Turbidity refers to the cloudiness of water caused by suspended solids. It can be increased by erosion, urban and agricultural runoff, sediment mixing from water bottoms, and algal overgrowth from farm runoff. pH measures acidity in water and can change due to acid rain, stormwater, and agricultural runoff. Dissolved oxygen in water is important for fish and comes from water movement and photosynthesis but can decrease due to thermal pollution and eutrophication. The biotic index uses the types of organisms in water to measure quality, with more species indicating better quality. Biological oxygen demand measures how much oxygen bacteria need to break down organic pollutants in water.

1. THINGS WE
NEED TO
KNOW
ABOUT
WATER
TURBIDITY
AND WATER
POLLUTION
Kella Randolph B.S.,
M.Ed.
https://www.biologycorner.com/resources/pond3
.jpg

2. VOCABULARY
• Biotic Index/ A way to measure the quality of a body if water based on the types of
organisms that live there
• Turbidity/ The amount of sediment that is suspended in a body of water
• pH/ The measure of acidity in a body of water (pH<7 = acid and pH>7 = base)
• Point Source Pollution/ A source of pollution that is can be identified from a specific
source, such as a smokestack at a factory
• Nonpoint Source Pollution/ A source of pollution that cannot be directly identified as being
from a specific source, such as stormwater runoff
• Stormwater Runoff/ Rain-water that falls onto surfaces such as roads, sidewalks, roofs,
etc., picks up contaminants on these surfaces and carries them to bodies of water

3. T U R B I D I T Y I S T H E
M E A S U R E O F S O L I D S
S U S P E N D E D I N A B O D Y
O F WAT E R .
Four things that can increase
turbidity.
1. runoff from erosion,
https://upload.wikimedia.org/wikipedia/commons/9/9a/Runoff_from_Excelsio
r_Geyser_to_Firehole_River_at_Midway_Geyser_Basin.jpg
2. urban runoff,
https://upload.wikimedia.org/wikipedia/commons/d/d2/Construction_runoff_
Davidson_(6124078615).jpg
3. sediment mixing from the bottom of
the water,
https://s3-us-west-2.amazonaws.com/courses-images/wp-
content/uploads/sites/1462/2017/01/30182728/transportation-of-
sediments.png
4. algal overgrowth from agricultural
runoff.
(https://publiclab.org/system/images/photos/000/022/854/large/dam-
with-algae-growth.jpg)
41.
2
.
3
.

5. PH IS A MEASURE OF HOW
ACIDIC/BASIC WATER IS.
• pH is the measure of acidity of the water.
• Surface freshwater’s pH is 6.5 - 8.
• When acid rain falls into the fresh water, it will cause the pH to
become lower.
• Stormwater runoff as well as runoff from agriculture can also
change the pH in bodies of water.
• The pH scale ranges from 0 to 14, with 7 being neutral. pHs less
than 7 are acidic while pHs greater than 7 are alkaline (basic).
• Credit: robin_ph / stock.adobe.com
https://www.usgs.gov/media/images/ph-scale-0

6. Fast movement increases
oxygen in water
Fish absorb oxygen dissolved in the water and use
it for cellular respiration.
Dissolved oxygen enters the water through movement and
via photosynthesis of the water plants.
Fast moving water has an increased dissolved oxygen
content, while slow moving water has a lower
dissolved oxygen content.
Thermal pollution occurs when high temperature water
is dumped into bodies of water.
Eutrophication is a process that can also lead
to a reduction in dissolved oxygen.
Top photo:
https://get.pxhere.com/photo/aqua-beverage-blue-bubbles-clear-close-up-cold-drink-dehydrated-dehydration-drink-drinkable-
drinking-drinking-water-fluid-fresh-freshness-glass-h2o-health-healthy-hydration-hygiene-liquid-macro-medical-care-mineral-water-
motion-pouring-purified-purity-refreshment-rehydration-splash-thirsty-transparent-water-wellbeing-wellness-1568951.jpg
https://www.publicdomainpictures.net/pictures/30000/nahled/fast-
flowing-river.jpg

7. HOW FISH
“BREATHE”
• You can see fish’s gills when you look at
their faces. They are lines on the sides of a
fish’s face. The gills are also inside the
fishes’ body, but those can’t be seen from
the outside– just like our own lungs.
• First, the water goes into the fishes’
mouth and through the gills. As the water
leaves the gills it returns to the ocean.
Additionally, the carbon dioxide the fish
creates is also removed as the water
leaves the gills.
• The gills are a like a filter, and they
collect all the oxygen the fish need to
breath. After the gills pick up the oxygen, it
is sent throughout their blood and fuels
their bodies.
• Text from:
https://askdruniverse.wsu.edu/2018/01/07/how-do-fish-
breathe/
https://upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Tuna_Gills_in_
Situ_01.jpg/190px-Tuna_Gills_in_Situ_01.jpg
https://thealevelbiologist.co.uk/images/gills-an-o2.jpg
https://i.stack.imgur.com/4KO2o.jpg

