1. 2.1 Monitoring Water Quality

2. Overview How water quality is determined Biological indicators
Based off of the 5 main uses
Biological indicators
Microbes and aquatic invertebrates
Chemical factors that affect organisms
Dissolved oxygen, acidity, pesticides, heavy metals, nutrients, salts
Measuring chemicals and toxicity
ppm calculations
LD50

3. Question Is clear water an indicator of higher water quality?
Answer: not necessarily!
Lakes affected by acid rain are usually clear, but they are also inhabitable
When lake transparency decreases, the property values of the surrounding real estate (houses, cottages, etc.) also decreases

4. How is Water Quality Determined?
It depends on what the water is being used for
The 5 main uses of water are:
Human drinking water
Recreation
Livestock drinking water
Irrigation
Protection of aquatic wildlife

5. Biological Indicators
Microbes
Bacteria, viruses, and plankton
If present in large amounts, they may be harmful and additional water treatment may be required
Use up dissolved oxygen
Aquatic Invertebrates
Insects, crustaceans, worms, and mollusks
Do not cause illness, but can show the effects of pollution
e.g. some mayflies are sensitive to acidity and low dissolved oxygen

6. Chemical Factors that Affect Organisms (and Water Quality)
Dissolved oxygen
Acidity
Pesticides
Heavy metals
Nutrients
Salts

7. Dissolved Oxygen
Essential for aquatic life such as fish, insects, and microorganisms
Dissolved oxygen levels depend on:
Temperature
Turbulence due to wind, or the speed the water moves at
Amount of photosynthesis by plants and algae
The number of organisms using up the oxygen
The acceptable level for most living things is 5 ppm (parts per million) or 5 mg/L

8. Acidity Remember: rain and snow normally have a pH of about 5.6
Anything less is acidic
When this enters water systems, it lowers their pH
Most fish begin to disappear when the pH drops below 5.0
Acidic deposits become a problem when the soil and water do not contain natural bases to neutralize the acid
e.g. the Canadian shields
Spring Acid Shock: occurs after acids have built up in the ice and snow over the winter; once they melt during the spring, the water flows into our aquatic systems

9. Pesticides May remain in the environment long after they are needed
New pesticides are designed to only remain the environment for a single season
Can potentially lead to insect-resistance, leading to the development of new pesticides
This introduces other chemicals to the environment
Pesticides can enter our water systems
Seeing as we use multiple types of pesticides, although they enter the water systems in small amounts, their combinations can increase their overall toxicity (i.e. how poisonous they are)

10. Heavy Metals
Defined as metals that have a density of 5 g/cm3 (5 g per cubic centimeter) or more
5 or more times heavier than equal volumes of water!
e.g. copper, lead, zinc, mercury, cadmium, and nickel
May occur naturally in rocks, soil, and sometimes water
In their natural forms, they are generally not available to plants and animals
However...
They may also occur in the environment due to human activity
Acid rain can dissolve the lead in metal pipes
Cadmium is present in some fertilizers
Plants can take up these sources of heavy metals, and animals that eat these plants may experience some health effects as a result

11. Nutrients Nitrogen and phosphorus
Comes from sewage outfalls, and runoff from fertilized fields
Dissolved oxygen is affected by increases of nutrients in water
An increase in nutrients increases algae and plant life
Decomposing bacteria eat the plants and algae once they die
The population of bacteria increases due to the increase in food available, and as a result they use up more dissolved oxygen (decreasing it)
A decrease in dissolved oxygen kills many fish and insects

12. Measuring Chemicals: ppm
Chemicals in the environment are usually measured in ppm (parts per million) or mg/L (milligram per litre) - where 1 ppm = 1 mg/L
This means that one unit of an element or chemical can be found in one million units of solution
e.g. a single drop of food colouring in a half-full bathtub is about 1 ppm
In the example above, the food colouring would be the solute, and the water in the bathtub plus the drop of food colouring would be the solution
Let’s try an example

13. Suppose you add 10 mL of vinegar to 390 mL of water
Suppose you add 10 mL of vinegar to 390 mL of water. What is the concentration of vinegar in ppm?

14. Measuring Toxicity: LD50
Toxicity: how poisonous a substance is
LD50: the amount of a substance that causes 50% of a group of test animals to die if they are given that substance all at once
e.g. if the LD50 of a substance is 0.3 mg and a group of 400 test animals was given that dosage, how many animals would die?
200