NCSCOS 3.0 Science 8

 What factors indicate the QUALITY of Water?  How do we know if the water in lakes, ponds, streams, etc., is healthy or not?  Why do lakes and ponds start to grow plants and eventually fill in and become meadows?

Three major classes of indicators used in evaluating water system health: 1. Physical 2. Chemical 3. Biological Water quality determines number & type of organisms in a water system

 Temperature – ◦ moderate to cool temperatures are healthy  Turbidity – ◦ amount of particles suspended in water ◦ low is healthy  Color – ◦ colorless is good

 High turbidity is BAD!  High turbidity can be result of soil particles, algae, microbes, etc. ◦ PROBLEMS: ◦ Algal blooms are rapid growth of algae from an excess of nutrients. They can block out the sun for the rest of the plant life underneath => less photosynthesis.  Turbid water can cause organisms to have trouble finding food  Sediment could clog gills of fish

 Erosion ->more sediment in water  Algae growth  Tides  Weather – hurricanes, winds, storms stir up sediment in water  Run-off from construction sites & agriculture  Waste/pollution into waterways

 Dissolved Oxygen (in parts per million, ppm) - ◦ high amount is healthy, so organisms can respire (breathe) ◦ Oxygen enters water by photosynthesis, winds, waterfalls, rapids, waves, etc. ◦ Low oxygen = HYPOXIA ◦ Little/No oxygen = ANOXIA ◦ Levels too high OR too low are problems ◦ DO levels are higher during daytime ◦ Colder water has higher DO levels

 pH = how acidic or basic (alkaline) ◦ Scale is 0 – 14, neutral = 7 ◦ Healthy water is between 6.5 – 8 ◦ Outside this range  # of organisms reduced

 Nitrates & Phosphates- ◦ nutrients used for growth by plants and algae ◦ found in fertilizers ◦ High levels indicate unhealthy water systems!! ◦ causes increase in plant life and growth of algal blooms ◦ Can cloud water & lower oxygen level ◦ High levels  Eutrophication = overgrowth of a body of water

 Water health is shown by number & variety of organisms living in it  Organisms used to monitor health= bio-indicators  EX: macroinvertebrates & microorganisms  EX: trout are bio-indicators of healthy water because they are a sensitive species  Can be:  1. Intolerant = cannot survive in polluted waters  2. Facultative = survive with difficulty  3. Tolerant = do well in polluted waters

 Signs of polluted/toxic waters: ◦ Change in population number ◦ Deformities ◦ Change in behavior ◦ Toxins in tissues ◦ High bacteria counts

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