Water Pollution:
Contaminants and Testing Procedures
S
What is Water Pollution?
S Water pollution - any
change in water quality
that harms humans or
other living organisms or
makes water unsuitable
for desired uses.
Application: “The Mistake by the River”
Cuyahoga River in the
Fall ©Tom Jones
http://csudigitalhumanities.org/ex
hibits/items/show/1328
A Burning River?
The Plain Dealer File
http://oceanservice.noaa.gov/education/
kits/pollution/02history.html
http://www.youtube.com/watch?v=tZA9OX2joUc&feature=r
elated
What are the sources of water pollution?
S Point Sources
S Can be traced back to one
particular origin
S
S
Industrial Plants (Power,
Chemical, Waste Treatment)
Drain pipes, Sewer Lines,
Underground Mines
S Nonpoint Sources
S Tend to be widespread with
many regions contributing to
the water pollution.
S
S
Agricultural Runoff
Stormwater Runoff (Roads
and Parking Lots)
Fig. 11-23, p. 260
Types of Contaminants
S Pathogens – Wastes from Humans and Animals
S Plant Nutrients – Nitrates & Phosphates
S Organics – Oil, Gasoline, Plastics, & Pesticides
S Inorganics – Salt, Metal Compounds
S Sediment – Total Suspended Solids
S Heavy Metals
S Thermal
Most Commonly Tested Parameters
S Temperature
S pH
S Nitrates
S Phosphates
S Dissolved Oxygen
S Turbidity
S Specific Conductivity
S Total Dissolved Solids
S Total Suspended Solids
Water Quality Index
Water Quality Index (WQI) is a measure of how polluted a body of water
actually is.
It can take many different parameters into consideration.
(6 parameters are typically used to calculate WQI)
Utilizes a weighting factor to differentiate between important parameters and
less-important parameters.
Q-Values are numbers that are given in a table and correlate to the level of
each parameter to characterize each on a scale of 0-100 (100 being best)
Water Quality Index
Q-Value
Weight Factor
0.17
Dissolved Oxygen
Test Result
103.1% Sat.
Fecal Coliform
2 / 100mL
0.16
pH
7.59
0.11
BOD (5-day)
1.75 mg/l
0.11
Temperature
1°C
0.10
Phosphates
.45 mg/l
0.10
Nitrates
.6 mg/l
0.10
Turbidity
50 cm
0.08
Total WQI
Subtotal
Water Quality Index
Test Results
Q-Value
Q-Value
X Weighting
Factor
Add all
Subtotals
Water Quality Index
Parameter
Tested
Value
Dissolved
Oxygen
90
0.3
Nitrate
1.75
0.2
Phosphate
0.3
0.2
pH
6.70
0.3
Totals
Q-Value
Weighting Calculation
Factor
Water Quality Index
Dissolved Oxygen: % saturation = 90
1. In the DO column find the value equal to
90.
2. Write down the Q-Value to the right of that
number (Q-value = 95).
Water Quality Index
Parameter
Tested
Value
Q-Value
Weighting
Factor
Calculation
Dissolved
Oxygen
90
95
0.3
95 X 0.3 = 28.5
Nitrate
1.75
0.2
Phosphate
0.3
0.2
pH
6.70
0.3
Totals
Water Quality Index
Nitrate: 1.75 mg/L
1. In the Nitrate-N Column find the values
closest to 1.75. This number falls between 1.5
and 2 in this column
2. Since there is no value matching exactly to
1.75, estimate the Q-value between 92 and 90
(Q-value = 91).
Water Quality Index
Parameter
Tested
Value
Q-Value
Weighting
Factor
Calculation
Dissolved
Oxygen
90
95
0.3
28.5
Nitrate
1.75
91
0.2
91 X 0.2 = 18.2
Phosphate
0.3
0.2
pH
6.70
0.3
Totals
Water Quality Index
Phosphate: 0.3 mg/L
Water Quality Index
Phosphate: 0.3 mg/L
1. In the Total Phosphate column find the value
equal to 0.3 (similar to the dissolved oxygen).
2. Write down the Q-Value to the right of that
number (Q-value = 90).
Water Quality Index
Parameter
Tested
Value
Q-Value
Weighting
Factor
Calculation
Dissolved
Oxygen
90
95
0.3
28.5
Nitrate
1.75
91
0.2
18.2
Phosphate
0.3
90
0.2
90 X 0.2 = 18.0
pH
6.70
Totals
0.3
Water Quality Index
pH: 6.70
1. In the pH column find the values closest to
6.70. This number falls between 6 and 7.
2. Since there is no value matching exactly to
6.70, estimate the Q-value between 55 and 90
(Q-value = 81).
Water Quality Index
pH
6
Q-value 55
7
90
Water Quality Index
pH
6
Q-value 55
6.5
7
72.5
90
(55+90) / 2 = 72.5
Water Quality Index
pH
6
Q-value 55
6.5
6.75
7
72.5
81.25
90
(72.5+90) / 2 = 81.25
Water Quality Index
Parameter
Tested
Value
Q-Value
Weighting
Factor
Calculation
Dissolved
Oxygen
90
95
0.3
28.5
Nitrate
1.75
91
0.2
18.2
Phosphate
0.3
90
0.2
18.0
pH
6.70
81
0.3
81 X 0.3 = 24.3
Totals
Water Quality Index
Parameter
Tested
Value
Q-Value
Weighting
Factor
Calculation
Dissolved
Oxygen
90
95
0.3
28.5
Nitrate
1.75
91
0.2
18.2
Phosphate
0.3
90
0.2
18.0
pH
6.70
81
0.3
24.3
Totals
28.5 + 18.2 +
18.0 + 24.3
= 89.0
Water Quality Index
Water Quality Percentages
Excellent
90-100%
Good
70-90%
Medium
50-70%
Bad
25-50%
Very Bad
0-25%