Pollution and Monitoring

5.1.1-5.1.3; 5.2.1-5.2.3;

2.2.1-2.2.2

In water,

of course!

What is Pollution?

• Pollution is the introduction of contaminants into an environment by human activity.

• Pollution can take the form of chemical substances

• Pollution can also be heat (thermal pollution), noise and light (More on this when we discuss the destruction of atmospheric ozone)

Types of Pollution

Types of Pollution

Types of Pollution

Effluent as Pollution• Effluent is an out flowing

of water (treated or untreated) into the environment

• In this case, effluent is out flowing from sewage or industrial waste– In some countries this can

even be raw sewage

• Companies may pay fees or taxes in order to discharge in the environment or to a sewer = Effluent Tax

Point Source Pollution

• The release of pollutants from a single, clearly identifiable site.

• Impact is more localized and blame is easily allocated.

• Ex?

Non-Point Source Pollution

• NPS pollution is the release of pollutants from numerous, widely dispersed origins

• Because it is hard to tell where the pollution is coming from, it is more difficult to fix and take legal action.

• Ex?

Temperature

• Human activities should not change water temperatures beyond natural seasonal fluctuations.

• “Good” temperatures are dependent on where the stream is located. – In a warm water stream temperatures should not

exceed about 32 degrees C– Cold water streams should not exceed about 20

degrees C• Often summer heat can cause fish kills in ponds. Why?

Aquatic Thermal Pollution• Large inputs of heated water from a single

factory or a number of factories using the same lake or slow-moving stream

• How else can rivers/streams get overheated?

Aquatic pH

• Changes in pH values in aquatic locations has an effect on the organisms living at that location.

• What would change the pH of a body of water?

• Since the majority of aquatic life has adapted to living in certain pH levels, large changes may cause these organisms to die.

Aquatic pH

• Aquatic bacteria can live in a pH level between 2 and 13

• Plants between 6 and 13

• Carp, catfish, bass, bluegill, snails, clams, mussels and trout can be found in pH levels between 6 and 9.

• How might this affect aquatic health?

Monitoring Pollution

• Can be:– direct measuring = recording the amount of pollutant in

environment)• Testing for nitrates and phosphates, amount of organic matter

or bacteria, and heavy metal concentrations (ie: mercury or lead)

– This can cause instability, and harm to the system and the health of the organisms within it.

– or indirect measuring = recording changes in an abiotic or biotic factor which are the results of the pollutants.

• Abioitic ex: dissolved oxygen (ie Biochemical Oxygen Demand)• Biotic ex: presence or absence of an indicator species =

Dissolved Oxygen

• Dissolved oxygen analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution

• How does oxygen get into water?

Dissolved Oxygen

Biochemical Oxygen Demand

• Biochemical Oxygen Demand or Biological Oxygen Demand (BOD) is a how fast bacteria use up oxygen in a body of water – Measures the amount of dissolved oxygen needed by

aerobic decomposers to break down the organic materials in a given volume of water

– So, the more organic pollutant (sewage) present…

– This decreases the amount of oxygen available to plants and fish!

Biological Oxygen Demand

The BOD Test– BOD measures mass (in milligrams)

of dissolved oxygen consumed per liter of water when the sample is incubated at a temperature of 20°C after five days in the dark.

• Why in the dark?

BOD Values?

• Most pristine rivers will have a 5-day BOD below 5 mg/L

• Moderately polluted rivers may have a BOD value in the range of 5 to 10 mg/L

• Municipal sewage that is efficiently treated would have a value of about 20-60 mg/L.

• Untreated sewage varies, but averages around 350 mg/L

• Cattle slurry is around 10,000 mg/L• Paper pulp mill is around 25,000 mg/L

Indirect Method using Biotic Index• A biotic index is a scale (1-10) that gives a

measure of the quality of an ecosystem by the presence and abundance of certain species living in it.

• Indicator species = plants or animals that show something about the environment by their presence, absence, abundance or scarcity.– They are early warning signs because they are the

most sensitive to change or they are very tolerant of chemicals or low levels of oxygen.

• Why are these indirect methods?

Using the method

• How could you use this method to determine if an area of a river is polluted?– Kick nets for Biotic Index– Water Sample for BOD

• BOD and Biotic Indices are usually used together: – What does the Biotic Index show that BOD

does not?

Collecting Organisms

Other Abiotic Factors to Measure in Water

– Turbidity– Flow Velocity– pH– Temperature

Turbidity• Turbidity is the cloudiness or haziness of

a fluid caused by individual particles, that are generally invisible to the naked eye– The measurement of turbidity is a key test of

water quality– How can Turbidity affect the health of an

aquatic ecosystem?

Monitoring Turbidity

Using a Secchi Disk to measure the depth of water where photosynthesis

can still occur

LaMotte Turbidity WaterChemical Test Kit

Turbidity Columns

1 is the control with distilled water and the other has the

sample water

Flow Velocity• The speed of water

movement– Normally studied in

streams or rivers– Time how long it

takes for objects to pass between two poles 5 meters apart at different depths and take an average.

– How might this affect the health of an aquatic ecosystem?