Probes/kits used in testing the water quality

2. Probes/kits used in testing the water quality 2014 Group 4 Project

3. pH

4. Why is pH important? • pH is an important indication of water quality. Aquatic organisms are sensitive to the pH of their environment. • A pH range of 6.5 to 8.2 provides the optimum conditions for life of freshwater fish and bottom dwellers.

5. Factors that Affect pH Levels • Acidic rainfall • Algal blooms • Level of hard-water minerals • Releases from industrial processes • Carbonic acid from respiration or decomposition

6. Vernier pH ProbeStreams and lakes are often basic, with pH values between 7 and 8

7. Turbidity

8. TurbidityTurbidity is a measure of water’s lack of clarity. Water with high turbidity is cloudy, while water with low turbidity is clear. Sources of Turbidity • Soil erosion • Urban runoff • Industrial waste • sewage treatment effluent • particulates • Abundant bottom-dwellers • Microorganisms • decaying plants and animals

9. Why Turbidity is important?Decreases photosynthetic rateIncreases water temperatureCausing oxygen levels to fall. VERNIER TURBIDITY PROBE

10. Vernier Turbidity Probe • Water is visibly turbid at levels above 5 NTU. • Drinking water ranges between 0.5 to 1 NTU.

11. Temperature

12. Temperature • The temperature of a body of water influences its overall quality. • One important aspect of water temperature is its effect on the solubility of gases, such as oxygen.

13. Factors that Affect Water Temperature • Air temperature • Amount of shade • Soil erosion and increasing turbidity • Thermal pollution from human activities

14. Water Temperature influences • The amount of dissolved oxygen (DO) • Rate of plant growth • Metabolic rate of organisms

15. Vernier Temp. Probe

16. Dissolved Oxygen (DO)

17. Dissolved Oxygen • Oxygen dissolved in water is vital to the existence of aquatic organisms (cellular respiration) • The concentration of dissolved oxygen, DO, is an important indicator of the water quality.

18. How does Oxygen enter into the water?Diffusion of Oxygen from atmosphereAeration of water - water moves over rocks and debris - wind and wavesPhotosynthesis by aquatic plants Factors that affect DO levels • Temperature • Aquatic plants • Decaying organic material in water • Stream flow • pressure • Human activities

19. Vernier DO Sensor

20. Biochemical oxygen Demand (BOD) • BOD is a measure of the quantity of oxygen used by microorganisms (e.g., aerobic bacteria) in the oxidation of organic matter. • When nutrients and sunlight are overly abundant due to human influence, BOD is increased. • Oxygen consumed in the decomposition process robs other aquatic organisms of the oxygen they need to live.

21. Measuring Biochemical Oxygen Demand (BOD) • After 5 days of incubation in the dark at 20oC, the BOD bottles are unsealed and the final dissolved oxygen (DO) concentrations are read. • The difference between the initial and final concentrations,

22. Total Dissolved Solids • Solids are found in lake waters, both suspended and dissolved. • Suspended solids include silt, stirred-up bottom sediment, decaying plant matter, run offs or sewage effluent. • Dissolved solids include salts that yield ions such as sodium (Na+), calcium (Ca2+), magnesium (Mg2+), bicarbonate (HCO3–), sulfate (SO42– ), or chloride (Cl– ). • Total dissolved solids, or TDS, can be measured using a Vernier Conductivity Probe.

23. Effects of high total solids • Can be harmful to aquatic organisms • Reduce water clarity (increased Turbidity) • Aesthetically unpleasing • Decrease photosynthetic rate • Increase water temperature

24. Vernier Conductivity Probe