probes/kits used in testing the water quality 2014 group 4 project
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Probes/kits used in testing the water quality
2014 Group 4 Project
pH
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.
Factors that Affect pH Levels
Acidic rainfall
Algal blooms
Level of hard-water minerals
Releases from industrial processes
Carbonic acid from respiration or decomposition
Vernier pH ProbeStreams and lakes are often basic, with pH values between 7 and 8
Turbidity
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
Why Turbidity is important? Decreases photosynthetic rate Increases water temperature
Causing oxygen levels to fall.
VERNIER TURBIDITY PROBE
Vernier Turbidity Probe
Water is visibly turbid at levels above 5 NTU.
Drinking water ranges between 0.5 to 1 NTU.
Temperature
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.
Factors that Affect Water Temperature
Air temperature
Amount of shade
Soil erosion and increasing turbidity
Thermal pollution from human activities
Water Temperature influences
The amount of dissolved oxygen (DO)
Rate of plant growth
Metabolic rate of organisms
Vernier Temp. Probe
Dissolved Oxygen (DO)
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.
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 plantsFactors that
affect DO levels Temperature Aquatic plants Decaying organic
material in water
Stream flow pressure Human activities
Vernier DO Sensor
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.
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,
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.
Effects of high total solids
Can be harmful to aquatic organisms
Reduce water clarity (increased Turbidity)
Aesthetically unpleasing
Decrease photosynthetic rate
Increase water temperature
Vernier Conductivity Probe
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