Water Quality Indicators Notes
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Transcript Water Quality Indicators Notes
What is an Indicator?
Water is seen as “good quality” or “bad quality” based
off of several criteria
These criteria indicate the health of the water
Includes turbidity, pH, dissolved oxygen, temperature,
nitrates, and bio-indicators
Definition: Turbidity
Turbidity: measure of the degree to which water looses
its transparency due to the presence of suspended
particulates
This is a river with high turbidity
Levels: Turbidity
Ideal level: 1 NTU (Nephelometric unit)
High level: 5 NTU
Causes: Turbidity
Causes of increased turbidity:
Increased levels of phytoplankton sediment from
erosion, re-suspended sediments from the bottom
(stirred by bottom dwellers), waste discharge, algae
growth, and urban runoff
Results: Turbidity
Results of high turbidity:
High turbidity increases the
absorption of sunlight thus
making the water warmer.
Warmer water has lower levels of
dissolved oxygen causing fish
and larvae to die
Definition: pH
pH: the acidity of the water (presence of hydrogen ion)
07 is acidic
7 is neutral
7 14 is basic
Levels: pH
Surface Freshwater: 6.0 9.0
Swamps: as low as 4.3
Salt Water: 8.1 but as low as 7.7
Causes: pH
Causes of changes of pH:
Natural conditions (especially
in swamps), dumping of waste
(batteries) and farm runoff
(lime)
Results: pH
Results of changes of pH:
A change in pH by 2 units results in a water system
having 100 times a difference in acidity
Most aquatic life cannot withstand water outside the
optimum pH thus resulting in death
Definition: Dissolved Oxygen
Dissolved Oxygen: the oxygen dissolved in the water
Levels: Dissolved Oxygen
Average level: 9.0 ppm (parts per million)
Must be 4-5 ppm to support diverse population of fish
Causes: Dissolved Oxygen
Causes of changes in dissolved oxygen: turbulent
actions (waves, rapids), water depth, and plant growth
Results: Dissolved Oxygen
Results of changes in dissolved oxygen:
When DO drops too low, fish die
When DO is high, the water actually tastes better but
can corrode water pipes
Definition: Temperature
Temperature: the measure of average kinetic energy
Levels: Temperature
Low: cannot be tolerated below 32 degrees F
High: only rough fish can tolerate temperatures above
97 degrees F
Causes: Temperature
Causes of change in temperature: source of water, time
of year, suspended sediment, depth of water, and
shade from shoreline vegetation
Results: Temperature
Results of changes in temperature: changes in
temperature can make aquatic life susceptible to
disease and at extreme levels can result in death
Definition: Nitrates
Nitrates: compound that contains the nitrogen based
polyatomic ion NO3 (Ex: Sodium Nitrate)
Levels: Nitrates
Drinking Water Max: 10 mg/L
Fish: Below 90 mg/L seems to have no effect on warm
water fish
Causes: Nitrates
Causes of nitrates:
Fertilizer runoff (both farm and
home), manure pits, leaks in
septic systems, animal waste, and
rain trapping car exhaust
Results: Nitrates
Results of presence of nitrates:
Nitrates can increase the plant production and fish
population resulting in overcrowding
If algae increases due to nitrates, the pH levels
decrease killing fish
Nitrates are converted to nitrites in humans (can kill
children)
Definition: Bio-indicators
Bio-indicators: macroinvertibrates found living in
water (they tend to remain in one place) that are
sensitive to pollution
Levels: Bio-indicators
High level of variety: healthy water source
Small level of variety: poor water source (indicator of
high levels of pollution)
Causes: Bio-indicators
Causes of changes in bio-
indicators:
Pollution that results in
changes in pH,
temperature, dissolved
oxygen, or nitrate levels
Results: Bio-indicators
Results of few varieties of bio-indicators present: the
lack of a large number of different varieties of bioindicators is indicative of pollution
Foldable - INSTRUCTIONS
Title Page – Use title given on Table of Contents. Add Name, Date, Block Color
in upper right hand corner. Page number goes on the bottom outermost corner
of the foldable. Title: Water Quality Indicators Foldable Page # 48
Each Tab Should have the following:
Title of Indicator:
1. What is an indicator?
2. Turbidity
3. pH
4. Dissolved Oxygen
5. Temperature
6. Nitrates
7. Bio-Indicators
Definition & Levels
Causes
Results
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