Earth’s Resources

Chapter Fifteen: Soil and Fresh Water Resources 15.1 Soil 15.2 Water Resources

Investigation 15B How does surface water quality affect the surrounding ecosystem? Water Quality and Ecosystems

15.2 Water Resources All life on Earth depends on water. Because we seem to have so much water it is easy to take it for granted. Pure water is water that does not contain any dissolved minerals or ions.

15.2 What is in water? Typically, water contains a range of dissolved substances. These substances include both minerals— which are useful to organisms that live in water—and pollutants. What are pollutants?

15.2 Water quality at home Water is important to our health and way of life. The Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) regulate water quality.

15.2 Water quality at home Tap water with a lot of dissolved calcium and magnesium is called hard water. This water may also contain iron, zinc, and copper depending on where you live. If your water forms soapy suds easily it’s “soft water”.

15.2 Water quality at home Tap water may also be treated with sodium fluoride (to prevent tooth decay) and with chlorine (to kill bacteria).

15.2 Analyzing water quality The water that we use at home was once in a river, lake, pond, or under ground. Tests and procedures for testing water quality are important for protecting your health.

15.2 Water quality To learn about the water quality of a pond, first make careful observations. –“What does the pond water look like or smell like? –What animals and plants are living in the pond? –Where is the pond located? –Are there houses or farms nearby? –Is the pond near a factory?

15.2 Water quality We protect the health of freshwater ecosystems by testing the water. Common tests include: –temperature, turbidity, dissolved oxygen, pH

15.2 Water quality The turbidity test measures the cloudiness of water. If the water is too cloudy, sunlight is blocked, and pond plants do not grow well. The secchi disk is lowered into the water until the black and white panels are no longer visible.

15.2 Water quality The water temperature of a pond is measured three or more inches below the surface of the water. The higher the water temperature, the less oxygen there may be in the water for living things.

15.2 Water quality The pH scale ranges from 0 to 14. Pure water is pH 7 (neutral). Most organisms in ponds function best when the water pH is near 7.

15.2 Water quality Water quality is better when dissolved oxygen levels are high. Oxygen is needed by most organisms living in the pond.

15.2 Water quality Nitrates and phosphates are chemicals that can enter ponds from farms, fertilized lawns, or septic tanks. Excess nitrates or phosphates endangers the health of the pond ecosystem.

Biology Connection What exactly is a bog? In the simplest of words a bog is a type of wetland. Bogged Down in Resources

Activity Minerals are valuable to humans. In this activity, two methods of mineral extraction will be examined. Mineral Extraction