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