8. UNDERWATER
PLANTS NEED
SUNLIGHT TOO
Too much turbidity can
cause organisms to die
because sunlight
cannot enter the water
https://farm5.staticflickr.com/4114/4850211841_88bed0bc92_z.jpg https://c2.staticflickr.com/4/3745/12801115735_a6fb3177f6_b.jpg

9. MODERN FERTILIZERS
CAUSE WATER
POLLUTION
• Nitrates can be found in fertilizers & the waste
materials from livestock and are used as fertilizers for
crops.
• Nitrates are used by farmers which, in turn, can
overgrow a body of water causing eutrophication.
•
• Eutrophication will lead to the death of fish.
•
• Phosphates are found in fertilizers and detergents.
•
• Phosphates can also cause an overgrowth of algae.
https://upload.wikimedia.org/wikipedia/commons/b/ba/Pesticides_application_01.jpg
http://www.scielo.br/img/revistas/sa/v63n2/28839f4.gif

10. POINT-
SOURCE AND
NON-POINT-
SOURCE
POLLUTION
• https://dr282zn36sxxg.cloudfront.net/datastreams/f-
d%3Ac8b661186fb43f1573f40f6d2d8cf858049bb6323fd62b0020bc3d57%2BIMAGE_TINY%2BIMAGE_
TINY.1

11. THE BIOTIC INDEX
• The biotic index is used to determine water quality.
• The different species of organisms living in a body of water are
used to assess water quality.
•
• Healthy bodies of water will have a high biotic index.
https://www.mrgscience.com/uploads/2/0/7/9/20796234/3365809_or
ig.jpg
https://www.mrgscience.com/uploads/2/0/7/9/20796234/5373948_ori
g.jpeg

12. Biological Oxygen Demand (BOD)
and Water
Biological oxygen demand (BOD) generally
represents how much oxygen is needed to
break down organic matter in water.
Biochemical oxygen demand (BOD)
represents the amount of oxygen consumed
by bacteria and other microorganisms while
they decompose organic matter under aerobic
(oxygen is present) conditions at a specified
temperature.
When you look at water in a lake the one thing
you don't see is oxygen. In a way, we think
that water is the opposite of air, but the
common lake or stream does contain small
amounts of oxygen, in the form of dissolved
oxygen. Although the amount of dissolved
oxygen is small, up to about ten molecules of
oxygen per million of water, it is a crucial
component of natural water bodies; the
presence of a sufficient concentration of
dissolved oxygen is critical to maintaining the
aquatic life and aesthetic quality of streams
and lakes.
https://www.goodfreephotos.com/albums/croatia/plitvice-lakes-national-
park/beautiful-lakes-and-water-at-plitvice-lakes-national-park-croatia.jpg

13. • Determining how organic matter affects
the concentration of dissolved oxygen in
a stream or lake is integral to water-
quality management. BOD is a measure
of the amount of oxygen required to
remove waste organic matter from water
in the process of decomposition by
aerobic bacteria (those bacteria that live
only in an environment containing
oxygen). The waste organic matter is
stabilized or made unobjectionable
through its decomposition by living
bacterial organisms which need oxygen
to do their work. BOD is used, often in
wastewater-treatment plants, as an
index of the degree of organic pollution
in water.
http://www.mrgscience.com/uploads/2/0/7/9/20796234/6501875.jpg?
492

14. AIR IS PUT
INTO THE
WASTEWATER
• By adding air to the
wastewater, the bacteria
that eat the organic
material can digest it and
thrive.
• In a process that comes
later, the bacteria are
exposed to Ultraviolet
(UV) light which kills
them.
https://upload.wikimedia.org/wikipedia/commons/
thumb/f/f4/Aerated_pool_for_waste_water_treatm
ent.JPG/1280px-
Aerated_pool_for_waste_water_treatment.JPG
https://upload.wikimedia.org/wikipedia/commons/
thumb/7/75/Marlborough_East_Wastewater_Treat
ment_Plant_Aerial.JPG/1200px-
Marlborough_East_Wastewater_Treatment_Plant
_Aerial.JPG