. Most organisms on the planet need fresh water for survival. Alarmingly, the Earth’s freshwater supplies are becoming a chemical cocktail. Human activities, such as waste disposal, are having a major impact on Earth’s freshwater supplies. Humans are guilty of polluting fresh water with biological waste (sewage), chemical pollutants, industrial waste, and chemicals from pesticides and fertilizers. Humans also add litter and trash to this already extensive list.
What you can do to help keep fresh water clean? You can help protect freshwater sources by conserving water at home. Conserving helps prevent water shortages and reduces the amount of contaminated water. You can use environmentally friendly products that do not have negative consequences for the environment. Take care not to overuse pesticides and fertilizers in your yard. These chemicals will runoff and empty into nearby water sources. Lastly, be sure not to litter. Trash and littler can enter storm drains and end up in nearby water sources.
Surface Water Review
Now that you have investigated surface water, practice what you have learned. In this non-graded activity, read the directions associated with each question to provide the correct responses. Click the player button to get started.