Indicators of Water Quality

1. Indicators of Water Quality

2. Indicators • Water is seen as “good quality” or “bad quality” based off of several criteria • These criteria indicate the health of the water • Includes turbidity, pH, dissolved oxygen, temperature, nitrates, and bio-indicators

3. Definition: Turbidity • Turbidity: measure of the degree to which water looses its transparency due to the presence of suspended particulates This is a river with high turbidity 

4. Levels: Turbidity • Ideal level: 1 NTU (Nephelometric unit) • High level: 5 NTU

5. Causes: Turbidity • Causes of increased turbidity: Increased levels of phytoplankton sediment from erosion, re-suspended sediments from the bottom (stirred by bottom dwellers), waste discharge, algae growth, and urban runoff

6. Results: Turbidity • Results of high turbidity: High turbidity increases the absorption of sunlight thus making the water warmer. Warmer water has lower levels of dissolved oxygen causing fish and larvae to die

7. Definition: pH • pH: the acidity of the water (presence of hydrogen ion) • 07 is acidic • 7 is neutral • 7 14 is basic

8. Levels: pH • Surface Freshwater: 6.0 9.0 • Swamps: as low as 4.3 • Salt Water: 8.1 but as low as 7.7

9. Causes: pH • Causes of changes of pH: • Natural conditions (especially in swamps), dumping of waste (batteries) and farm runoff (lime)

10. Results: pH • Results of changes of pH: • A change in pH by 2 units results in a water system having 100 times a difference in acidity • Most aquatic life cannot withstand water outside the optimum pH thus resulting in death

11. Definition: Dissolved Oxygen • Dissolved Oxygen: the oxygen dissolved in the water

12. Levels: Dissolved Oxygen • Average level: 9.0 ppm (parts per million) • Must be 4-5 ppm to support diverse population of fish

13. Causes: Dissolved Oxygen • Causes of changes in dissolved oxygen: turbulent actions (waves, rapids), water depth, and plant growth

14. Results: Dissolved Oxygen • Results of changes in dissolved oxygen: • When DO drops too low, fish die • When DO is high, the water actually tastes better but can corrode water pipes

15. Definition: Temperature • Temperature: the measure of average kinetic energy

16. Levels: Temperature • Low: cannot be tolerated below 32 degrees F • High: only rough fish can tolerate temperatures above 97 degrees F

17. Causes: Temperature • Causes of change in temperature: source of water, time of year, suspended sediment, depth of water, and shade from shoreline vegetation

18. Results: Temperature • Results of changes in temperature: changes in temperature can make aquatic life susceptible to disease and at extreme levels can result in death

19. Definition: Nitrates • Nitrates: compound that contains the nitrogen based polyatomic ion NO3 (Ex: Sodium Nitrate)

20. Levels: Nitrates • Drinking Water Max: 10 mg/L • Fish: Below 90 mg/L seems to have no effect on warm water fish

21. Causes: Nitrates • Causes of nitrates: • Fertilizer runoff (both farm and home), manure pits, leaks in septic systems, animal waste, and rain trapping car exhaust

22. Results: Nitrates • Results of presence of nitrates: • Nitrates can increase the plant production and fish population resulting in overcrowding • If algae increases due to nitrates, the pH levels decrease killing fish • Nitrates are converted to nitrites in humans (can kill children)

23. Definition: Bio-indicators • Bio-indicators: macroinvertibrates found living in water (they tend to remain in one place) that are sensitive to pollution

24. Levels: Bio-indicators • High level of variety: healthy water source • Small level of variety: poor water source (indicator of high levels of pollution)

25. Causes: Bio-indicators • Causes of changes in bio-indicators: Pollution that results in changes in pH, temperature, dissolved oxygen, or nitrate levels

26. Results: Bio-indicators • Results of few varieties of bio-indicators present: the lack of a large number of different varieties of bio-indicators is indicative of pollution