water quality index

What is the trend?
#1) For the ecosystem shown below, calculate the % of energy in
Kilocalories transferred from one level to the next.
# of Kilocalories Available % of Kilocalories Reta ined
Primary Consumers
Secondary Consumers 383
Tertiary Consumers
1970 Clean Air & Water Act
• 1970 National Sanitation Foundation
devised a standard scale to rate or “grade”
the quality of water
• The WQI is based on nine different biotic
and abiotic factors
• We will test six of these factors in our
investigation: temperature, dissolved
oxygen, pH, total dissolved solids, benthic
macroinvertebrate diversity and fecal
coliform levels
Physiology of Mammalian Diving Reflex
• In response to need
to conserve oxygen,
cold water causes
reduction in heartbeat
constriction of
bloodflow and a shift
of blood to the
thoracic cavity
• True only of
Why is this response necessary
in homeotherms?
Biological Oxygen Demand
• Fish, invertebrates,
plants, and aerobic
bacteria all require
oxygen for
• The amount of
oxygen required by
an ecosystem is its
Biological Oxygen
Demand (B.O.D.)
Dissolved Oxygen (D.O.)
• Amount of oxygen
gas dissolved in
1million molecules of
• Can range from
0-18ppm normally
• 5-6ppm needed to
sustain most complex
aquatic life
Sources of Dissolved Oxygen
• Much of the dissolved oxygen in water comes from
the atmosphere. After dissolving at the surface,
oxygen is distributed by current and turbulence.
• Algae and rooted aquatic plants also deliver oxygen
to water through photosynthesis.
How Do Organisms Stay
Underwater All Winter?
Temperature v. Dissolved
• Purpose: To determine the nature of the
relationship (if any) between dissolved
oxygen concentration and temperature.
• Hypothesis: What do you think the
relationship is between these variables?
Direct, indirect, optimal or no relationship?
What is your reasoning for this?
Getting Started
• 1) Plug in the Dissolved
oxygen probe to Channel 1
of the LabQuest
• 2) Plug in the Stainless
Steel Temperature Probe to
Channel 2 of the LabQuest
• 3) Power up LabQuest
• 4) Set up sensors for
channels 1 & 2 from sensors
• 5) D.O. probe must be
“warmed up” for 10 minutes
before data collection
Applying The Variable
• Fill one 250 mL beaker with ice
& water
• Fill one 250 mL beaker with
40-50 water (use hotplate &
• Place 100 mL of ice water in
milk jug & shake for 2 minutes
• Pour “aerated water” from jug
into paper cup and place both
temp & D.O. probe into cup.
Let the values stabilize for
about 1 minute
• Record the temp & D.O. of the
water in the cup in data table
• Pour 75 mL of the ice
water from the cup back
into the milk jug
• Add 25 mL of the 40-50
°C water to the milk jug
• Re-aerate/shake for 2
minutes and repeat
temp/D.O. sampling
• Repeat previous
sampling steps until water
temp in paper cup is
appx. 35 °C.
Why Did The Catfish Survive?
1) Temperature
• High temperatures may
indicate thermal
pollution and place
organisms at risk
• Temperatures may also
increase the rate of
metabolism, raising the
biological oxygen
demand (B.O.D.)
• Temperatures
negatively impact the
amount of dissolved
The change in temperature with
depth is called a THERMOCLINE
• Measures the amount
of oxygen dissolved in
• Important for aquatic
organisms regarding
cellular respiration
• Can also indirectly
measure the amount
of autotrophs in an
aquatic ecosystem
• Measurement of acidity or alkalinity in the
water source
• Extremely acidic or basic pH may indicate
industrial runoff (i.e. soaps, batteries, etc.)
• Moderately acidic pH may indicate higher
rates of decomposition (due to CO2
Different aquatic organisms have
different ranges of pH tolerance
4) Total Dissolved Solids (TDS)
• Measurement of how much organic
and inorganic matter is being carried
in the water
• High TDS values indicate high
amounts of erosion upstream
• Dissolved solids may also block
sunlight and/or their decomposition
may reduce the dissolved oxygen of
the water source
Q Values
• Each biotic or abiotic measurement should
be compared with its unweighted Q value
• The Q value is the “grade” for that
aspect of the water quality
• For dissolved oxygen, the Q value is
obtained by dividing the measured D.O.
(from the probe) by the saturated O2 level
This % is used to find Q
• Each of the four Q values is multiplied by its
relative weight to determine the abiotic WQI
D.O. Q Score x 0.38
pH Q Score x 0.24
Temp. Q Score x 0.22
TDS Q Score x 0.16
Sum of Weighted Q Scores = WQI
Biotic Measures of Water Quality
Fecal Coliform
Fecal v. General Coliform
• General Coliform =
bacteria that has
come in contact with
plant or animal life
• Fecal Coliform =
Bacteria from the
digestive tract of
mammals or birds
Benthic Macroinvertebrates
• Bottom-dwelling,
spineless animals
• Some species are
very pollution tolerant
while others are not
• Depending upon the
diversity of
one may indirectly
assess the river’s
health re: nitrogen
and phosphorus